Version abc71001

96 files changed, 30876 insertions, 0 deletions

diff --git a/src/opt/cut/abcCut.c b/src/opt/cut/abcCut.c
new file mode 100644
index 00000000..9bbd5790
--- /dev/null
+++ b/src/opt/cut/abcCut.c
@@ -0,0 +1,492 @@
+/**CFile****************************************************************
+
+  FileName    [abcCut.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Interface to cut computation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: abcCut.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "cut.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Abc_NtkPrintCuts( void * p, Abc_Ntk_t * pNtk, int fSeq );
+static void Abc_NtkPrintCuts_( void * p, Abc_Ntk_t * pNtk, int fSeq );
+
+
+extern int nTotal, nGood, nEqual;
+
+// temporary
+//Vec_Int_t * Abc_NtkGetNodeAttributes( Abc_Ntk_t * pNtk ) { return NULL; }
+Vec_Int_t * Abc_NtkGetNodeAttributes( Abc_Ntk_t * pNtk ) 
+{
+    Vec_Int_t * vAttrs = Vec_IntStart( Abc_NtkObjNumMax(pNtk) + 1 );
+    int i;
+    Abc_Obj_t * pObj;
+
+//    Abc_NtkForEachCi( pNtk, pObj, i )
+//        Vec_IntWriteEntry( vAttrs, pObj->Id, 1 );
+
+    Abc_NtkForEachObj( pNtk, pObj, i )
+    {
+//        if ( Abc_ObjIsNode(pObj) && (rand() % 4 == 0) )
+        if ( Abc_ObjIsNode(pObj) && Abc_ObjFanoutNum(pObj) > 1 && !Abc_NodeIsMuxControlType(pObj) && (rand() % 3 == 0) )
+            Vec_IntWriteEntry( vAttrs, pObj->Id, 1 );
+    }
+    return vAttrs; 
+}
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Man_t * Abc_NtkCuts( Abc_Ntk_t * pNtk, Cut_Params_t * pParams )
+{
+    ProgressBar * pProgress;
+    Cut_Man_t *  p;
+    Abc_Obj_t * pObj, * pNode;
+    Vec_Ptr_t * vNodes;
+    Vec_Int_t * vChoices;
+    int i;
+    int clk = clock();
+
+    extern void Abc_NtkBalanceAttach( Abc_Ntk_t * pNtk );
+    extern void Abc_NtkBalanceDetach( Abc_Ntk_t * pNtk );
+
+    nTotal = nGood = nEqual = 0;
+
+    assert( Abc_NtkIsStrash(pNtk) );
+    // start the manager
+    pParams->nIdsMax = Abc_NtkObjNumMax( pNtk );
+    p = Cut_ManStart( pParams );
+    // compute node attributes if local or global cuts are requested
+    if ( pParams->fGlobal || pParams->fLocal )
+    {
+        extern Vec_Int_t * Abc_NtkGetNodeAttributes( Abc_Ntk_t * pNtk );
+        Cut_ManSetNodeAttrs( p, Abc_NtkGetNodeAttributes(pNtk) );
+    }
+    // prepare for cut dropping
+    if ( pParams->fDrop )
+        Cut_ManSetFanoutCounts( p, Abc_NtkFanoutCounts(pNtk) );
+    // set cuts for PIs
+    Abc_NtkForEachCi( pNtk, pObj, i )
+        if ( Abc_ObjFanoutNum(pObj) > 0 )
+            Cut_NodeSetTriv( p, pObj->Id );
+    // compute cuts for internal nodes
+    vNodes = Abc_AigDfs( pNtk, 0, 1 ); // collects POs
+    vChoices = Vec_IntAlloc( 100 );
+    pProgress = Extra_ProgressBarStart( stdout, Vec_PtrSize(vNodes) );
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+    {
+        // when we reached a CO, it is time to deallocate the cuts
+        if ( Abc_ObjIsCo(pObj) )
+        {
+            if ( pParams->fDrop )
+                Cut_NodeTryDroppingCuts( p, Abc_ObjFaninId0(pObj) );
+            continue;
+        }
+        // skip constant node, it has no cuts
+//        if ( Abc_NodeIsConst(pObj) )
+//            continue;
+        Extra_ProgressBarUpdate( pProgress, i, NULL );
+        // compute the cuts to the internal node
+        Abc_NodeGetCuts( p, pObj, pParams->fDag, pParams->fTree );  
+        // consider dropping the fanins cuts
+        if ( pParams->fDrop )
+        {
+            Cut_NodeTryDroppingCuts( p, Abc_ObjFaninId0(pObj) );
+            Cut_NodeTryDroppingCuts( p, Abc_ObjFaninId1(pObj) );
+        }
+        // add cuts due to choices
+        if ( Abc_AigNodeIsChoice(pObj) )
+        {
+            Vec_IntClear( vChoices );
+            for ( pNode = pObj; pNode; pNode = pNode->pData )
+                Vec_IntPush( vChoices, pNode->Id );
+            Cut_NodeUnionCuts( p, vChoices );
+        }
+    }
+    Extra_ProgressBarStop( pProgress );
+    Vec_PtrFree( vNodes );
+    Vec_IntFree( vChoices );
+PRT( "Total", clock() - clk );
+//Abc_NtkPrintCuts( p, pNtk, 0 );
+//    Cut_ManPrintStatsToFile( p, pNtk->pSpec, clock() - clk );
+
+    // temporary printout of stats
+    if ( nTotal )
+    printf( "Total cuts = %d. Good cuts = %d.  Ratio = %5.2f\n", nTotal, nGood, ((double)nGood)/nTotal );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Cut computation using the oracle.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkCutsOracle( Abc_Ntk_t * pNtk, Cut_Oracle_t * p )
+{
+    Abc_Obj_t * pObj;
+    Vec_Ptr_t * vNodes;
+    int i, clk = clock();
+    int fDrop = Cut_OracleReadDrop(p);
+
+    assert( Abc_NtkIsStrash(pNtk) );
+
+    // prepare cut droppping
+    if ( fDrop )
+        Cut_OracleSetFanoutCounts( p, Abc_NtkFanoutCounts(pNtk) );
+
+    // set cuts for PIs
+    Abc_NtkForEachCi( pNtk, pObj, i )
+        if ( Abc_ObjFanoutNum(pObj) > 0 )
+            Cut_OracleNodeSetTriv( p, pObj->Id );
+
+    // compute cuts for internal nodes
+    vNodes = Abc_AigDfs( pNtk, 0, 1 ); // collects POs
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+    {
+        // when we reached a CO, it is time to deallocate the cuts
+        if ( Abc_ObjIsCo(pObj) )
+        {
+            if ( fDrop )
+                Cut_OracleTryDroppingCuts( p, Abc_ObjFaninId0(pObj) );
+            continue;
+        }
+        // skip constant node, it has no cuts
+//        if ( Abc_NodeIsConst(pObj) )
+//            continue;
+        // compute the cuts to the internal node
+        Cut_OracleComputeCuts( p, pObj->Id, Abc_ObjFaninId0(pObj), Abc_ObjFaninId1(pObj),  
+                Abc_ObjFaninC0(pObj), Abc_ObjFaninC1(pObj) );
+        // consider dropping the fanins cuts
+        if ( fDrop )
+        {
+            Cut_OracleTryDroppingCuts( p, Abc_ObjFaninId0(pObj) );
+            Cut_OracleTryDroppingCuts( p, Abc_ObjFaninId1(pObj) );
+        }
+    }
+    Vec_PtrFree( vNodes );
+//PRT( "Total", clock() - clk );
+//Abc_NtkPrintCuts_( p, pNtk, 0 );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Man_t * Abc_NtkSeqCuts( Abc_Ntk_t * pNtk, Cut_Params_t * pParams )
+{
+/*
+    Cut_Man_t *  p;
+    Abc_Obj_t * pObj, * pNode;
+    int i, nIters, fStatus;
+    Vec_Int_t * vChoices;
+    int clk = clock();
+
+    assert( Abc_NtkIsSeq(pNtk) );
+    assert( pParams->fSeq );
+//    assert( Abc_NtkIsDfsOrdered(pNtk) );
+
+    // start the manager
+    pParams->nIdsMax = Abc_NtkObjNumMax( pNtk );
+    pParams->nCutSet = Abc_NtkCutSetNodeNum( pNtk );
+    p = Cut_ManStart( pParams );
+
+    // set cuts for the constant node and the PIs
+    pObj = Abc_AigConst1(pNtk);
+    if ( Abc_ObjFanoutNum(pObj) > 0 )
+        Cut_NodeSetTriv( p, pObj->Id );
+    Abc_NtkForEachPi( pNtk, pObj, i )
+    {
+//printf( "Setting trivial cut %d.\n", pObj->Id );
+        Cut_NodeSetTriv( p, pObj->Id );
+    }
+    // label the cutset nodes and set their number in the array
+    // assign the elementary cuts to the cutset nodes
+    Abc_SeqForEachCutsetNode( pNtk, pObj, i )
+    {
+        assert( pObj->fMarkC == 0 );
+        pObj->fMarkC = 1;
+        pObj->pCopy = (Abc_Obj_t *)i;
+        Cut_NodeSetTriv( p, pObj->Id );
+//printf( "Setting trivial cut %d.\n", pObj->Id );
+    }
+
+    // process the nodes
+    vChoices = Vec_IntAlloc( 100 );
+    for ( nIters = 0; nIters < 10; nIters++ )
+    {
+//printf( "ITERATION %d:\n", nIters );
+        // compute the cuts for the internal nodes
+        Abc_AigForEachAnd( pNtk, pObj, i )
+        {
+            Abc_NodeGetCutsSeq( p, pObj, nIters==0 );
+            // add cuts due to choices
+            if ( Abc_AigNodeIsChoice(pObj) )
+            {
+                Vec_IntClear( vChoices );
+                for ( pNode = pObj; pNode; pNode = pNode->pData )
+                    Vec_IntPush( vChoices, pNode->Id );
+                Cut_NodeUnionCutsSeq( p, vChoices, (pObj->fMarkC ? (int)pObj->pCopy : -1), nIters==0 );
+            }
+        }
+        // merge the new cuts with the old cuts
+        Abc_NtkForEachPi( pNtk, pObj, i )
+            Cut_NodeNewMergeWithOld( p, pObj->Id );
+        Abc_AigForEachAnd( pNtk, pObj, i )
+            Cut_NodeNewMergeWithOld( p, pObj->Id );
+        // for the cutset, transfer temp cuts to new cuts
+        fStatus = 0;
+        Abc_SeqForEachCutsetNode( pNtk, pObj, i )
+            fStatus |= Cut_NodeTempTransferToNew( p, pObj->Id, i );
+        if ( fStatus == 0 )
+            break;
+    }
+    Vec_IntFree( vChoices );
+
+    // if the status is not finished, transfer new to old for the cutset
+    Abc_SeqForEachCutsetNode( pNtk, pObj, i )
+        Cut_NodeNewMergeWithOld( p, pObj->Id );
+
+    // transfer the old cuts to the new positions
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        Cut_NodeOldTransferToNew( p, pObj->Id );
+
+    // unlabel the cutset nodes
+    Abc_SeqForEachCutsetNode( pNtk, pObj, i )
+        pObj->fMarkC = 0;
+if ( pParams->fVerbose )
+{
+PRT( "Total", clock() - clk );
+printf( "Converged after %d iterations.\n", nIters );
+}
+//Abc_NtkPrintCuts( p, pNtk, 1 );
+    return p;
+*/
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void * Abc_NodeGetCutsRecursive( void * p, Abc_Obj_t * pObj, int fDag, int fTree )
+{
+    void * pList;
+    if ( pList = Abc_NodeReadCuts( p, pObj ) )
+        return pList;
+    Abc_NodeGetCutsRecursive( p, Abc_ObjFanin0(pObj), fDag, fTree );
+    Abc_NodeGetCutsRecursive( p, Abc_ObjFanin1(pObj), fDag, fTree );
+    return Abc_NodeGetCuts( p, pObj, fDag, fTree );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void * Abc_NodeGetCuts( void * p, Abc_Obj_t * pObj, int fDag, int fTree )
+{
+    Abc_Obj_t * pFanin;
+    int fDagNode, fTriv, TreeCode = 0;
+//    assert( Abc_NtkIsStrash(pObj->pNtk) );
+    assert( Abc_ObjFaninNum(pObj) == 2 );
+
+
+    // check if the node is a DAG node
+    fDagNode = (Abc_ObjFanoutNum(pObj) > 1 && !Abc_NodeIsMuxControlType(pObj));
+    // increment the counter of DAG nodes
+    if ( fDagNode ) Cut_ManIncrementDagNodes( p );
+    // add the trivial cut if the node is a DAG node, or if we compute all cuts
+    fTriv = fDagNode || !fDag;
+    // check if fanins are DAG nodes
+    if ( fTree )
+    {
+        pFanin = Abc_ObjFanin0(pObj);
+        TreeCode |=  (Abc_ObjFanoutNum(pFanin) > 1 && !Abc_NodeIsMuxControlType(pFanin));
+        pFanin = Abc_ObjFanin1(pObj);
+        TreeCode |= ((Abc_ObjFanoutNum(pFanin) > 1 && !Abc_NodeIsMuxControlType(pFanin)) << 1);
+    }
+
+
+    // changes due to the global/local cut computation
+    {
+        Cut_Params_t * pParams = Cut_ManReadParams(p);
+        if ( pParams->fLocal )
+        {
+            Vec_Int_t * vNodeAttrs = Cut_ManReadNodeAttrs(p);
+            fDagNode = Vec_IntEntry( vNodeAttrs, pObj->Id );
+            if ( fDagNode ) Cut_ManIncrementDagNodes( p );
+//            fTriv = fDagNode || !pParams->fGlobal;
+            fTriv = !Vec_IntEntry( vNodeAttrs, pObj->Id );
+            TreeCode = 0;
+            pFanin = Abc_ObjFanin0(pObj);
+            TreeCode |=  Vec_IntEntry( vNodeAttrs, pFanin->Id );
+            pFanin = Abc_ObjFanin1(pObj);
+            TreeCode |= (Vec_IntEntry( vNodeAttrs, pFanin->Id ) << 1);
+        }
+    }
+    return Cut_NodeComputeCuts( p, pObj->Id, Abc_ObjFaninId0(pObj), Abc_ObjFaninId1(pObj),  
+        Abc_ObjFaninC0(pObj), Abc_ObjFaninC1(pObj), fTriv, TreeCode );  
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NodeGetCutsSeq( void * p, Abc_Obj_t * pObj, int fTriv )
+{
+    int CutSetNum;
+    assert( Abc_NtkIsSeq(pObj->pNtk) );
+    assert( Abc_ObjFaninNum(pObj) == 2 );
+    fTriv     = pObj->fMarkC ? 0 : fTriv;
+    CutSetNum = pObj->fMarkC ? (int)pObj->pCopy : -1;
+    Cut_NodeComputeCutsSeq( p, pObj->Id, Abc_ObjFaninId0(pObj), Abc_ObjFaninId1(pObj),  
+        Abc_ObjFaninC0(pObj), Abc_ObjFaninC1(pObj), Seq_ObjFaninL0(pObj), Seq_ObjFaninL1(pObj), fTriv, CutSetNum );  
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void * Abc_NodeReadCuts( void * p, Abc_Obj_t * pObj )
+{
+    return Cut_NodeReadCutsNew( p, pObj->Id );  
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NodeFreeCuts( void * p, Abc_Obj_t * pObj )
+{
+    Cut_NodeFreeCuts( p, pObj->Id );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkPrintCuts( void * p, Abc_Ntk_t * pNtk, int fSeq )
+{
+    Cut_Man_t * pMan = p;
+    Cut_Cut_t * pList;
+    Abc_Obj_t * pObj;
+    int i;
+    printf( "Cuts of the network:\n" );
+    Abc_NtkForEachObj( pNtk, pObj, i )
+    {
+        pList = Abc_NodeReadCuts( p, pObj );
+        printf( "Node %s:\n", Abc_ObjName(pObj) );
+        Cut_CutPrintList( pList, fSeq );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts for the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkPrintCuts_( void * p, Abc_Ntk_t * pNtk, int fSeq )
+{
+    Cut_Man_t * pMan = p;
+    Cut_Cut_t * pList;
+    Abc_Obj_t * pObj;
+    pObj = Abc_NtkObj( pNtk, 2 * Abc_NtkObjNum(pNtk) / 3 );
+    pList = Abc_NodeReadCuts( p, pObj );
+    printf( "Node %s:\n", Abc_ObjName(pObj) );
+    Cut_CutPrintList( pList, fSeq );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cut.h b/src/opt/cut/cut.h
new file mode 100644
index 00000000..dee05dfc
--- /dev/null
+++ b/src/opt/cut/cut.h
@@ -0,0 +1,165 @@
+/**CFile****************************************************************
+
+  FileName    [cut.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: .h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#ifndef __CUT_H__
+#define __CUT_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+#define CUT_SIZE_MIN    3      // the min K of the K-feasible cut computation
+#define CUT_SIZE_MAX   12      // the max K of the K-feasible cut computation
+
+#define CUT_SHIFT       8      // the number of bits for storing latch number in the cut leaves
+#define CUT_MASK        0xFF   // the mask to get the stored latch number
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Cut_ManStruct_t_         Cut_Man_t;
+typedef struct Cut_OracleStruct_t_      Cut_Oracle_t;
+typedef struct Cut_CutStruct_t_         Cut_Cut_t;
+typedef struct Cut_ParamsStruct_t_      Cut_Params_t;
+
+struct Cut_ParamsStruct_t_
+{
+    int                nVarsMax;          // the max cut size ("k" of the k-feasible cuts)
+    int                nKeepMax;          // the max number of cuts kept at a node
+    int                nIdsMax;           // the max number of IDs of cut objects
+    int                nBitShift;         // the number of bits used for the latch counter of an edge
+    int                nCutSet;           // the number of nodes in the cut set
+    int                fTruth;            // compute truth tables
+    int                fFilter;           // filter dominated cuts
+    int                fSeq;              // compute sequential cuts
+    int                fDrop;             // drop cuts on the fly
+    int                fDag;              // compute only DAG cuts
+    int                fTree;             // compute only tree cuts
+    int                fGlobal;           // compute only global cuts
+    int                fLocal;            // compute only local cuts
+    int                fRecord;           // record the cut computation flow
+    int                fFancy;            // perform fancy computations
+    int                fMap;              // computes delay of FPGA mapping with cuts
+    int                fVerbose;          // the verbosiness flag
+};
+
+struct Cut_CutStruct_t_
+{
+    unsigned           Num0       : 11;   // temporary number
+    unsigned           Num1       : 11;   // temporary number
+    unsigned           fSimul     :  1;   // the value of cut's output at 000.. pattern
+    unsigned           fCompl     :  1;   // the cut is complemented
+    unsigned           nVarsMax   :  4;   // the max number of vars [4-6]
+    unsigned           nLeaves    :  4;   // the number of leaves [4-6]
+    unsigned           uSign;             // the signature
+    unsigned           uCanon0;           // the canonical form 
+    unsigned           uCanon1;           // the canonical form 
+    Cut_Cut_t *        pNext;             // the next cut in the list
+    int                pLeaves[0];        // the array of leaves
+};
+
+static inline int        Cut_CutReadLeaveNum( Cut_Cut_t * p )  {  return p->nLeaves;   }
+static inline int *      Cut_CutReadLeaves( Cut_Cut_t * p )    {  return p->pLeaves;   }
+static inline unsigned * Cut_CutReadTruth( Cut_Cut_t * p )     {  return (unsigned *)(p->pLeaves + p->nVarsMax); }
+static inline void       Cut_CutWriteTruth( Cut_Cut_t * p, unsigned * puTruth )  { 
+    int i;
+    for ( i = (p->nVarsMax <= 5) ? 0 : ((1 << (p->nVarsMax - 5)) - 1); i >= 0; i-- )
+        p->pLeaves[p->nVarsMax + i] = (int)puTruth[i];
+}
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== cutApi.c ==========================================================*/
+extern Cut_Cut_t *      Cut_NodeReadCutsNew( Cut_Man_t * p, int Node );
+extern Cut_Cut_t *      Cut_NodeReadCutsOld( Cut_Man_t * p, int Node );
+extern Cut_Cut_t *      Cut_NodeReadCutsTemp( Cut_Man_t * p, int Node );
+extern void             Cut_NodeWriteCutsNew( Cut_Man_t * p, int Node, Cut_Cut_t * pList );
+extern void             Cut_NodeWriteCutsOld( Cut_Man_t * p, int Node, Cut_Cut_t * pList );
+extern void             Cut_NodeWriteCutsTemp( Cut_Man_t * p, int Node, Cut_Cut_t * pList );
+extern void             Cut_NodeSetTriv( Cut_Man_t * p, int Node );
+extern void             Cut_NodeTryDroppingCuts( Cut_Man_t * p, int Node );
+extern void             Cut_NodeFreeCuts( Cut_Man_t * p, int Node );
+/*=== cutCut.c ==========================================================*/
+extern void             Cut_CutPrint( Cut_Cut_t * pCut, int fSeq );
+extern void             Cut_CutPrintList( Cut_Cut_t * pList, int fSeq );
+extern int              Cut_CutCountList( Cut_Cut_t * pList );
+/*=== cutMan.c ==========================================================*/
+extern Cut_Man_t *      Cut_ManStart( Cut_Params_t * pParams );
+extern void             Cut_ManStop( Cut_Man_t * p );
+extern void             Cut_ManPrintStats( Cut_Man_t * p );
+extern void             Cut_ManPrintStatsToFile( Cut_Man_t * p, char * pFileName, int TimeTotal );
+extern void             Cut_ManSetFanoutCounts( Cut_Man_t * p, Vec_Int_t * vFanCounts );
+extern void             Cut_ManSetNodeAttrs( Cut_Man_t * p, Vec_Int_t * vFanCounts );
+extern int              Cut_ManReadVarsMax( Cut_Man_t * p );
+extern Cut_Params_t *   Cut_ManReadParams( Cut_Man_t * p );
+extern Vec_Int_t *      Cut_ManReadNodeAttrs( Cut_Man_t * p );
+extern void             Cut_ManIncrementDagNodes( Cut_Man_t * p );
+/*=== cutNode.c ==========================================================*/
+extern Cut_Cut_t *      Cut_NodeComputeCuts( Cut_Man_t * p, int Node, int Node0, int Node1, int fCompl0, int fCompl1, int fTriv, int TreeCode ); 
+extern Cut_Cut_t *      Cut_NodeUnionCuts( Cut_Man_t * p, Vec_Int_t * vNodes );
+extern Cut_Cut_t *      Cut_NodeUnionCutsSeq( Cut_Man_t * p, Vec_Int_t * vNodes, int CutSetNum, int fFirst );
+extern int              Cut_ManMappingArea_rec( Cut_Man_t * p, int Node );
+/*=== cutSeq.c ==========================================================*/
+extern void             Cut_NodeComputeCutsSeq( Cut_Man_t * p, int Node, int Node0, int Node1, int fCompl0, int fCompl1, int nLat0, int nLat1, int fTriv, int CutSetNum );
+extern void             Cut_NodeNewMergeWithOld( Cut_Man_t * p, int Node );
+extern int              Cut_NodeTempTransferToNew( Cut_Man_t * p, int Node, int CutSetNum );
+extern void             Cut_NodeOldTransferToNew( Cut_Man_t * p, int Node );
+/*=== cutOracle.c ==========================================================*/
+extern Cut_Oracle_t *   Cut_OracleStart( Cut_Man_t * pMan );
+extern void             Cut_OracleStop( Cut_Oracle_t * p );
+extern void             Cut_OracleSetFanoutCounts( Cut_Oracle_t * p, Vec_Int_t * vFanCounts );
+extern int              Cut_OracleReadDrop( Cut_Oracle_t * p );
+extern void             Cut_OracleNodeSetTriv( Cut_Oracle_t * p, int Node );
+extern Cut_Cut_t *      Cut_OracleComputeCuts( Cut_Oracle_t * p, int Node, int Node0, int Node1, int fCompl0, int fCompl1 );
+extern void             Cut_OracleTryDroppingCuts( Cut_Oracle_t * p, int Node );
+/*=== cutTruth.c ==========================================================*/
+extern void             Cut_TruthNCanonicize( Cut_Cut_t * pCut );
+/*=== cutPre22.c ==========================================================*/
+extern void             Cut_CellPrecompute();
+extern void             Cut_CellLoad();
+extern int              Cut_CellIsRunning();
+extern void             Cut_CellDumpToFile();
+extern int              Cut_CellTruthLookup( unsigned * pTruth, int nVars );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/cut/cutApi.c b/src/opt/cut/cutApi.c
new file mode 100644
index 00000000..980c6b12
--- /dev/null
+++ b/src/opt/cut/cutApi.c
@@ -0,0 +1,197 @@
+/**CFile****************************************************************
+
+  FileName    [cutNode.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Procedures to compute cuts for a node.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutNode.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the linked list of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_NodeReadCutsNew( Cut_Man_t * p, int Node )
+{
+    if ( Node >= p->vCutsNew->nSize )
+        return NULL;
+    return Vec_PtrEntry( p->vCutsNew, Node );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the linked list of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_NodeReadCutsOld( Cut_Man_t * p, int Node )
+{
+    assert( Node < p->vCutsOld->nSize );
+    return Vec_PtrEntry( p->vCutsOld, Node );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the linked list of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_NodeReadCutsTemp( Cut_Man_t * p, int Node )
+{
+    assert( Node < p->vCutsTemp->nSize );
+    return Vec_PtrEntry( p->vCutsTemp, Node );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the linked list of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeWriteCutsNew( Cut_Man_t * p, int Node, Cut_Cut_t * pList )
+{
+    Vec_PtrWriteEntry( p->vCutsNew, Node, pList );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the linked list of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeWriteCutsOld( Cut_Man_t * p, int Node, Cut_Cut_t * pList )
+{
+    Vec_PtrWriteEntry( p->vCutsOld, Node, pList );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the linked list of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeWriteCutsTemp( Cut_Man_t * p, int Node, Cut_Cut_t * pList )
+{
+    Vec_PtrWriteEntry( p->vCutsTemp, Node, pList );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the trivial cut for the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeSetTriv( Cut_Man_t * p, int Node )
+{
+    assert( Cut_NodeReadCutsNew(p, Node) == NULL );
+    Cut_NodeWriteCutsNew( p, Node, Cut_CutCreateTriv(p, Node) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Consider dropping cuts if they are useless by now.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeTryDroppingCuts( Cut_Man_t * p, int Node )
+{
+    int nFanouts;
+    assert( p->vFanCounts );
+    nFanouts = Vec_IntEntry( p->vFanCounts, Node );
+    assert( nFanouts > 0 );
+    if ( --nFanouts == 0 )
+        Cut_NodeFreeCuts( p, Node );
+    Vec_IntWriteEntry( p->vFanCounts, Node, nFanouts );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deallocates the cuts at the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeFreeCuts( Cut_Man_t * p, int Node )
+{
+    Cut_Cut_t * pList, * pCut, * pCut2;
+    pList = Cut_NodeReadCutsNew( p, Node );
+    if ( pList == NULL )
+        return;
+    Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+        Cut_CutRecycle( p, pCut );
+    Cut_NodeWriteCutsNew( p, Node, NULL );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutCut.c b/src/opt/cut/cutCut.c
new file mode 100644
index 00000000..94147278
--- /dev/null
+++ b/src/opt/cut/cutCut.c
@@ -0,0 +1,359 @@
+/**CFile****************************************************************
+
+  FileName    [cutNode.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Procedures to compute cuts for a node.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutNode.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutAlloc( Cut_Man_t * p )
+{
+    Cut_Cut_t * pCut;
+    // cut allocation
+    pCut = (Cut_Cut_t *)Extra_MmFixedEntryFetch( p->pMmCuts );
+    memset( pCut, 0, sizeof(Cut_Cut_t) );
+    pCut->nVarsMax   = p->pParams->nVarsMax;
+    pCut->fSimul     = p->fSimul;
+    // statistics
+    p->nCutsAlloc++;
+    p->nCutsCur++;
+    if ( p->nCutsPeak < p->nCutsAlloc - p->nCutsDealloc )
+        p->nCutsPeak = p->nCutsAlloc - p->nCutsDealloc;
+    return pCut;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recybles the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CutRecycle( Cut_Man_t * p, Cut_Cut_t * pCut )
+{
+    p->nCutsDealloc++;
+    p->nCutsCur--;
+    if ( pCut->nLeaves == 1 )
+        p->nCutsTriv--;
+    Extra_MmFixedEntryRecycle( p->pMmCuts, (char *)pCut );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compares two cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_CutCompare( Cut_Cut_t * pCut1, Cut_Cut_t * pCut2 )
+{
+    int i;
+    if ( pCut1->nLeaves < pCut2->nLeaves )
+        return -1;
+    if ( pCut1->nLeaves > pCut2->nLeaves )
+        return 1;
+    for ( i = 0; i < (int)pCut1->nLeaves; i++ )
+    {
+        if ( pCut1->pLeaves[i] < pCut2->pLeaves[i] )
+            return -1;
+        if ( pCut1->pLeaves[i] > pCut2->pLeaves[i] )
+            return 1;
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Duplicates the list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutDupList( Cut_Man_t * p, Cut_Cut_t * pList )
+{
+    Cut_Cut_t * pHead = NULL, ** ppTail = &pHead;
+    Cut_Cut_t * pTemp, * pCopy;
+    if ( pList == NULL )
+        return NULL;
+    Cut_ListForEachCut( pList, pTemp )
+    {
+        pCopy = (Cut_Cut_t *)Extra_MmFixedEntryFetch( p->pMmCuts );
+        memcpy( pCopy, pTemp, p->EntrySize );
+        *ppTail = pCopy;
+        ppTail = &pCopy->pNext;
+    }
+    *ppTail = NULL;
+    return pHead;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recycles the list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CutRecycleList( Cut_Man_t * p, Cut_Cut_t * pList )
+{
+    Cut_Cut_t * pCut, * pCut2;
+    Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+        Extra_MmFixedEntryRecycle( p->pMmCuts, (char *)pCut );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of cuts in the list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_CutCountList( Cut_Cut_t * pList )
+{
+    int Counter = 0;
+    Cut_ListForEachCut( pList, pList )
+        Counter++;
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two NULL-terminated linked lists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutMergeLists( Cut_Cut_t * pList1, Cut_Cut_t * pList2 )
+{
+    Cut_Cut_t * pList = NULL, ** ppTail = &pList;
+    Cut_Cut_t * pCut;
+    while ( pList1 && pList2 )
+    {
+        if ( Cut_CutCompare(pList1, pList2) < 0 )
+        {
+            pCut = pList1;
+            pList1 = pList1->pNext;
+        }
+        else
+        {
+            pCut = pList2;
+            pList2 = pList2->pNext;
+        }
+        *ppTail = pCut;
+        ppTail = &pCut->pNext;
+    }
+    *ppTail = pList1? pList1: pList2;
+    return pList;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the number of the cuts in the list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CutNumberList( Cut_Cut_t * pList )
+{
+    Cut_Cut_t * pCut;
+    int i = 0;
+    Cut_ListForEachCut( pList, pCut )
+        pCut->Num0 = i++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the trivial cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutCreateTriv( Cut_Man_t * p, int Node )
+{
+    Cut_Cut_t * pCut;
+    if ( p->pParams->fSeq )
+        Node <<= CUT_SHIFT;
+    pCut = Cut_CutAlloc( p );
+    pCut->nLeaves    = 1;
+    pCut->pLeaves[0] = Node;
+    pCut->uSign      = Cut_NodeSign( Node );
+    if ( p->pParams->fTruth )
+    {
+/*
+        if ( pCut->nVarsMax == 4 )
+            Cut_CutWriteTruth( pCut, p->uTruthVars[0] );
+        else
+            Extra_BitCopy( pCut->nLeaves, p->uTruths[0], (uint8*)Cut_CutReadTruth(pCut) );
+*/
+        unsigned * pTruth = Cut_CutReadTruth(pCut);
+        int i;
+        for ( i = 0; i < p->nTruthWords; i++ )
+            pTruth[i] = 0xAAAAAAAA;
+    }
+    p->nCutsTriv++;
+    return pCut;
+} 
+
+
+/**Function*************************************************************
+
+  Synopsis    [Print the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CutPrint( Cut_Cut_t * pCut, int fSeq )
+{
+    int i;
+    assert( pCut->nLeaves > 0 );
+    printf( "%d : {", pCut->nLeaves );
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+    {
+        if ( fSeq )
+        {
+            printf( " %d", pCut->pLeaves[i] >> CUT_SHIFT );
+            if ( pCut->pLeaves[i] & CUT_MASK )
+                printf( "(%d)", pCut->pLeaves[i] & CUT_MASK );
+        }
+        else
+            printf( " %d", pCut->pLeaves[i] );
+    }
+    printf( " }" );
+//    printf( "\nSign = " );
+//    Extra_PrintBinary( stdout, &pCut->uSign, 32 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Print the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CutPrintList( Cut_Cut_t * pList, int fSeq )
+{
+    Cut_Cut_t * pCut;
+    for ( pCut = pList; pCut; pCut = pCut->pNext )
+        Cut_CutPrint( pCut, fSeq ), printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Consider dropping cuts if they are useless by now.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CutPrintMerge( Cut_Cut_t * pCut, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 )
+{
+    printf( "\n" );
+    printf( "%d : %5d %5d %5d %5d %5d\n", 
+        pCut0->nLeaves, 
+        pCut0->nLeaves > 0 ? pCut0->pLeaves[0] : -1, 
+        pCut0->nLeaves > 1 ? pCut0->pLeaves[1] : -1, 
+        pCut0->nLeaves > 2 ? pCut0->pLeaves[2] : -1, 
+        pCut0->nLeaves > 3 ? pCut0->pLeaves[3] : -1, 
+        pCut0->nLeaves > 4 ? pCut0->pLeaves[4] : -1
+        );
+    printf( "%d : %5d %5d %5d %5d %5d\n", 
+        pCut1->nLeaves, 
+        pCut1->nLeaves > 0 ? pCut1->pLeaves[0] : -1, 
+        pCut1->nLeaves > 1 ? pCut1->pLeaves[1] : -1, 
+        pCut1->nLeaves > 2 ? pCut1->pLeaves[2] : -1, 
+        pCut1->nLeaves > 3 ? pCut1->pLeaves[3] : -1, 
+        pCut1->nLeaves > 4 ? pCut1->pLeaves[4] : -1
+        );
+    if ( pCut == NULL )
+        printf( "Cannot merge\n" );
+    else
+        printf( "%d : %5d %5d %5d %5d %5d\n", 
+            pCut->nLeaves, 
+            pCut->nLeaves > 0 ? pCut->pLeaves[0] : -1, 
+            pCut->nLeaves > 1 ? pCut->pLeaves[1] : -1, 
+            pCut->nLeaves > 2 ? pCut->pLeaves[2] : -1, 
+            pCut->nLeaves > 3 ? pCut->pLeaves[3] : -1, 
+            pCut->nLeaves > 4 ? pCut->pLeaves[4] : -1
+            );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutExpand.c b/src/opt/cut/cutExpand.c
new file mode 100644
index 00000000..d389ef7a
--- /dev/null
+++ b/src/opt/cut/cutExpand.c
@@ -0,0 +1,184 @@
+/**CFile****************************************************************
+
+  FileName    [cutExpand.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Computes the truth table of the cut after expansion.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutExpand.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define CUT_CELL_MVAR  9
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the stretching phase of the cut w.r.t. the merged cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline unsigned Cut_TruthPhase( Cut_Cut_t * pCut, Cut_Cut_t * pCut1 )
+{
+    unsigned uPhase = 0;
+    int i, k;
+    for ( i = k = 0; i < (int)pCut->nLeaves; i++ )
+    {
+        if ( k == (int)pCut1->nLeaves )
+            break;
+        if ( pCut->pLeaves[i] < pCut1->pLeaves[k] )
+            continue;
+        assert( pCut->pLeaves[i] == pCut1->pLeaves[k] );
+        uPhase |= (1 << i);
+        k++;
+    }
+    return uPhase;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth table of the composition of cuts.]
+
+  Description [Inputs are: 
+  - a factor cut (truth table is stored inside)
+  - a node in the factor cut
+  - a tree cut to be substituted (truth table is stored inside)
+  - the resulting cut (truth table will be filled in).
+  Note that all cuts, including the resulting one, should be already 
+  computed and the nodes should be stored in the ascending order.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_TruthCompose( Cut_Cut_t * pCutF, int Node, Cut_Cut_t * pCutT, Cut_Cut_t * pCutRes )
+{
+    static unsigned uCof0[1<<(CUT_CELL_MVAR-5)];
+    static unsigned uCof1[1<<(CUT_CELL_MVAR-5)];
+    static unsigned uTemp[1<<(CUT_CELL_MVAR-5)];
+    unsigned * pIn, * pOut, * pTemp;
+    unsigned uPhase;
+    int NodeIndex, i, k;
+
+    // sanity checks
+    assert( pCutF->nVarsMax == pCutT->nVarsMax );
+    assert( pCutF->nVarsMax == pCutRes->nVarsMax );
+    assert( pCutF->nVarsMax <= CUT_CELL_MVAR );
+    // the factor cut (pCutF) should have its nodes sorted in the ascending order
+    assert( pCutF->nLeaves <= pCutF->nVarsMax );
+    for ( i = 0; i < (int)pCutF->nLeaves - 1; i++ )
+        assert( pCutF->pLeaves[i] < pCutF->pLeaves[i+1] );
+    // the tree cut (pCutT) should have its nodes sorted in the ascending order
+    assert( pCutT->nLeaves <= pCutT->nVarsMax );
+    for ( i = 0; i < (int)pCutT->nLeaves - 1; i++ )
+        assert( pCutT->pLeaves[i] < pCutT->pLeaves[i+1] );
+    // the resulting cut (pCutRes) should have its nodes sorted in the ascending order
+    assert( pCutRes->nLeaves <= pCutRes->nVarsMax );
+    for ( i = 0; i < (int)pCutRes->nLeaves - 1; i++ )
+        assert( pCutRes->pLeaves[i] < pCutRes->pLeaves[i+1] );
+    // make sure that every node in pCutF (except Node) appears in pCutRes
+    for ( i = 0; i < (int)pCutF->nLeaves; i++ )
+    {
+        if ( pCutF->pLeaves[i] == Node )
+            continue;
+        for ( k = 0; k < (int)pCutRes->nLeaves; k++ )
+            if ( pCutF->pLeaves[i] == pCutRes->pLeaves[k] )
+                break;
+        assert( k < (int)pCutRes->nLeaves ); // node i from pCutF is not found in pCutRes!!!
+    }
+    // make sure that every node in pCutT appears in pCutRes
+    for ( i = 0; i < (int)pCutT->nLeaves; i++ )
+    {
+        for ( k = 0; k < (int)pCutRes->nLeaves; k++ )
+            if ( pCutT->pLeaves[i] == pCutRes->pLeaves[k] )
+                break;
+        assert( k < (int)pCutRes->nLeaves ); // node i from pCutT is not found in pCutRes!!!
+    }
+
+
+    // find the index of the given node in the factor cut
+    NodeIndex = -1;
+    for ( NodeIndex = 0; NodeIndex < (int)pCutF->nLeaves; NodeIndex++ )
+        if ( pCutF->pLeaves[NodeIndex] == Node )
+            break;
+    assert( NodeIndex >= 0 );  // Node should be in pCutF
+
+    // copy the truth table
+    Extra_TruthCopy( uTemp, Cut_CutReadTruth(pCutF), pCutF->nLeaves );
+
+    // bubble-move the NodeIndex variable to be the last one (the most significant one)
+    pIn = uTemp; pOut = uCof0; // uCof0 is used for temporary storage here
+    for ( i = NodeIndex; i < (int)pCutF->nLeaves - 1; i++ )
+    {
+        Extra_TruthSwapAdjacentVars( pOut, pIn, pCutF->nLeaves, i );
+        pTemp = pIn; pIn = pOut; pOut = pTemp;
+    }
+    if ( (pCutF->nLeaves - 1 - NodeIndex) & 1 )
+        Extra_TruthCopy( pOut, pIn, pCutF->nLeaves );
+    // the result of stretching is in uTemp
+
+    // cofactor the factor cut with respect to the node
+    Extra_TruthCopy( uCof0, uTemp, pCutF->nLeaves );
+    Extra_TruthCofactor0( uCof0, pCutF->nLeaves, pCutF->nLeaves-1 );
+    Extra_TruthCopy( uCof1, uTemp, pCutF->nLeaves );
+    Extra_TruthCofactor1( uCof1, pCutF->nLeaves, pCutF->nLeaves-1 );
+
+    // temporarily shrink the factor cut's variables by removing Node 
+    for ( i = NodeIndex; i < (int)pCutF->nLeaves - 1; i++ )
+        pCutF->pLeaves[i] = pCutF->pLeaves[i+1];
+    pCutF->nLeaves--;
+
+    // spread out the cofactors' truth tables to the same var order as the resulting cut
+    uPhase = Cut_TruthPhase(pCutRes, pCutF);
+    assert( Extra_WordCountOnes(uPhase) == (int)pCutF->nLeaves );
+    Extra_TruthStretch( uTemp, uCof0, pCutF->nLeaves, pCutF->nVarsMax, uPhase );
+    Extra_TruthCopy( uCof0, uTemp, pCutF->nVarsMax );
+    Extra_TruthStretch( uTemp, uCof1, pCutF->nLeaves, pCutF->nVarsMax, uPhase );
+    Extra_TruthCopy( uCof1, uTemp, pCutF->nVarsMax );
+
+    // spread out the tree cut's truth table to the same var order as the resulting cut
+    uPhase = Cut_TruthPhase(pCutRes, pCutT); 
+    assert( Extra_WordCountOnes(uPhase) == (int)pCutT->nLeaves );
+    Extra_TruthStretch( uTemp, Cut_CutReadTruth(pCutT), pCutT->nLeaves, pCutT->nVarsMax, uPhase );
+
+    // create the resulting truth table
+    pTemp = Cut_CutReadTruth(pCutRes);
+    for ( i = Extra_TruthWordNum(pCutRes->nLeaves)-1; i >= 0; i-- )
+        pTemp[i] = (uCof0[i] & ~uTemp[i]) | (uCof1[i] & uTemp[i]);
+
+    // undo the removal of the node from the cut
+    for ( i = (int)pCutF->nLeaves - 1; i >= NodeIndex; --i )
+        pCutF->pLeaves[i+1] = pCutF->pLeaves[i];
+    pCutF->pLeaves[NodeIndex] = Node;
+    pCutF->nLeaves++;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutInt.h b/src/opt/cut/cutInt.h
new file mode 100644
index 00000000..17f268c7
--- /dev/null
+++ b/src/opt/cut/cutInt.h
@@ -0,0 +1,157 @@
+/**CFile****************************************************************
+
+  FileName    [cutInt.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutInt.h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#ifndef __CUT_INT_H__
+#define __CUT_INT_H__
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include <stdio.h>
+#include "extra.h"
+#include "vec.h"
+#include "cut.h"
+#include "cutList.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Cut_HashTableStruct_t_ Cut_HashTable_t;
+
+struct Cut_ManStruct_t_
+{ 
+    // user preferences
+    Cut_Params_t *     pParams;          // computation parameters
+    Vec_Int_t *        vFanCounts;       // the array of fanout counters
+    Vec_Int_t *        vNodeAttrs;       // node attributes (1 = global; 0 = local)
+    // storage for cuts
+    Vec_Ptr_t *        vCutsNew;         // new cuts by node ID
+    Vec_Ptr_t *        vCutsOld;         // old cuts by node ID
+    Vec_Ptr_t *        vCutsTemp;        // temp cuts for cutset nodes by cutset node number
+    // memory management
+    Extra_MmFixed_t *  pMmCuts;
+    int                EntrySize;
+    int                nTruthWords;
+    // temporary variables
+    Cut_Cut_t *        pReady;
+    Vec_Ptr_t *        vTemp;
+    int                fCompl0;
+    int                fCompl1;
+    int                fSimul;
+    int                nNodeCuts;
+    Cut_Cut_t *        pStore0[2];
+    Cut_Cut_t *        pStore1[2];
+    Cut_Cut_t *        pCompareOld;
+    Cut_Cut_t *        pCompareNew;
+    unsigned *         puTemp[4];
+    // record of the cut computation
+    Vec_Int_t *        vNodeCuts;        // the number of cuts for each node
+    Vec_Int_t *        vNodeStarts;      // the number of the starting cut of each node
+    Vec_Int_t *        vCutPairs;        // the pairs of parent cuts for each cut
+    // minimum delay mapping with the given cuts
+    Vec_Ptr_t *        vCutsMax;
+    Vec_Int_t *        vDelays;
+    Vec_Int_t *        vDelays2;
+    int                nDelayMin;
+    // statistics
+    int                nCutsCur;
+    int                nCutsAlloc;
+    int                nCutsDealloc;
+    int                nCutsPeak;
+    int                nCutsTriv;
+    int                nCutsFilter;
+    int                nCutsLimit;
+    int                nNodes;
+    int                nNodesDag;
+    int                nNodesNoCuts;
+    // runtime
+    int                timeMerge;
+    int                timeUnion;
+    int                timeTruth;
+    int                timeFilter;
+    int                timeHash;
+    int                timeMap;
+};
+
+// iterator through all the cuts of the list
+#define Cut_ListForEachCut( pList, pCut )                 \
+    for ( pCut = pList;                                   \
+          pCut;                                           \
+          pCut = pCut->pNext )
+#define Cut_ListForEachCutStop( pList, pCut, pStop )      \
+    for ( pCut = pList;                                   \
+          pCut != pStop;                                  \
+          pCut = pCut->pNext )
+#define Cut_ListForEachCutSafe( pList, pCut, pCut2 )      \
+    for ( pCut = pList,                                   \
+          pCut2 = pCut? pCut->pNext: NULL;                \
+          pCut;                                           \
+          pCut = pCut2,                                   \
+          pCut2 = pCut? pCut->pNext: NULL )
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+// computes signature of the node
+static inline unsigned Cut_NodeSign( int Node )        { return (1 << (Node % 31));                        }
+static inline int      Cut_TruthWords( int nVarsMax )  { return nVarsMax <= 5 ? 1 : (1 << (nVarsMax - 5)); }
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== cutCut.c ==========================================================*/
+extern Cut_Cut_t *         Cut_CutAlloc( Cut_Man_t * p );
+extern void                Cut_CutRecycle( Cut_Man_t * p, Cut_Cut_t * pCut );
+extern int                 Cut_CutCompare( Cut_Cut_t * pCut1, Cut_Cut_t * pCut2 );
+extern Cut_Cut_t *         Cut_CutDupList( Cut_Man_t * p, Cut_Cut_t * pList );
+extern void                Cut_CutRecycleList( Cut_Man_t * p, Cut_Cut_t * pList );
+extern Cut_Cut_t *         Cut_CutMergeLists( Cut_Cut_t * pList1, Cut_Cut_t * pList2 ); 
+extern void                Cut_CutNumberList( Cut_Cut_t * pList );
+extern Cut_Cut_t *         Cut_CutCreateTriv( Cut_Man_t * p, int Node );
+extern void                Cut_CutPrintMerge( Cut_Cut_t * pCut, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 );
+/*=== cutMerge.c ==========================================================*/
+extern Cut_Cut_t *         Cut_CutMergeTwo( Cut_Man_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 );
+/*=== cutNode.c ==========================================================*/
+extern void                Cut_NodeDoComputeCuts( Cut_Man_t * p, Cut_List_t * pSuper, int Node, int fCompl0, int fCompl1, Cut_Cut_t * pList0, Cut_Cut_t * pList1, int fTriv, int TreeCode ); 
+extern int                 Cut_CutListVerify( Cut_Cut_t * pList );
+/*=== cutTable.c ==========================================================*/
+extern Cut_HashTable_t *   Cut_TableStart( int Size );
+extern void                Cut_TableStop( Cut_HashTable_t * pTable );
+extern int                 Cut_TableLookup( Cut_HashTable_t * pTable, Cut_Cut_t * pCut, int fStore );
+extern void                Cut_TableClear( Cut_HashTable_t * pTable );
+extern int                 Cut_TableReadTime( Cut_HashTable_t * pTable );
+/*=== cutTruth.c ==========================================================*/
+extern void                Cut_TruthComputeOld( Cut_Cut_t * pCut, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1, int fCompl0, int fCompl1 );
+extern void                Cut_TruthCompute( Cut_Man_t * p, Cut_Cut_t * pCut, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1, int fCompl0, int fCompl1 );
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/cut/cutList.h b/src/opt/cut/cutList.h
new file mode 100644
index 00000000..a03ec9d5
--- /dev/null
+++ b/src/opt/cut/cutList.h
@@ -0,0 +1,207 @@
+/**CFile****************************************************************
+
+  FileName    [cutList.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Implementation of layered listed list of cuts.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutList.h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __CUT_LIST_H__
+#define __CUT_LIST_H__
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Cut_ListStruct_t_         Cut_List_t;
+struct Cut_ListStruct_t_
+{
+    Cut_Cut_t *  pHead[CUT_SIZE_MAX+1];
+    Cut_Cut_t ** ppTail[CUT_SIZE_MAX+1];
+};
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Start the cut list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cut_ListStart( Cut_List_t * p )
+{
+    int i;
+    for ( i = 1; i <= CUT_SIZE_MAX; i++ )
+    {
+        p->pHead[i] = 0;
+        p->ppTail[i] = &p->pHead[i];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one cut to the cut list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cut_ListAdd( Cut_List_t * p, Cut_Cut_t * pCut )
+{
+    assert( pCut->nLeaves > 0 && pCut->nLeaves <= CUT_SIZE_MAX );
+    *p->ppTail[pCut->nLeaves] = pCut;
+    p->ppTail[pCut->nLeaves] = &pCut->pNext;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one cut to the cut list while preserving order.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cut_ListAdd2( Cut_List_t * p, Cut_Cut_t * pCut )
+{
+    extern int Cut_CutCompare( Cut_Cut_t * pCut1, Cut_Cut_t * pCut2 );
+    Cut_Cut_t * pTemp, ** ppSpot;
+    assert( pCut->nLeaves > 0 && pCut->nLeaves <= CUT_SIZE_MAX );
+    if ( p->pHead[pCut->nLeaves] != NULL )
+    {
+        ppSpot = &p->pHead[pCut->nLeaves];
+        for ( pTemp = p->pHead[pCut->nLeaves]; pTemp; pTemp = pTemp->pNext )
+        {
+            if ( Cut_CutCompare(pCut, pTemp) < 0 )
+            {
+                *ppSpot = pCut;
+                pCut->pNext = pTemp;
+                return;
+            }
+            else
+                ppSpot = &pTemp->pNext;
+        }
+    }
+    *p->ppTail[pCut->nLeaves] = pCut;
+    p->ppTail[pCut->nLeaves] = &pCut->pNext;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Derive the super list from the linked list of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cut_ListDerive( Cut_List_t * p, Cut_Cut_t * pList )
+{
+    Cut_Cut_t * pPrev;
+    int nLeaves;
+    Cut_ListStart( p );
+    while ( pList != NULL )
+    {
+        nLeaves = pList->nLeaves;
+        p->pHead[nLeaves] = pList;
+        for ( pPrev = pList, pList = pList->pNext; pList; pPrev = pList, pList = pList->pNext )
+            if ( nLeaves < (int)pList->nLeaves )
+                break;
+        p->ppTail[nLeaves] = &pPrev->pNext;
+        pPrev->pNext = NULL;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the second list to the first list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cut_ListAddList( Cut_List_t * pOld, Cut_List_t * pNew )
+{
+    int i;
+    for ( i = 1; i <= CUT_SIZE_MAX; i++ )
+    {
+        if ( pNew->pHead[i] == NULL )
+            continue;
+        *pOld->ppTail[i] = pNew->pHead[i];
+        pOld->ppTail[i] = pNew->ppTail[i];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the cut list linked into one sequence of cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Cut_Cut_t * Cut_ListFinish( Cut_List_t * p )
+{
+    Cut_Cut_t * pHead = NULL, ** ppTail = &pHead;
+    int i;
+    for ( i = 1; i <= CUT_SIZE_MAX; i++ )
+    {
+        if ( p->pHead[i] == NULL )
+            continue;
+        *ppTail = p->pHead[i];
+        ppTail = p->ppTail[i];
+    }
+    *ppTail = NULL;
+    return pHead;
+}
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/cut/cutMan.c b/src/opt/cut/cutMan.c
new file mode 100644
index 00000000..8593ef93
--- /dev/null
+++ b/src/opt/cut/cutMan.c
@@ -0,0 +1,326 @@
+/**CFile****************************************************************
+
+  FileName    [cutMan.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Cut manager.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutMan.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+extern void Npn_StartTruth8( uint8 uTruths[][32] );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the cut manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Man_t * Cut_ManStart( Cut_Params_t * pParams )
+{
+    Cut_Man_t * p;
+    int clk = clock();
+//    extern int nTruthDsd;
+//    nTruthDsd = 0;
+    assert( pParams->nVarsMax >= 3 && pParams->nVarsMax <= CUT_SIZE_MAX );
+    p = ALLOC( Cut_Man_t, 1 );
+    memset( p, 0, sizeof(Cut_Man_t) );
+    // set and correct parameters
+    p->pParams = pParams;
+    // prepare storage for cuts
+    p->vCutsNew = Vec_PtrAlloc( pParams->nIdsMax );
+    Vec_PtrFill( p->vCutsNew, pParams->nIdsMax, NULL );
+    // prepare storage for sequential cuts
+    if ( pParams->fSeq )
+    {
+        p->pParams->fFilter = 1;
+        p->vCutsOld = Vec_PtrAlloc( pParams->nIdsMax );
+        Vec_PtrFill( p->vCutsOld, pParams->nIdsMax, NULL );
+        p->vCutsTemp = Vec_PtrAlloc( pParams->nCutSet );
+        Vec_PtrFill( p->vCutsTemp, pParams->nCutSet, NULL );
+        if ( pParams->fTruth && pParams->nVarsMax > 5 )
+        {
+            pParams->fTruth = 0;
+            printf( "Skipping computation of truth tables for sequential cuts with more than 5 inputs.\n" );
+        }
+    }
+    // entry size
+    p->EntrySize = sizeof(Cut_Cut_t) + pParams->nVarsMax * sizeof(int);
+    if ( pParams->fTruth )
+    {
+        if ( pParams->nVarsMax > 14 )
+        {
+            pParams->fTruth = 0;
+            printf( "Skipping computation of truth table for more than %d inputs.\n", 14 );
+        }
+        else
+        {
+            p->nTruthWords = Cut_TruthWords( pParams->nVarsMax );
+            p->EntrySize += p->nTruthWords * sizeof(unsigned);
+        }
+        p->puTemp[0] = ALLOC( unsigned, 4 * p->nTruthWords );
+        p->puTemp[1] = p->puTemp[0] + p->nTruthWords;
+        p->puTemp[2] = p->puTemp[1] + p->nTruthWords;
+        p->puTemp[3] = p->puTemp[2] + p->nTruthWords;
+    }
+    // enable cut computation recording
+    if ( pParams->fRecord )
+    {
+        p->vNodeCuts   = Vec_IntStart( pParams->nIdsMax );
+        p->vNodeStarts = Vec_IntStart( pParams->nIdsMax );
+        p->vCutPairs   = Vec_IntAlloc( 0 );
+    }
+    // allocate storage for delays
+    if ( pParams->fMap && !p->pParams->fSeq )
+    {
+        p->vDelays = Vec_IntStart( pParams->nIdsMax );
+        p->vDelays2 = Vec_IntStart( pParams->nIdsMax );
+        p->vCutsMax = Vec_PtrStart( pParams->nIdsMax );
+    }
+    // memory for cuts
+    p->pMmCuts = Extra_MmFixedStart( p->EntrySize );
+    p->vTemp = Vec_PtrAlloc( 100 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the cut manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_ManStop( Cut_Man_t * p )
+{
+    Cut_Cut_t * pCut;
+    int i;
+//    extern int nTruthDsd;
+//    printf( "Decomposable cuts = %d.\n", nTruthDsd );
+
+    Vec_PtrForEachEntry( p->vCutsNew, pCut, i )
+        if ( pCut != NULL )
+        {
+            int k = 0;
+        }
+    if ( p->vCutsNew )    Vec_PtrFree( p->vCutsNew );
+    if ( p->vCutsOld )    Vec_PtrFree( p->vCutsOld );
+    if ( p->vCutsTemp )   Vec_PtrFree( p->vCutsTemp );
+    if ( p->vFanCounts )  Vec_IntFree( p->vFanCounts );
+    if ( p->vTemp )       Vec_PtrFree( p->vTemp );
+
+    if ( p->vCutsMax )    Vec_PtrFree( p->vCutsMax );
+    if ( p->vDelays )     Vec_IntFree( p->vDelays );
+    if ( p->vDelays2 )    Vec_IntFree( p->vDelays2 );
+    if ( p->vNodeCuts )   Vec_IntFree( p->vNodeCuts );
+    if ( p->vNodeStarts ) Vec_IntFree( p->vNodeStarts );
+    if ( p->vCutPairs )   Vec_IntFree( p->vCutPairs );
+    if ( p->puTemp[0] )   free( p->puTemp[0] );
+
+    Extra_MmFixedStop( p->pMmCuts );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_ManPrintStats( Cut_Man_t * p )
+{
+    if ( p->pReady )
+    {
+        Cut_CutRecycle( p, p->pReady );
+        p->pReady = NULL;
+    }
+    printf( "Cut computation statistics:\n" );
+    printf( "Current cuts      = %8d. (Trivial = %d.)\n", p->nCutsCur-p->nCutsTriv, p->nCutsTriv );
+    printf( "Peak cuts         = %8d.\n", p->nCutsPeak );
+    printf( "Total allocated   = %8d.\n", p->nCutsAlloc );
+    printf( "Total deallocated = %8d.\n", p->nCutsDealloc );
+    printf( "Cuts filtered     = %8d.\n", p->nCutsFilter );
+    printf( "Nodes saturated   = %8d. (Max cuts = %d.)\n", p->nCutsLimit, p->pParams->nKeepMax );
+    printf( "Cuts per node     = %8.1f\n", ((float)(p->nCutsCur-p->nCutsTriv))/p->nNodes );
+    printf( "The cut size      = %8d bytes.\n", p->EntrySize );
+    printf( "Peak memory       = %8.2f Mb.\n", (float)p->nCutsPeak * p->EntrySize / (1<<20) );
+    printf( "Total nodes       = %8d.\n", p->nNodes );
+    if ( p->pParams->fDag || p->pParams->fTree )
+    {
+    printf( "DAG nodes         = %8d.\n", p->nNodesDag );
+    printf( "Tree nodes        = %8d.\n", p->nNodes - p->nNodesDag );
+    }
+    printf( "Nodes w/o cuts    = %8d.\n", p->nNodesNoCuts );
+    if ( p->pParams->fMap && !p->pParams->fSeq )
+    printf( "Mapping delay     = %8d.\n", p->nDelayMin );
+
+    PRT( "Merge ", p->timeMerge );
+    PRT( "Union ", p->timeUnion );
+    PRT( "Filter", p->timeFilter );
+    PRT( "Truth ", p->timeTruth );
+    PRT( "Map   ", p->timeMap );
+//    printf( "Nodes = %d. Multi = %d.  Cuts = %d. Multi = %d.\n", 
+//        p->nNodes, p->nNodesMulti, p->nCutsCur-p->nCutsTriv, p->nCutsMulti );
+//    printf( "Count0 = %d. Count1 = %d. Count2 = %d.\n\n", p->Count0, p->Count1, p->Count2 );
+}
+
+    
+/**Function*************************************************************
+
+  Synopsis    [Prints some interesting stats.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_ManPrintStatsToFile( Cut_Man_t * p, char * pFileName, int TimeTotal )
+{
+    FILE * pTable;
+    pTable = fopen( "cut_stats.txt", "a+" );
+    fprintf( pTable, "%-20s ", pFileName );
+    fprintf( pTable, "%8d ", p->nNodes );
+    fprintf( pTable, "%6.1f ", ((float)(p->nCutsCur))/p->nNodes );
+    fprintf( pTable, "%6.2f ", ((float)(100.0 * p->nCutsLimit))/p->nNodes );
+    fprintf( pTable, "%6.2f ", (float)p->nCutsPeak * p->EntrySize / (1<<20) );
+    fprintf( pTable, "%6.2f ", (float)(TimeTotal)/(float)(CLOCKS_PER_SEC) );
+    fprintf( pTable, "\n" );
+    fclose( pTable );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_ManSetFanoutCounts( Cut_Man_t * p, Vec_Int_t * vFanCounts )
+{
+    p->vFanCounts = vFanCounts;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_ManSetNodeAttrs( Cut_Man_t * p, Vec_Int_t * vNodeAttrs )
+{
+    p->vNodeAttrs = vNodeAttrs;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_ManReadVarsMax( Cut_Man_t * p )
+{
+    return p->pParams->nVarsMax;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Params_t * Cut_ManReadParams( Cut_Man_t * p )
+{
+    return p->pParams;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Cut_ManReadNodeAttrs( Cut_Man_t * p )
+{
+    return p->vNodeAttrs;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_ManIncrementDagNodes( Cut_Man_t * p )
+{
+    p->nNodesDag++;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutMerge.c b/src/opt/cut/cutMerge.c
new file mode 100644
index 00000000..d8a9989c
--- /dev/null
+++ b/src/opt/cut/cutMerge.c
@@ -0,0 +1,657 @@
+/**CFile****************************************************************
+
+  FileName    [cutMerge.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Procedure to merge two cuts.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutMerge.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two cuts.]
+
+  Description [This procedure works.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutMergeTwo2( Cut_Man_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 )
+{ 
+    static int M[7][3] = {{0},{0},{0},{0},{0},{0},{0}};
+    Cut_Cut_t * pRes;
+    int * pRow;
+    int nLeaves0, nLeaves1, Limit;
+    int i, k, Count, nNodes;
+
+    assert( pCut0->nLeaves >= pCut1->nLeaves );
+
+    // the case of the largest cut sizes
+    Limit = p->pParams->nVarsMax;
+    nLeaves0 = pCut0->nLeaves;
+    nLeaves1 = pCut1->nLeaves;
+    if ( nLeaves0 == Limit && nLeaves1 == Limit )
+    {
+        for ( i = 0; i < nLeaves0; i++ )
+            if ( pCut0->pLeaves[i] != pCut1->pLeaves[i] )
+                return NULL;
+        pRes = Cut_CutAlloc( p );
+        for ( i = 0; i < nLeaves0; i++ )
+            pRes->pLeaves[i] = pCut0->pLeaves[i];
+        pRes->nLeaves = nLeaves0;
+        return pRes;
+    }
+    // the case when one of the cuts is the largest
+    if ( nLeaves0 == Limit )
+    {
+        for ( i = 0; i < nLeaves1; i++ )
+        {
+            for ( k = nLeaves0 - 1; k >= 0; k-- )
+                if ( pCut0->pLeaves[k] == pCut1->pLeaves[i] )
+                    break;
+            if ( k == -1 ) // did not find
+                return NULL;
+        }
+        pRes = Cut_CutAlloc( p );
+        for ( i = 0; i < nLeaves0; i++ )
+            pRes->pLeaves[i] = pCut0->pLeaves[i];
+        pRes->nLeaves = nLeaves0;
+        return pRes;
+    }
+    // other cases
+    nNodes = nLeaves0;
+    for ( i = 0; i < nLeaves1; i++ )
+    {
+        for ( k = nLeaves0 - 1; k >= 0; k-- )
+        {
+            if ( pCut0->pLeaves[k] > pCut1->pLeaves[i] )
+                continue;
+            if ( pCut0->pLeaves[k] < pCut1->pLeaves[i] )
+            {
+                pRow = M[k+1];
+                if ( pRow[0] == 0 )
+                    pRow[0] = pCut1->pLeaves[i], pRow[1] = 0;
+                else if ( pRow[1] == 0 )
+                    pRow[1] = pCut1->pLeaves[i], pRow[2] = 0;
+                else if ( pRow[2] == 0 )
+                    pRow[2] = pCut1->pLeaves[i];
+                else 
+                    assert( 0 );
+                if ( ++nNodes > Limit )
+                {
+                    for ( i = 0; i <= nLeaves0; i++ )
+                        M[i][0] = 0;
+                    return NULL;
+                }
+            }
+            break;
+        }
+        if ( k == -1 )
+        {
+            pRow = M[0];
+            if ( pRow[0] == 0 )
+                pRow[0] = pCut1->pLeaves[i], pRow[1] = 0;
+            else if ( pRow[1] == 0 )
+                pRow[1] = pCut1->pLeaves[i], pRow[2] = 0;
+            else if ( pRow[2] == 0 )
+                pRow[2] = pCut1->pLeaves[i];
+            else 
+                assert( 0 );
+            if ( ++nNodes > Limit )
+            {
+                for ( i = 0; i <= nLeaves0; i++ )
+                    M[i][0] = 0;
+                return NULL;
+            }
+            continue;
+        }
+    }
+
+    pRes = Cut_CutAlloc( p );
+    for ( Count = 0, i = 0; i <= nLeaves0; i++ )
+    {
+        if ( i > 0 )
+            pRes->pLeaves[Count++] = pCut0->pLeaves[i-1];
+        pRow = M[i];
+        if ( pRow[0] )
+        {
+            pRes->pLeaves[Count++] = pRow[0];
+            if ( pRow[1] )
+            {
+                pRes->pLeaves[Count++] = pRow[1];
+                if ( pRow[2] )
+                    pRes->pLeaves[Count++] = pRow[2];
+            }
+            pRow[0] = 0;
+        }
+    }
+    assert( Count == nNodes );
+    pRes->nLeaves = nNodes;
+    return pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutMergeTwo( Cut_Man_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 )
+{ 
+    Cut_Cut_t * pRes;
+    int * pLeaves;
+    int Limit, nLeaves0, nLeaves1;
+    int i, k, c;
+
+    assert( pCut0->nLeaves >= pCut1->nLeaves );
+
+    // consider two cuts
+    nLeaves0 = pCut0->nLeaves;
+    nLeaves1 = pCut1->nLeaves;
+
+    // the case of the largest cut sizes
+    Limit = p->pParams->nVarsMax;
+    if ( nLeaves0 == Limit && nLeaves1 == Limit )
+    {
+        for ( i = 0; i < nLeaves0; i++ )
+            if ( pCut0->pLeaves[i] != pCut1->pLeaves[i] )
+                return NULL;
+        pRes = Cut_CutAlloc( p );
+        for ( i = 0; i < nLeaves0; i++ )
+            pRes->pLeaves[i] = pCut0->pLeaves[i];
+        pRes->nLeaves = pCut0->nLeaves;
+        return pRes;
+    }
+    // the case when one of the cuts is the largest
+    if ( nLeaves0 == Limit )
+    {
+        for ( i = 0; i < nLeaves1; i++ )
+        {
+            for ( k = nLeaves0 - 1; k >= 0; k-- )
+                if ( pCut0->pLeaves[k] == pCut1->pLeaves[i] )
+                    break;
+            if ( k == -1 ) // did not find
+                return NULL;
+        }
+        pRes = Cut_CutAlloc( p );
+        for ( i = 0; i < nLeaves0; i++ )
+            pRes->pLeaves[i] = pCut0->pLeaves[i];
+        pRes->nLeaves = pCut0->nLeaves;
+        return pRes;
+    }
+
+    // prepare the cut
+    if ( p->pReady == NULL )
+        p->pReady = Cut_CutAlloc( p );
+    pLeaves = p->pReady->pLeaves;
+
+    // compare two cuts with different numbers
+    i = k = 0;
+    for ( c = 0; c < Limit; c++ )
+    {
+        if ( k == nLeaves1 )
+        {
+            if ( i == nLeaves0 )
+            {
+                p->pReady->nLeaves = c;
+                pRes = p->pReady;  p->pReady = NULL;
+                return pRes;
+            }
+            pLeaves[c] = pCut0->pLeaves[i++];
+            continue;
+        }
+        if ( i == nLeaves0 )
+        {
+            if ( k == nLeaves1 )
+            {
+                p->pReady->nLeaves = c;
+                pRes = p->pReady;  p->pReady = NULL;
+                return pRes;
+            }
+            pLeaves[c] = pCut1->pLeaves[k++];
+            continue;
+        }
+        if ( pCut0->pLeaves[i] < pCut1->pLeaves[k] )
+        {
+            pLeaves[c] = pCut0->pLeaves[i++];
+            continue;
+        }
+        if ( pCut0->pLeaves[i] > pCut1->pLeaves[k] )
+        {
+            pLeaves[c] = pCut1->pLeaves[k++];
+            continue;
+        }
+        pLeaves[c] = pCut0->pLeaves[i++]; 
+        k++;
+    }
+    if ( i < nLeaves0 || k < nLeaves1 )
+        return NULL;
+    p->pReady->nLeaves = c;
+    pRes = p->pReady;  p->pReady = NULL;
+    return pRes;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutMergeTwo3( Cut_Man_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 )
+{ 
+    Cut_Cut_t * pRes;
+    int * pLeaves;
+    int Limit, nLeaves0, nLeaves1;
+    int i, k, c;
+
+    assert( pCut0->nLeaves >= pCut1->nLeaves );
+
+    // prepare the cut
+    if ( p->pReady == NULL )
+        p->pReady = Cut_CutAlloc( p );
+    pLeaves = p->pReady->pLeaves;
+
+    // consider two cuts
+    Limit = p->pParams->nVarsMax;
+    nLeaves0 = pCut0->nLeaves;
+    nLeaves1 = pCut1->nLeaves;
+    if ( nLeaves0 == Limit )
+    { // the case when one of the cuts is the largest
+        if ( nLeaves1 == Limit )
+        { // the case when both cuts are the largest
+            for ( i = 0; i < nLeaves0; i++ )
+            {
+                pLeaves[i] = pCut0->pLeaves[i];
+                if ( pLeaves[i] != pCut1->pLeaves[i] )
+                    return NULL;
+            }
+        }
+        else
+        {
+            for ( i = k = 0; i < nLeaves0; i++ )
+            {
+                pLeaves[i] = pCut0->pLeaves[i];
+                if ( k == (int)nLeaves1 )
+                    continue;
+                if ( pLeaves[i] < pCut1->pLeaves[k] )
+                    continue;
+                if ( pLeaves[i] == pCut1->pLeaves[k++] )
+                    continue;
+                return NULL;
+            }
+            if ( k < nLeaves1 )
+                return NULL;
+        }
+        p->pReady->nLeaves = nLeaves0;
+        pRes = p->pReady;  p->pReady = NULL;
+        return pRes;
+    }
+
+    // compare two cuts with different numbers
+    i = k = 0;
+    for ( c = 0; c < Limit; c++ )
+    {
+        if ( k == nLeaves1 )
+        {
+            if ( i == nLeaves0 )
+            {
+                p->pReady->nLeaves = c;
+                pRes = p->pReady;  p->pReady = NULL;
+                return pRes;
+            }
+            pLeaves[c] = pCut0->pLeaves[i++];
+            continue;
+        }
+        if ( i == nLeaves0 )
+        {
+            if ( k == nLeaves1 )
+            {
+                p->pReady->nLeaves = c;
+                pRes = p->pReady;  p->pReady = NULL;
+                return pRes;
+            }
+            pLeaves[c] = pCut1->pLeaves[k++];
+            continue;
+        }
+        if ( pCut0->pLeaves[i] < pCut1->pLeaves[k] )
+        {
+            pLeaves[c] = pCut0->pLeaves[i++];
+            continue;
+        }
+        if ( pCut0->pLeaves[i] > pCut1->pLeaves[k] )
+        {
+            pLeaves[c] = pCut1->pLeaves[k++];
+            continue;
+        }
+        pLeaves[c] = pCut0->pLeaves[i++]; 
+        k++;
+    }
+    if ( i < nLeaves0 || k < nLeaves1 )
+        return NULL;
+    p->pReady->nLeaves = c;
+    pRes = p->pReady;  p->pReady = NULL;
+    return pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutMergeTwo4( Cut_Man_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 )
+{ 
+    Cut_Cut_t * pRes;
+    int * pLeaves;
+    int i, k, min, NodeTemp, Limit, nTotal;
+
+    assert( pCut0->nLeaves >= pCut1->nLeaves );
+
+    // prepare the cut
+    if ( p->pReady == NULL )
+        p->pReady = Cut_CutAlloc( p );
+    pLeaves = p->pReady->pLeaves;
+
+    // consider two cuts
+    Limit = p->pParams->nVarsMax;
+    if ( pCut0->nLeaves == (unsigned)Limit )
+    { // the case when one of the cuts is the largest
+        if ( pCut1->nLeaves == (unsigned)Limit )
+        { // the case when both cuts are the largest
+            for ( i = 0; i < (int)pCut0->nLeaves; i++ )
+            {
+                pLeaves[i] = pCut0->pLeaves[i];
+                if ( pLeaves[i] != pCut1->pLeaves[i] )
+                    return NULL;
+            }
+        }
+        else
+        {
+            for ( i = k = 0; i < (int)pCut0->nLeaves; i++ )
+            {
+                pLeaves[i] = pCut0->pLeaves[i];
+                if ( k == (int)pCut1->nLeaves )
+                    continue;
+                if ( pLeaves[i] < pCut1->pLeaves[k] )
+                    continue;
+                if ( pLeaves[i] == pCut1->pLeaves[k++] )
+                    continue;
+                return NULL;
+            }
+            if ( k < (int)pCut1->nLeaves )
+                return NULL;
+        }
+        p->pReady->nLeaves = pCut0->nLeaves;
+        pRes = p->pReady;  p->pReady = NULL;
+        return pRes;
+    }
+
+    // count the number of unique entries in pCut1
+    nTotal = pCut0->nLeaves;
+    for ( i = 0; i < (int)pCut1->nLeaves; i++ )
+    {
+        // try to find this entry among the leaves of pCut0
+        for ( k = 0; k < (int)pCut0->nLeaves; k++ )
+            if ( pCut1->pLeaves[i] == pCut0->pLeaves[k] )
+                break;
+        if ( k < (int)pCut0->nLeaves ) // found
+            continue;
+        // we found a new entry to add
+        if ( nTotal == Limit )
+            return NULL;
+        pLeaves[nTotal++] = pCut1->pLeaves[i];
+    }
+    // we know that the feasible cut exists
+
+    // add the starting entries
+    for ( k = 0; k < (int)pCut0->nLeaves; k++ )
+        pLeaves[k] = pCut0->pLeaves[k];
+
+    // selection-sort the entries
+    for ( i = 0; i < nTotal - 1; i++ )
+    {
+        min = i;
+        for ( k = i+1; k < nTotal; k++ )
+            if ( pLeaves[k] < pLeaves[min] )
+                min = k;
+        NodeTemp     = pLeaves[i];
+        pLeaves[i]   = pLeaves[min];
+        pLeaves[min] = NodeTemp;
+    }
+    p->pReady->nLeaves = nTotal;
+    pRes = p->pReady;  p->pReady = NULL;
+    return pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two cuts.]
+
+  Description [This procedure works.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutMergeTwo5( Cut_Man_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 )
+{ 
+    static int M[7][3] = {{0},{0},{0},{0},{0},{0},{0}};
+    Cut_Cut_t * pRes;
+    int * pRow;
+    unsigned uSign0, uSign1;
+    int i, k, nNodes, Count;
+    unsigned Limit = p->pParams->nVarsMax;
+
+    assert( pCut0->nLeaves >= pCut1->nLeaves );
+
+    // the case of the largest cut sizes
+    if ( pCut0->nLeaves == Limit && pCut1->nLeaves == Limit )
+    {
+        for ( i = 0; i < (int)pCut0->nLeaves; i++ )
+            if ( pCut0->pLeaves[i] != pCut1->pLeaves[i] )
+                return NULL;
+        pRes = Cut_CutAlloc( p );
+        for ( i = 0; i < (int)pCut0->nLeaves; i++ )
+            pRes->pLeaves[i] = pCut0->pLeaves[i];
+        pRes->nLeaves = pCut0->nLeaves;
+        return pRes;
+    }
+    // the case when one of the cuts is the largest
+    if ( pCut0->nLeaves == Limit )
+    {
+        if ( !p->pParams->fTruth )
+        {
+            for ( i = 0; i < (int)pCut1->nLeaves; i++ )
+            {
+                for ( k = pCut0->nLeaves - 1; k >= 0; k-- )
+                    if ( pCut0->pLeaves[k] == pCut1->pLeaves[i] )
+                        break;
+                if ( k == -1 ) // did not find
+                    return NULL;
+            }
+            pRes = Cut_CutAlloc( p );
+        }
+        else
+        {
+            uSign1 = 0;
+            for ( i = 0; i < (int)pCut1->nLeaves; i++ )
+            {
+                for ( k = pCut0->nLeaves - 1; k >= 0; k-- )
+                    if ( pCut0->pLeaves[k] == pCut1->pLeaves[i] )
+                    {
+                        uSign1 |= (1 << i);
+                        break;
+                    }
+                if ( k == -1 ) // did not find
+                    return NULL;
+            }
+            pRes = Cut_CutAlloc( p );
+            pRes->Num1 = uSign1;
+        }
+        for ( i = 0; i < (int)pCut0->nLeaves; i++ )
+            pRes->pLeaves[i] = pCut0->pLeaves[i];
+        pRes->nLeaves = pCut0->nLeaves;
+        return pRes;
+    }
+    // other cases
+    nNodes = pCut0->nLeaves;
+    for ( i = 0; i < (int)pCut1->nLeaves; i++ )
+    {
+        for ( k = pCut0->nLeaves - 1; k >= 0; k-- )
+        {
+            if ( pCut0->pLeaves[k] > pCut1->pLeaves[i] )
+                continue;
+            if ( pCut0->pLeaves[k] < pCut1->pLeaves[i] )
+            {
+                pRow = M[k+1];
+                if ( pRow[0] == 0 )
+                    pRow[0] = pCut1->pLeaves[i], pRow[1] = 0;
+                else if ( pRow[1] == 0 )
+                    pRow[1] = pCut1->pLeaves[i], pRow[2] = 0;
+                else if ( pRow[2] == 0 )
+                    pRow[2] = pCut1->pLeaves[i];
+                else 
+                    assert( 0 );
+                if ( ++nNodes > (int)Limit )
+                {
+                    for ( i = 0; i <= (int)pCut0->nLeaves; i++ )
+                        M[i][0] = 0;
+                    return NULL;
+                }
+            }
+            break;
+        }
+        if ( k == -1 )
+        {
+            pRow = M[0];
+            if ( pRow[0] == 0 )
+                pRow[0] = pCut1->pLeaves[i], pRow[1] = 0;
+            else if ( pRow[1] == 0 )
+                pRow[1] = pCut1->pLeaves[i], pRow[2] = 0;
+            else if ( pRow[2] == 0 )
+                pRow[2] = pCut1->pLeaves[i];
+            else 
+                assert( 0 );
+            if ( ++nNodes > (int)Limit )
+            {
+                for ( i = 0; i <= (int)pCut0->nLeaves; i++ )
+                    M[i][0] = 0;
+                return NULL;
+            }
+            continue;
+        }
+    }
+
+    pRes = Cut_CutAlloc( p );
+    if ( !p->pParams->fTruth )
+    {
+        for ( Count = 0, i = 0; i <= (int)pCut0->nLeaves; i++ )
+        {
+            if ( i > 0 )
+                pRes->pLeaves[Count++] = pCut0->pLeaves[i-1];
+            pRow = M[i];
+            if ( pRow[0] )
+            {
+                pRes->pLeaves[Count++] = pRow[0];
+                if ( pRow[1] )
+                {
+                    pRes->pLeaves[Count++] = pRow[1];
+                    if ( pRow[2] )
+                        pRes->pLeaves[Count++] = pRow[2];
+                }
+                pRow[0] = 0;
+            }
+        }
+        assert( Count == nNodes );
+        pRes->nLeaves = nNodes;
+/*
+    // make sure that the cut is correct
+    {
+        for ( i = 1; i < (int)pRes->nLeaves; i++ )
+            if ( pRes->pLeaves[i-1] >= pRes->pLeaves[i] )
+            {
+                int v = 0;
+            }
+    }
+*/
+        return pRes;
+    }
+
+    uSign0 = uSign1 = 0;
+    for ( Count = 0, i = 0; i <= (int)pCut0->nLeaves; i++ )
+    {
+        if ( i > 0 )
+        {
+            uSign0 |= (1 << Count);
+            pRes->pLeaves[Count++] = pCut1->pLeaves[i-1];
+        }
+        pRow = M[i];
+        if ( pRow[0] )
+        {
+            uSign1 |= (1 << Count);
+            pRes->pLeaves[Count++] = pRow[0];
+            if ( pRow[1] )
+            {
+                uSign1 |= (1 << Count);
+                pRes->pLeaves[Count++] = pRow[1];
+                if ( pRow[2] )
+                {
+                    uSign1 |= (1 << Count);
+                    pRes->pLeaves[Count++] = pRow[2];
+                }
+            }
+            pRow[0] = 0;
+        }
+    }
+    assert( Count == nNodes );
+    pRes->nLeaves = nNodes;
+    pRes->Num1 = uSign1;
+    pRes->Num0 = uSign0;
+    return pRes;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutNode.c b/src/opt/cut/cutNode.c
new file mode 100644
index 00000000..1f93b14b
--- /dev/null
+++ b/src/opt/cut/cutNode.c
@@ -0,0 +1,992 @@
+/**CFile****************************************************************
+
+  FileName    [cutNode.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Procedures to compute cuts for a node.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutNode.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Cut_NodeMapping( Cut_Man_t * p, Cut_Cut_t * pCuts, int Node, int Node0, int Node1 );
+static int Cut_NodeMapping2( Cut_Man_t * p, Cut_Cut_t * pCuts, int Node, int Node0, int Node1 );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if pDom is contained in pCut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cut_CutCheckDominance( Cut_Cut_t * pDom, Cut_Cut_t * pCut )
+{
+    int i, k;
+    for ( i = 0; i < (int)pDom->nLeaves; i++ )
+    {
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+            if ( pDom->pLeaves[i] == pCut->pLeaves[k] )
+                break;
+        if ( k == (int)pCut->nLeaves ) // node i in pDom is not contained in pCut
+            return 0;
+    }
+    // every node in pDom is contained in pCut
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Filters cuts using dominance.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cut_CutFilter( Cut_Man_t * p, Cut_Cut_t * pList )
+{ 
+    Cut_Cut_t * pListR, ** ppListR = &pListR;
+    Cut_Cut_t * pCut, * pCut2, * pDom, * pPrev;
+    // save the first cut
+    *ppListR = pList, ppListR = &pList->pNext;
+    // try to filter out other cuts
+    pPrev = pList;
+    Cut_ListForEachCutSafe( pList->pNext, pCut, pCut2 )
+    {
+        assert( pCut->nLeaves > 1 );
+        // go through all the previous cuts up to pCut
+        Cut_ListForEachCutStop( pList->pNext, pDom, pCut )
+        {
+            if ( pDom->nLeaves > pCut->nLeaves )
+                continue;
+            if ( (pDom->uSign & pCut->uSign) != pDom->uSign )
+                continue;
+            if ( Cut_CutCheckDominance( pDom, pCut ) )
+                break;
+        }
+        if ( pDom != pCut ) // pDom is contained in pCut - recycle pCut
+        {
+            // make sure cuts are connected after removing
+            pPrev->pNext = pCut->pNext;
+            // recycle the cut
+            Cut_CutRecycle( p, pCut );
+        }
+        else // pDom is NOT contained in pCut - save pCut
+        {
+            *ppListR = pCut, ppListR = &pCut->pNext;
+            pPrev = pCut;
+        }
+    }
+    *ppListR = NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks equality of one cut.]
+
+  Description [Returns 1 if the cut is removed.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cut_CutFilterOneEqual( Cut_Man_t * p, Cut_List_t * pSuperList, Cut_Cut_t * pCut )
+{
+    Cut_Cut_t * pTemp;
+    Cut_ListForEachCut( pSuperList->pHead[pCut->nLeaves], pTemp )
+    {
+        // skip the non-contained cuts
+        if ( pCut->uSign != pTemp->uSign )
+            continue;
+        // check containment seriously
+        if ( Cut_CutCheckDominance( pTemp, pCut ) )
+        {
+            p->nCutsFilter++;
+            Cut_CutRecycle( p, pCut );
+            return 1;
+        }
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks containment for one cut.]
+
+  Description [Returns 1 if the cut is removed.]
+               
+  SideEffects [May remove other cuts in the set.]
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cut_CutFilterOne( Cut_Man_t * p, Cut_List_t * pSuperList, Cut_Cut_t * pCut )
+{
+    Cut_Cut_t * pTemp, * pTemp2, ** ppTail;
+    int a;
+
+    // check if this cut is filtered out by smaller cuts
+    for ( a = 2; a <= (int)pCut->nLeaves; a++ )
+    {
+        Cut_ListForEachCut( pSuperList->pHead[a], pTemp )
+        {
+            // skip the non-contained cuts
+            if ( (pTemp->uSign & pCut->uSign) != pTemp->uSign )
+                continue;
+            // check containment seriously
+            if ( Cut_CutCheckDominance( pTemp, pCut ) )
+            {
+                p->nCutsFilter++;
+                Cut_CutRecycle( p, pCut );
+                return 1;
+            }
+        }
+    }
+
+    // filter out other cuts using this one
+    for ( a = pCut->nLeaves + 1; a <= (int)pCut->nVarsMax; a++ )
+    {
+        ppTail = pSuperList->pHead + a;
+        Cut_ListForEachCutSafe( pSuperList->pHead[a], pTemp, pTemp2 )
+        {
+            // skip the non-contained cuts
+            if ( (pTemp->uSign & pCut->uSign) != pCut->uSign )
+            {
+                ppTail = &pTemp->pNext;
+                continue;
+            }
+            // check containment seriously
+            if ( Cut_CutCheckDominance( pCut, pTemp ) )
+            {
+                p->nCutsFilter++;
+                p->nNodeCuts--;
+                // move the head
+                if ( pSuperList->pHead[a] == pTemp )
+                    pSuperList->pHead[a] = pTemp->pNext;
+                // move the tail
+                if ( pSuperList->ppTail[a] == &pTemp->pNext )
+                    pSuperList->ppTail[a] = ppTail;
+                // skip the given cut in the list
+                *ppTail = pTemp->pNext;
+                // recycle pTemp
+                Cut_CutRecycle( p, pTemp );
+            }
+            else
+                ppTail = &pTemp->pNext;
+        }
+        assert( ppTail == pSuperList->ppTail[a] );
+        assert( *ppTail == NULL );
+    }
+
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks if the cut is local and can be removed.]
+
+  Description [Returns 1 if the cut is removed.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cut_CutFilterGlobal( Cut_Man_t * p, Cut_Cut_t * pCut )
+{
+    int a;
+    if ( pCut->nLeaves == 1 )
+        return 0;
+    for ( a = 0; a < (int)pCut->nLeaves; a++ )
+        if ( Vec_IntEntry( p->vNodeAttrs, pCut->pLeaves[a] ) ) // global
+            return 0;
+    // there is no global nodes, the cut should be removed
+    p->nCutsFilter++;
+    Cut_CutRecycle( p, pCut );
+    return 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Checks containment for one cut.]
+
+  Description [Returns 1 if the cut is removed.]
+               
+  SideEffects [May remove other cuts in the set.]
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cut_CutFilterOld( Cut_Man_t * p, Cut_Cut_t * pList, Cut_Cut_t * pCut )
+{
+    Cut_Cut_t * pPrev, * pTemp, * pTemp2, ** ppTail;
+
+    // check if this cut is filtered out by smaller cuts
+    pPrev = NULL;
+    Cut_ListForEachCut( pList, pTemp )
+    {
+        if ( pTemp->nLeaves > pCut->nLeaves )
+            break;
+        pPrev = pTemp;
+        // skip the non-contained cuts
+        if ( (pTemp->uSign & pCut->uSign) != pTemp->uSign )
+            continue;
+        // check containment seriously
+        if ( Cut_CutCheckDominance( pTemp, pCut ) )
+        {
+            p->nCutsFilter++;
+            Cut_CutRecycle( p, pCut );
+            return 1;
+        }
+    }
+    assert( pPrev->pNext == pTemp );
+
+    // filter out other cuts using this one
+    ppTail = &pPrev->pNext;
+    Cut_ListForEachCutSafe( pTemp, pTemp, pTemp2 )
+    {
+        // skip the non-contained cuts
+        if ( (pTemp->uSign & pCut->uSign) != pCut->uSign )
+        {
+            ppTail = &pTemp->pNext;
+            continue;
+        }
+        // check containment seriously
+        if ( Cut_CutCheckDominance( pCut, pTemp ) )
+        {
+            p->nCutsFilter++;
+            p->nNodeCuts--;
+            // skip the given cut in the list
+            *ppTail = pTemp->pNext;
+            // recycle pTemp
+            Cut_CutRecycle( p, pTemp );
+        }
+        else
+            ppTail = &pTemp->pNext;
+    }
+    assert( *ppTail == NULL );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Processes two cuts.]
+
+  Description [Returns 1 if the limit has been reached.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cut_CutProcessTwo( Cut_Man_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1, Cut_List_t * pSuperList )
+{
+    Cut_Cut_t * pCut;
+    // merge the cuts
+    if ( pCut0->nLeaves >= pCut1->nLeaves )
+        pCut = Cut_CutMergeTwo( p, pCut0, pCut1 );
+    else
+        pCut = Cut_CutMergeTwo( p, pCut1, pCut0 );
+    if ( pCut == NULL )
+        return 0;
+    assert( p->pParams->fSeq || pCut->nLeaves > 1 );
+    // set the signature
+    pCut->uSign = pCut0->uSign | pCut1->uSign;
+    if ( p->pParams->fRecord )
+        pCut->Num0 = pCut0->Num0, pCut->Num1 = pCut1->Num0;
+    // check containment
+    if ( p->pParams->fFilter )
+    {
+        if ( Cut_CutFilterOne(p, pSuperList, pCut) )
+//        if ( Cut_CutFilterOneEqual(p, pSuperList, pCut) )
+            return 0;
+        if ( p->pParams->fSeq )
+        {
+            if ( p->pCompareOld && Cut_CutFilterOld(p, p->pCompareOld, pCut) )
+                return 0;
+            if ( p->pCompareNew && Cut_CutFilterOld(p, p->pCompareNew, pCut) )
+                return 0;
+        }
+    }
+
+    if ( p->pParams->fGlobal )
+    {
+        assert( p->vNodeAttrs != NULL );
+        if ( Cut_CutFilterGlobal( p, pCut ) )
+            return 0;
+    }
+
+    // compute the truth table
+    if ( p->pParams->fTruth )
+        Cut_TruthCompute( p, pCut, pCut0, pCut1, p->fCompl0, p->fCompl1 );
+    // add to the list
+    Cut_ListAdd( pSuperList, pCut );
+    // return status (0 if okay; 1 if exceeded the limit)
+    return ++p->nNodeCuts == p->pParams->nKeepMax;
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts by merging cuts at two nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_NodeComputeCuts( Cut_Man_t * p, int Node, int Node0, int Node1, int fCompl0, int fCompl1, int fTriv, int TreeCode )
+{
+    Cut_List_t Super, * pSuper = &Super;
+    Cut_Cut_t * pList, * pCut;
+    int clk;
+    // start the number of cuts at the node
+    p->nNodes++;
+    p->nNodeCuts = 0;
+    // prepare information for recording
+    if ( p->pParams->fRecord )
+    {
+        Cut_CutNumberList( Cut_NodeReadCutsNew(p, Node0) );
+        Cut_CutNumberList( Cut_NodeReadCutsNew(p, Node1) );
+    }
+    // compute the cuts
+clk = clock();
+    Cut_ListStart( pSuper );
+    Cut_NodeDoComputeCuts( p, pSuper, Node, fCompl0, fCompl1, Cut_NodeReadCutsNew(p, Node0), Cut_NodeReadCutsNew(p, Node1), fTriv, TreeCode );
+    pList = Cut_ListFinish( pSuper );
+p->timeMerge += clock() - clk;
+    // verify the result of cut computation
+//    Cut_CutListVerify( pList );
+    // performing the recording
+    if ( p->pParams->fRecord )
+    {
+        Vec_IntWriteEntry( p->vNodeStarts, Node, Vec_IntSize(p->vCutPairs) );
+        Cut_ListForEachCut( pList, pCut )
+            Vec_IntPush( p->vCutPairs, ((pCut->Num1 << 16) | pCut->Num0) );
+        Vec_IntWriteEntry( p->vNodeCuts, Node, Vec_IntSize(p->vCutPairs) - Vec_IntEntry(p->vNodeStarts, Node) );
+    }
+    // check if the node is over the list
+    if ( p->nNodeCuts == p->pParams->nKeepMax )
+        p->nCutsLimit++;
+    // set the list at the node
+    Vec_PtrFillExtra( p->vCutsNew, Node + 1, NULL );
+    assert( Cut_NodeReadCutsNew(p, Node) == NULL );
+    /////
+//    pList->pNext = NULL;
+    /////
+    Cut_NodeWriteCutsNew( p, Node, pList );
+    // filter the cuts
+//clk = clock();
+//    if ( p->pParams->fFilter )
+//        Cut_CutFilter( p, pList0 );
+//p->timeFilter += clock() - clk;
+    // perform mapping of this node with these cuts
+clk = clock();
+    if ( p->pParams->fMap && !p->pParams->fSeq )
+    {
+//        int Delay1, Delay2;
+//        Delay1 = Cut_NodeMapping( p, pList, Node, Node0, Node1 );    
+//        Delay2 = Cut_NodeMapping2( p, pList, Node, Node0, Node1 );   
+//        assert( Delay1 >= Delay2 );
+        Cut_NodeMapping( p, pList, Node, Node0, Node1 );
+    }
+p->timeMap += clock() - clk;
+    return pList;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns optimum delay mapping.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_NodeMapping2( Cut_Man_t * p, Cut_Cut_t * pCuts, int Node, int Node0, int Node1 )
+{
+    Cut_Cut_t * pCut;
+    int DelayMin, DelayCur, i;
+    if ( pCuts == NULL )
+        p->nDelayMin = -1;
+    if ( p->nDelayMin == -1 )
+        return -1;
+    DelayMin = 1000000;
+    Cut_ListForEachCut( pCuts, pCut )
+    {
+        if ( pCut->nLeaves == 1 )
+            continue;
+        DelayCur = 0;
+        for ( i = 0; i < (int)pCut->nLeaves; i++ )
+            if ( DelayCur < Vec_IntEntry(p->vDelays, pCut->pLeaves[i]) )
+                DelayCur = Vec_IntEntry(p->vDelays, pCut->pLeaves[i]);
+        if ( DelayMin > DelayCur )
+            DelayMin = DelayCur;
+    }
+    if ( DelayMin == 1000000 )
+    {
+         p->nDelayMin = -1;
+         return -1;
+    }
+    DelayMin++;
+    Vec_IntWriteEntry( p->vDelays, Node, DelayMin );
+    if ( p->nDelayMin < DelayMin )
+        p->nDelayMin = DelayMin;
+    return DelayMin;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns optimum delay mapping using the largest cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_NodeMapping( Cut_Man_t * p, Cut_Cut_t * pCuts, int Node, int Node0, int Node1 )
+{
+    Cut_Cut_t * pCut0, * pCut1, * pCut;
+    int Delay0, Delay1, Delay;
+    // get the fanin cuts
+    Delay0 = Vec_IntEntry( p->vDelays2, Node0 );
+    Delay1 = Vec_IntEntry( p->vDelays2, Node1 );
+    pCut0 = (Delay0 == 0) ? Vec_PtrEntry( p->vCutsNew, Node0 ) : Vec_PtrEntry( p->vCutsMax, Node0 );
+    pCut1 = (Delay1 == 0) ? Vec_PtrEntry( p->vCutsNew, Node1 ) : Vec_PtrEntry( p->vCutsMax, Node1 );
+    if ( Delay0 == Delay1 )
+        Delay = (Delay0 == 0) ? Delay0 + 1: Delay0;
+    else if ( Delay0 > Delay1 )
+    {
+        Delay = Delay0;
+        pCut1 = Vec_PtrEntry( p->vCutsNew, Node1 );
+        assert( pCut1->nLeaves == 1 );
+    }
+    else // if ( Delay0 < Delay1 )
+    {
+        Delay = Delay1;
+        pCut0 = Vec_PtrEntry( p->vCutsNew, Node0 );
+        assert( pCut0->nLeaves == 1 );
+    }
+    // merge the cuts
+    if ( pCut0->nLeaves < pCut1->nLeaves )
+        pCut  = Cut_CutMergeTwo( p, pCut1, pCut0 );
+    else
+        pCut  = Cut_CutMergeTwo( p, pCut0, pCut1 );
+    if ( pCut == NULL )
+    {
+        Delay++;
+        pCut = Cut_CutAlloc( p );
+        pCut->nLeaves = 2;
+        pCut->pLeaves[0] = Node0 < Node1 ? Node0 : Node1;
+        pCut->pLeaves[1] = Node0 < Node1 ? Node1 : Node0;
+    }
+    assert( Delay > 0 );
+    Vec_IntWriteEntry( p->vDelays2, Node, Delay );
+    Vec_PtrWriteEntry( p->vCutsMax, Node, pCut );
+    if ( p->nDelayMin < Delay )
+        p->nDelayMin = Delay;
+    return Delay;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes area after mapping.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_ManMappingArea_rec( Cut_Man_t * p, int Node )
+{
+    Cut_Cut_t * pCut;
+    int i, Counter;
+    if ( p->vCutsMax == NULL )
+        return 0;
+    pCut = Vec_PtrEntry( p->vCutsMax, Node );
+    if ( pCut == NULL || pCut->nLeaves == 1 )
+        return 0;
+    Counter = 0;
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+        Counter += Cut_ManMappingArea_rec( p, pCut->pLeaves[i] );
+    Vec_PtrWriteEntry( p->vCutsMax, Node, NULL );
+    return 1 + Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts by merging cuts at two nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeDoComputeCuts( Cut_Man_t * p, Cut_List_t * pSuper, int Node, int fCompl0, int fCompl1, Cut_Cut_t * pList0, Cut_Cut_t * pList1, int fTriv, int TreeCode )
+{
+    Cut_Cut_t * pStop0, * pStop1, * pTemp0, * pTemp1, * pStore0, * pStore1;
+    int i, nCutsOld, Limit;
+    // start with the elementary cut
+    if ( fTriv ) 
+    {
+//        printf( "Creating trivial cut %d.\n", Node );
+        pTemp0 = Cut_CutCreateTriv( p, Node );
+        Cut_ListAdd( pSuper, pTemp0 );
+        p->nNodeCuts++;
+    }
+    // get the cut lists of children
+    if ( pList0 == NULL || pList1 == NULL || (p->pParams->fLocal && TreeCode)  )
+        return;
+
+    // remember the old number of cuts
+    nCutsOld = p->nCutsCur;
+    Limit = p->pParams->nVarsMax;
+    // get the simultation bit of the node
+    p->fSimul = (fCompl0 ^ pList0->fSimul) & (fCompl1 ^ pList1->fSimul);
+    // set temporary variables
+    p->fCompl0 = fCompl0;
+    p->fCompl1 = fCompl1;
+    // if tree cuts are computed, make sure only the unit cuts propagate over the DAG nodes
+    if ( TreeCode & 1 )
+    {
+        assert( pList0->nLeaves == 1 );
+        pStore0 = pList0->pNext;
+        pList0->pNext = NULL;
+    }
+    if ( TreeCode & 2 )
+    {
+        assert( pList1->nLeaves == 1 );
+        pStore1 = pList1->pNext;
+        pList1->pNext = NULL;
+    }
+    // find the point in the list where the max-var cuts begin
+    Cut_ListForEachCut( pList0, pStop0 )
+        if ( pStop0->nLeaves == (unsigned)Limit )
+            break;
+    Cut_ListForEachCut( pList1, pStop1 )
+        if ( pStop1->nLeaves == (unsigned)Limit )
+            break;
+
+    // small by small
+    Cut_ListForEachCutStop( pList0, pTemp0, pStop0 )
+    Cut_ListForEachCutStop( pList1, pTemp1, pStop1 )
+    {
+        if ( Cut_CutProcessTwo( p, pTemp0, pTemp1, pSuper ) )
+            goto Quits;
+    }
+    // small by large
+    Cut_ListForEachCutStop( pList0, pTemp0, pStop0 )
+    Cut_ListForEachCut( pStop1, pTemp1 )
+    {
+        if ( (pTemp0->uSign & pTemp1->uSign) != pTemp0->uSign )
+            continue;
+        if ( Cut_CutProcessTwo( p, pTemp0, pTemp1, pSuper ) )
+            goto Quits;
+    }
+    // small by large
+    Cut_ListForEachCutStop( pList1, pTemp1, pStop1 )
+    Cut_ListForEachCut( pStop0, pTemp0 )
+    {
+        if ( (pTemp0->uSign & pTemp1->uSign) != pTemp1->uSign )
+            continue;
+        if ( Cut_CutProcessTwo( p, pTemp0, pTemp1, pSuper ) )
+            goto Quits;
+    }
+    // large by large
+    Cut_ListForEachCut( pStop0, pTemp0 )
+    Cut_ListForEachCut( pStop1, pTemp1 )
+    {
+        assert( pTemp0->nLeaves == (unsigned)Limit && pTemp1->nLeaves == (unsigned)Limit );
+        if ( pTemp0->uSign != pTemp1->uSign )
+            continue;
+        for ( i = 0; i < Limit; i++ )
+            if ( pTemp0->pLeaves[i] != pTemp1->pLeaves[i] )
+                break;
+        if ( i < Limit )
+            continue;
+        if ( Cut_CutProcessTwo( p, pTemp0, pTemp1, pSuper ) )
+            goto Quits;
+    } 
+    if ( p->nNodeCuts == 0 )
+        p->nNodesNoCuts++;
+Quits:
+    if ( TreeCode & 1 )
+        pList0->pNext = pStore0;
+    if ( TreeCode & 2 )
+        pList1->pNext = pStore1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts by unioning cuts at a choice node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_NodeUnionCuts( Cut_Man_t * p, Vec_Int_t * vNodes )
+{
+    Cut_List_t Super, * pSuper = &Super;
+    Cut_Cut_t * pList, * pListStart, * pCut, * pCut2, * pTop;
+    int i, k, Node, Root, Limit = p->pParams->nVarsMax;
+    int clk = clock();
+
+    // start the new list
+    Cut_ListStart( pSuper );
+
+    // remember the root node to save the resulting cuts
+    Root = Vec_IntEntry( vNodes, 0 );
+    p->nNodeCuts = 1;
+
+    // collect small cuts first
+    Vec_PtrClear( p->vTemp );
+    Vec_IntForEachEntry( vNodes, Node, i )
+    {
+        // get the cuts of this node
+        pList = Cut_NodeReadCutsNew( p, Node );
+        Cut_NodeWriteCutsNew( p, Node, NULL );
+        assert( pList );
+        // remember the starting point
+        pListStart = pList->pNext;
+        pList->pNext = NULL;
+        // save or recycle the elementary cut
+        if ( i == 0 )
+            Cut_ListAdd( pSuper, pList ), pTop = pList;
+        else
+            Cut_CutRecycle( p, pList );
+        // save all the cuts that are smaller than the limit
+        Cut_ListForEachCutSafe( pListStart, pCut, pCut2 )
+        {
+            if ( pCut->nLeaves == (unsigned)Limit )
+            {
+                Vec_PtrPush( p->vTemp, pCut );
+                break;
+            }
+            // check containment
+            if ( p->pParams->fFilter && Cut_CutFilterOne( p, pSuper, pCut ) )
+                continue;
+            // set the complemented bit by comparing the first cut with the current cut
+            pCut->fCompl = pTop->fSimul ^ pCut->fSimul;
+            pListStart = pCut->pNext;
+            pCut->pNext = NULL;
+            // add to the list
+            Cut_ListAdd( pSuper, pCut );
+            if ( ++p->nNodeCuts == p->pParams->nKeepMax )
+            {
+                // recycle the rest of the cuts of this node
+                Cut_ListForEachCutSafe( pListStart, pCut, pCut2 )
+                    Cut_CutRecycle( p, pCut );
+                // recycle all cuts of other nodes
+                Vec_IntForEachEntryStart( vNodes, Node, k, i+1 )
+                    Cut_NodeFreeCuts( p, Node );
+                // recycle the saved cuts of other nodes
+                Vec_PtrForEachEntry( p->vTemp, pList, k )
+                    Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+                        Cut_CutRecycle( p, pCut );
+                goto finish;
+            }
+        }
+    } 
+    // collect larger cuts next
+    Vec_PtrForEachEntry( p->vTemp, pList, i )
+    {
+        Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+        {
+            // check containment
+            if ( p->pParams->fFilter && Cut_CutFilterOne( p, pSuper, pCut ) )
+                continue;
+            // set the complemented bit
+            pCut->fCompl = pTop->fSimul ^ pCut->fSimul;
+            pListStart = pCut->pNext;
+            pCut->pNext = NULL;
+            // add to the list
+            Cut_ListAdd( pSuper, pCut );
+            if ( ++p->nNodeCuts == p->pParams->nKeepMax )
+            {
+                // recycle the rest of the cuts
+                Cut_ListForEachCutSafe( pListStart, pCut, pCut2 )
+                    Cut_CutRecycle( p, pCut );
+                // recycle the saved cuts of other nodes
+                Vec_PtrForEachEntryStart( p->vTemp, pList, k, i+1 )
+                    Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+                        Cut_CutRecycle( p, pCut );
+                goto finish;
+            }
+        }
+    }
+finish :
+    // set the cuts at the node
+    assert( Cut_NodeReadCutsNew(p, Root) == NULL );
+    pList = Cut_ListFinish( pSuper );
+    Cut_NodeWriteCutsNew( p, Root, pList );
+p->timeUnion += clock() - clk;
+    // filter the cuts
+//clk = clock();
+//    if ( p->pParams->fFilter )
+//        Cut_CutFilter( p, pList );
+//p->timeFilter += clock() - clk;
+    p->nNodes -= vNodes->nSize - 1;
+    return pList;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the cuts by unioning cuts at a choice node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_NodeUnionCutsSeq( Cut_Man_t * p, Vec_Int_t * vNodes, int CutSetNum, int fFirst )
+{
+    Cut_List_t Super, * pSuper = &Super;
+    Cut_Cut_t * pList, * pListStart, * pCut, * pCut2, * pTop;
+    int i, k, Node, Root, Limit = p->pParams->nVarsMax;
+    int clk = clock();
+
+    // start the new list
+    Cut_ListStart( pSuper );
+
+    // remember the root node to save the resulting cuts
+    Root = Vec_IntEntry( vNodes, 0 );
+    p->nNodeCuts = 1;
+
+    // store the original lists for comparison
+    p->pCompareOld = Cut_NodeReadCutsOld( p, Root );
+    p->pCompareNew = (CutSetNum >= 0)? Cut_NodeReadCutsNew( p, Root ) : NULL;
+
+    // get the topmost cut
+    pTop = NULL;
+    if ( (pTop = Cut_NodeReadCutsOld( p, Root )) == NULL )
+        pTop = Cut_NodeReadCutsNew( p, Root );
+    assert( pTop != NULL );
+
+    // collect small cuts first
+    Vec_PtrClear( p->vTemp );
+    Vec_IntForEachEntry( vNodes, Node, i )
+    {
+        // get the cuts of this node
+        if ( i == 0 && CutSetNum >= 0 )
+        {
+            pList = Cut_NodeReadCutsTemp( p, CutSetNum );
+            Cut_NodeWriteCutsTemp( p, CutSetNum, NULL );
+        }
+        else
+        {
+            pList = Cut_NodeReadCutsNew( p, Node );
+            Cut_NodeWriteCutsNew( p, Node, NULL );
+        }
+        if ( pList == NULL )
+            continue;
+
+        // process the cuts
+        if ( fFirst )
+        {
+            // remember the starting point
+            pListStart = pList->pNext;
+            pList->pNext = NULL;
+            // save or recycle the elementary cut
+            if ( i == 0 )
+                Cut_ListAdd( pSuper, pList );
+            else
+                Cut_CutRecycle( p, pList );
+        }
+        else
+            pListStart = pList;
+
+        // save all the cuts that are smaller than the limit
+        Cut_ListForEachCutSafe( pListStart, pCut, pCut2 )
+        {
+            if ( pCut->nLeaves == (unsigned)Limit )
+            {
+                Vec_PtrPush( p->vTemp, pCut );
+                break;
+            }
+            // check containment
+//            if ( p->pParams->fFilter && Cut_CutFilterOne( p, pSuper, pCut ) )
+//                continue;
+            if ( p->pParams->fFilter )
+            {
+                if ( Cut_CutFilterOne(p, pSuper, pCut) )
+                    continue;
+                if ( p->pParams->fSeq )
+                {
+                    if ( p->pCompareOld && Cut_CutFilterOld(p, p->pCompareOld, pCut) )
+                        continue;
+                    if ( p->pCompareNew && Cut_CutFilterOld(p, p->pCompareNew, pCut) )
+                        continue;
+                }
+            }
+
+            // set the complemented bit by comparing the first cut with the current cut
+            pCut->fCompl = pTop->fSimul ^ pCut->fSimul;
+            pListStart = pCut->pNext;
+            pCut->pNext = NULL;
+            // add to the list
+            Cut_ListAdd( pSuper, pCut );
+            if ( ++p->nNodeCuts == p->pParams->nKeepMax )
+            {
+                // recycle the rest of the cuts of this node
+                Cut_ListForEachCutSafe( pListStart, pCut, pCut2 )
+                    Cut_CutRecycle( p, pCut );
+                // recycle all cuts of other nodes
+                Vec_IntForEachEntryStart( vNodes, Node, k, i+1 )
+                    Cut_NodeFreeCuts( p, Node );
+                // recycle the saved cuts of other nodes
+                Vec_PtrForEachEntry( p->vTemp, pList, k )
+                    Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+                        Cut_CutRecycle( p, pCut );
+                goto finish;
+            }
+        }
+    } 
+    // collect larger cuts next
+    Vec_PtrForEachEntry( p->vTemp, pList, i )
+    {
+        Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+        {
+            // check containment
+//            if ( p->pParams->fFilter && Cut_CutFilterOne( p, pSuper, pCut ) )
+//                continue;
+            if ( p->pParams->fFilter )
+            {
+                if ( Cut_CutFilterOne(p, pSuper, pCut) )
+                    continue;
+                if ( p->pParams->fSeq )
+                {
+                    if ( p->pCompareOld && Cut_CutFilterOld(p, p->pCompareOld, pCut) )
+                        continue;
+                    if ( p->pCompareNew && Cut_CutFilterOld(p, p->pCompareNew, pCut) )
+                        continue;
+                }
+            }
+
+            // set the complemented bit
+            pCut->fCompl = pTop->fSimul ^ pCut->fSimul;
+            pListStart   = pCut->pNext;
+            pCut->pNext  = NULL;
+            // add to the list
+            Cut_ListAdd( pSuper, pCut );
+            if ( ++p->nNodeCuts == p->pParams->nKeepMax )
+            {
+                // recycle the rest of the cuts
+                Cut_ListForEachCutSafe( pListStart, pCut, pCut2 )
+                    Cut_CutRecycle( p, pCut );
+                // recycle the saved cuts of other nodes
+                Vec_PtrForEachEntryStart( p->vTemp, pList, k, i+1 )
+                    Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+                        Cut_CutRecycle( p, pCut );
+                goto finish;
+            }
+        }
+    }
+finish :
+    // set the cuts at the node
+    pList = Cut_ListFinish( pSuper );
+
+    // set the lists at the node
+//    assert( Cut_NodeReadCutsNew(p, Root) == NULL );
+//    Cut_NodeWriteCutsNew( p, Root, pList );
+    if ( CutSetNum >= 0 )
+    {
+        assert( Cut_NodeReadCutsTemp(p, CutSetNum) == NULL );
+        Cut_NodeWriteCutsTemp( p, CutSetNum, pList );
+    }
+    else
+    {
+        assert( Cut_NodeReadCutsNew(p, Root) == NULL );
+        Cut_NodeWriteCutsNew( p, Root, pList );
+    }
+
+p->timeUnion += clock() - clk;
+    // filter the cuts
+//clk = clock();
+//    if ( p->pParams->fFilter )
+//        Cut_CutFilter( p, pList );
+//p->timeFilter += clock() - clk;
+//    if ( fFirst )
+//        p->nNodes -= vNodes->nSize - 1;
+    return pList;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies that the list contains only non-dominated cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_CutListVerify( Cut_Cut_t * pList )
+{ 
+    Cut_Cut_t * pCut, * pDom;
+    Cut_ListForEachCut( pList, pCut )
+    {
+        Cut_ListForEachCutStop( pList, pDom, pCut )
+        {
+            if ( Cut_CutCheckDominance( pDom, pCut ) )
+            {
+                int x = 0;
+                printf( "******************* These are contained cuts:\n" );
+                Cut_CutPrint( pDom, 1 );
+                Cut_CutPrint( pDom, 1 );
+                
+                return 0;
+            }
+        }
+    }
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutOracle.c b/src/opt/cut/cutOracle.c
new file mode 100644
index 00000000..3eb4462b
--- /dev/null
+++ b/src/opt/cut/cutOracle.c
@@ -0,0 +1,428 @@
+/**CFile****************************************************************
+
+  FileName    [cutOracle.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Procedures to compute cuts for a node using the oracle.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutOracle.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+struct Cut_OracleStruct_t_
+{
+    // cut comptupatation parameters
+    Cut_Params_t *     pParams;
+    Vec_Int_t *        vFanCounts;
+    int                fSimul;
+    // storage for cuts
+    Vec_Ptr_t *        vCutsNew;
+    Vec_Ptr_t *        vCuts0;
+    Vec_Ptr_t *        vCuts1;
+    // oracle info 
+    Vec_Int_t *        vNodeCuts;
+    Vec_Int_t *        vNodeStarts;
+    Vec_Int_t *        vCutPairs;
+    // memory management
+    Extra_MmFixed_t *  pMmCuts;
+    int                EntrySize;
+    int                nTruthWords;
+    // stats
+    int                timeTotal;
+    int                nCuts;
+    int                nCutsTriv;
+};
+
+static Cut_Cut_t * Cut_CutStart( Cut_Oracle_t * p );
+static Cut_Cut_t * Cut_CutTriv( Cut_Oracle_t * p, int Node );
+static Cut_Cut_t * Cut_CutMerge( Cut_Oracle_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the cut oracle.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Oracle_t * Cut_OracleStart( Cut_Man_t * pMan )
+{
+    Cut_Oracle_t * p;
+    int clk = clock();
+
+    assert( pMan->pParams->nVarsMax >= 3 && pMan->pParams->nVarsMax <= CUT_SIZE_MAX );
+    assert( pMan->pParams->fRecord );
+
+    p = ALLOC( Cut_Oracle_t, 1 );
+    memset( p, 0, sizeof(Cut_Oracle_t) );
+
+    // set and correct parameters
+    p->pParams     = pMan->pParams;
+
+    // transfer the recording info
+    p->vNodeCuts   = pMan->vNodeCuts;    pMan->vNodeCuts   = NULL;
+    p->vNodeStarts = pMan->vNodeStarts;  pMan->vNodeStarts = NULL;
+    p->vCutPairs   = pMan->vCutPairs;    pMan->vCutPairs   = NULL;
+
+    // prepare storage for cuts
+    p->vCutsNew = Vec_PtrAlloc( p->pParams->nIdsMax );
+    Vec_PtrFill( p->vCutsNew, p->pParams->nIdsMax, NULL );
+    p->vCuts0 = Vec_PtrAlloc( 100 );
+    p->vCuts1 = Vec_PtrAlloc( 100 );
+
+    // entry size
+    p->EntrySize = sizeof(Cut_Cut_t) + p->pParams->nVarsMax * sizeof(int);
+    if ( p->pParams->fTruth )
+    {
+        if ( p->pParams->nVarsMax > 8 )
+        {
+            p->pParams->fTruth = 0;
+            printf( "Skipping computation of truth table for more than 8 inputs.\n" );
+        }
+        else
+        {
+            p->nTruthWords = Cut_TruthWords( p->pParams->nVarsMax );
+            p->EntrySize += p->nTruthWords * sizeof(unsigned);
+        }
+    }
+    // memory for cuts
+    p->pMmCuts = Extra_MmFixedStart( p->EntrySize );
+    return p;
+}
+/**Function*************************************************************
+
+  Synopsis    [Stop the cut oracle.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_OracleStop( Cut_Oracle_t * p )
+{
+    Cut_Cut_t * pCut;
+    int i;
+
+//    if ( p->pParams->fVerbose )
+    {
+        printf( "Cut computation statistics with oracle:\n" );
+        printf( "Current cuts      = %8d. (Trivial = %d.)\n", p->nCuts-p->nCutsTriv, p->nCutsTriv );
+        PRT( "Total time ", p->timeTotal );
+    }
+
+    Vec_PtrForEachEntry( p->vCutsNew, pCut, i )
+        if ( pCut != NULL )
+        {
+            int k = 0;
+        }
+    if ( p->vCuts0 )      Vec_PtrFree( p->vCuts0 );
+    if ( p->vCuts1 )      Vec_PtrFree( p->vCuts1 );
+    if ( p->vCutsNew )    Vec_PtrFree( p->vCutsNew );
+    if ( p->vFanCounts )  Vec_IntFree( p->vFanCounts );
+
+    if ( p->vNodeCuts )   Vec_IntFree( p->vNodeCuts );
+    if ( p->vNodeStarts ) Vec_IntFree( p->vNodeStarts );
+    if ( p->vCutPairs )   Vec_IntFree( p->vCutPairs );
+
+    Extra_MmFixedStop( p->pMmCuts );
+    free( p ); 
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_OracleSetFanoutCounts( Cut_Oracle_t * p, Vec_Int_t * vFanCounts )
+{
+    p->vFanCounts = vFanCounts;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_OracleReadDrop( Cut_Oracle_t * p )
+{
+    return p->pParams->fDrop;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the trivial cut for the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_OracleNodeSetTriv( Cut_Oracle_t * p, int Node )
+{
+    assert( Vec_PtrEntry( p->vCutsNew, Node ) == NULL );
+    Vec_PtrWriteEntry( p->vCutsNew, Node, Cut_CutTriv(p, Node) );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutStart( Cut_Oracle_t * p )
+{
+    Cut_Cut_t * pCut;
+    // cut allocation
+    pCut = (Cut_Cut_t *)Extra_MmFixedEntryFetch( p->pMmCuts );
+    memset( pCut, 0, sizeof(Cut_Cut_t) );
+    pCut->nVarsMax   = p->pParams->nVarsMax;
+    pCut->fSimul     = p->fSimul;
+    p->nCuts++;
+    return pCut;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the trivial cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutTriv( Cut_Oracle_t * p, int Node )
+{
+    Cut_Cut_t * pCut;
+    pCut = Cut_CutStart( p );
+    pCut->nLeaves    = 1;
+    pCut->pLeaves[0] = Node;
+    if ( p->pParams->fTruth )
+    {
+        unsigned * pTruth = Cut_CutReadTruth(pCut);
+        int i;
+        for ( i = 0; i < p->nTruthWords; i++ )
+            pTruth[i] = 0xAAAAAAAA;
+    }
+    p->nCutsTriv++;
+    return pCut;
+} 
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_CutMerge( Cut_Oracle_t * p, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1 )
+{
+    Cut_Cut_t * pCut;
+    int Limit, i, k, c;
+    // create the leaves of the new cut
+    pCut = Cut_CutStart( p );
+    Limit = p->pParams->nVarsMax;
+    for ( i = k = c = 0; c < Limit; c++ )
+    {
+        if ( k == (int)pCut1->nLeaves )
+        {
+            if ( i == (int)pCut0->nLeaves )
+            {
+                pCut->nLeaves = c;
+                return pCut;
+            }
+            pCut->pLeaves[c] = pCut0->pLeaves[i++];
+            continue;
+        }
+        if ( i == (int)pCut0->nLeaves )
+        {
+            if ( k == (int)pCut1->nLeaves )
+            {
+                pCut->nLeaves = c;
+                return pCut;
+            }
+            pCut->pLeaves[c] = pCut1->pLeaves[k++];
+            continue;
+        }
+        if ( pCut0->pLeaves[i] < pCut1->pLeaves[k] )
+        {
+            pCut->pLeaves[c] = pCut0->pLeaves[i++];
+            continue;
+        }
+        if ( pCut0->pLeaves[i] > pCut1->pLeaves[k] )
+        {
+            pCut->pLeaves[c] = pCut1->pLeaves[k++];
+            continue;
+        }
+        pCut->pLeaves[c] = pCut0->pLeaves[i++]; 
+        k++;
+    }
+    assert( i == (int)pCut0->nLeaves && k == (int)pCut1->nLeaves );
+    pCut->nLeaves = c;
+    return pCut;
+} 
+
+/**Function*************************************************************
+
+  Synopsis    [Reconstruct the cuts of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_Cut_t * Cut_OracleComputeCuts( Cut_Oracle_t * p, int Node, int Node0, int Node1, int fCompl0, int fCompl1 )
+{
+    Cut_Cut_t * pList = NULL, ** ppTail = &pList;
+    Cut_Cut_t * pCut, * pCut0, * pCut1, * pList0, * pList1;
+    int iCutStart, nCuts, i, Entry;
+    int clk = clock();
+
+    // get the cuts of the children
+    pList0 = Vec_PtrEntry( p->vCutsNew, Node0 );
+    pList1 = Vec_PtrEntry( p->vCutsNew, Node1 );
+    assert( pList0 && pList1 );
+
+    // get the complemented attribute of the cut
+    p->fSimul = (fCompl0 ^ pList0->fSimul) & (fCompl1 ^ pList1->fSimul);
+
+    // collect the cuts
+    Vec_PtrClear( p->vCuts0 );
+    Cut_ListForEachCut( pList0, pCut )
+        Vec_PtrPush( p->vCuts0, pCut );
+    Vec_PtrClear( p->vCuts1 );
+    Cut_ListForEachCut( pList1, pCut )
+        Vec_PtrPush( p->vCuts1, pCut );
+
+    // get the first and last cuts of this node
+    nCuts = Vec_IntEntry(p->vNodeCuts, Node);
+    iCutStart = Vec_IntEntry(p->vNodeStarts, Node);
+
+    // create trivial cut
+    assert( Vec_IntEntry(p->vCutPairs, iCutStart) == 0 );
+    pCut = Cut_CutTriv( p, Node );
+    *ppTail = pCut;
+    ppTail = &pCut->pNext;
+    // create other cuts
+    for ( i = 1; i < nCuts; i++ )
+    {
+        Entry = Vec_IntEntry( p->vCutPairs, iCutStart + i );
+        pCut0 = Vec_PtrEntry( p->vCuts0, Entry & 0xFFFF );
+        pCut1 = Vec_PtrEntry( p->vCuts1, Entry >> 16 );
+        pCut  = Cut_CutMerge( p, pCut0, pCut1 );
+        *ppTail = pCut;
+        ppTail = &pCut->pNext;
+        // compute the truth table
+        if ( p->pParams->fTruth )
+            Cut_TruthComputeOld( pCut, pCut0, pCut1, fCompl0, fCompl1 );
+    }
+    *ppTail = NULL;
+
+    // write the new cut
+    assert( Vec_PtrEntry( p->vCutsNew, Node ) == NULL );
+    Vec_PtrWriteEntry( p->vCutsNew, Node, pList );
+p->timeTotal += clock() - clk;
+    return pList;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deallocates the cuts at the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_OracleFreeCuts( Cut_Oracle_t * p, int Node )
+{
+    Cut_Cut_t * pList, * pCut, * pCut2;
+    pList = Vec_PtrEntry( p->vCutsNew, Node );
+    if ( pList == NULL )
+        return;
+    Cut_ListForEachCutSafe( pList, pCut, pCut2 )
+        Extra_MmFixedEntryRecycle( p->pMmCuts, (char *)pCut );
+    Vec_PtrWriteEntry( p->vCutsNew, Node, pList );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Consider dropping cuts if they are useless by now.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_OracleTryDroppingCuts( Cut_Oracle_t * p, int Node )
+{
+    int nFanouts;
+    assert( p->vFanCounts );
+    nFanouts = Vec_IntEntry( p->vFanCounts, Node );
+    assert( nFanouts > 0 );
+    if ( --nFanouts == 0 )
+        Cut_OracleFreeCuts( p, Node );
+    Vec_IntWriteEntry( p->vFanCounts, Node, nFanouts );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutPre22.c b/src/opt/cut/cutPre22.c
new file mode 100644
index 00000000..5cb87a9c
--- /dev/null
+++ b/src/opt/cut/cutPre22.c
@@ -0,0 +1,988 @@
+/**CFile****************************************************************
+
+  FileName    [cutPre22.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Precomputes truth tables for the 2x2 macro cell.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutPre22.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define CUT_CELL_MVAR  9
+
+typedef struct Cut_Cell_t_ Cut_Cell_t;
+typedef struct Cut_CMan_t_ Cut_CMan_t;
+
+struct Cut_Cell_t_
+{
+    Cut_Cell_t *       pNext;                        // pointer to the next cell in the table
+    Cut_Cell_t *       pNextVar;                     // pointer to the next cell of this support size
+    Cut_Cell_t *       pParent;                      // pointer to the cell used to derive this one
+    int                nUsed;                        // the number of times the cell is used
+    char               Box[4];                       // functions in the boxes
+    unsigned           nVars          :  4;          // the number of variables
+    unsigned           CrossBar0      :  4;          // the variable set equal
+    unsigned           CrossBar1      :  4;          // the variable set equal
+    unsigned           CrossBarPhase  :  2;          // the phase of the cross bar (0, 1, or 2)
+    unsigned           CanonPhase     : 18;          // the canonical phase
+    char               CanonPerm[CUT_CELL_MVAR+3];   // semicanonical permutation
+    short              Store[2*CUT_CELL_MVAR];       // minterm counts in the cofactors
+    unsigned           uTruth[1<<(CUT_CELL_MVAR-5)]; // the current truth table
+};
+
+struct Cut_CMan_t_
+{
+    // storage for canonical cells
+    Extra_MmFixed_t *  pMem;
+    st_table *         tTable;
+    Cut_Cell_t *       pSameVar[CUT_CELL_MVAR+1];
+    // elementary truth tables
+    unsigned           uInputs[CUT_CELL_MVAR][1<<(CUT_CELL_MVAR-5)];
+    // temporary truth tables
+    unsigned           uTemp1[22][1<<(CUT_CELL_MVAR-5)];
+    unsigned           uTemp2[22][1<<(CUT_CELL_MVAR-5)];
+    unsigned           uTemp3[22][1<<(CUT_CELL_MVAR-5)];
+    unsigned           uFinal[1<<(CUT_CELL_MVAR-5)];
+    unsigned           puAux[1<<(CUT_CELL_MVAR-5)];
+    // statistical variables
+    int                nTotal;
+    int                nGood;
+    int                nVarCounts[CUT_CELL_MVAR+1];
+    int                nSymGroups[CUT_CELL_MVAR+1];
+    int                nSymGroupsE[CUT_CELL_MVAR+1];
+    int                timeCanon;
+    int                timeSupp;
+    int                timeTable;
+    int                nCellFound;
+    int                nCellNotFound;
+};
+
+// NP-classes of functions of 3 variables (22)
+static char * s_NP3[22] = {
+    " 0\n",                          // 00    const 0            // 0 vars 
+    " 1\n",                          // 01    const 1            // 0 vars  
+    "1 1\n",                         // 02    a                  // 1 vars  
+    "11 1\n",                        // 03    ab                 // 2 vars  
+    "11 0\n",                        // 04    (ab)'              // 2 vars  
+    "10 1\n01 1\n",                  // 05    a<+>b              // 2 vars  
+    "111 1\n",                       // 06 0s abc                // 3 vars  
+    "111 0\n",                       // 07    (abc)'             // 
+    "11- 1\n1-1 1\n",                // 08 1p a(b+c)             // 
+    "11- 0\n1-1 0\n",                // 09    (a(b+c))'          // 
+    "111 1\n100 1\n010 1\n001 1\n",  // 10 2s a<+>b<+>c          // 
+    "10- 0\n1-0 0\n011 0\n",         // 11 3p a<+>bc             // 
+    "101 1\n110 1\n",                // 12 4p a(b<+>c)           // 
+    "101 0\n110 0\n",                // 13    (a(b<+>c))'        // 
+    "11- 1\n1-1 1\n-11 1\n",         // 14 5s ab+bc+ac           // 
+    "111 1\n000 1\n",                // 15 6s abc+a'b'c'         // 
+    "111 0\n000 0\n",                // 16    (abc+a'b'c')'      // 
+    "11- 1\n-11 1\n0-1 1\n",         // 17 7  ab+bc+a'c          // 
+    "011 1\n101 1\n110 1\n",         // 18 8s a'bc+ab'c+abc'     // 
+    "011 0\n101 0\n110 0\n",         // 19    (a'bc+ab'c+abc')'  // 
+    "100 1\n-11 1\n",                // 20 9p ab'c'+bc           // 
+    "100 0\n-11 0\n"                 // 21    (ab'c'+bc)'        // 
+};
+
+// NP-classes of functions of 3 variables (22)
+static char * s_NP3Names[22] = {
+    "   const 0            ",
+    "   const 1            ",
+    "   a                  ",
+    "   ab                 ",
+    "   (ab)'              ",
+    "   a<+>b              ",
+    "0s abc                ",
+    "   (abc)'             ",
+    "1p a(b+c)             ",
+    "   (a(b+c))'          ",
+    "2s a<+>b<+>c          ",
+    "3p a<+>bc             ",
+    "4p a(b<+>c)           ",
+    "   (a(b<+>c))'        ",
+    "5s ab+bc+ac           ",
+    "6s abc+a'b'c'         ",
+    "   (abc+a'b'c')'      ",
+    "7  ab+bc+a'c          ",
+    "8s a'bc+ab'c+abc'     ",
+    "   (a'bc+ab'c+abc')'  ",
+    "9p ab'c'+bc           ",
+    "   (ab'c'+bc)'        "
+};
+
+// the number of variables in each function
+static int s_NP3VarNums[22] = { 0, 0, 1, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 };
+
+// NPN classes of functions of exactly 3 inputs (10)
+static int s_NPNe3[10] = { 6, 8, 10, 11, 12, 14, 15, 17, 18, 20 };
+
+// NPN classes of functions of exactly 3 inputs that are symmetric (5)
+static int s_NPNe3s[10] = { 6, 10, 14, 15, 18 };
+
+// NPN classes of functions of exactly 3 inputs (4)
+static int s_NPNe3p[10] = { 8, 11, 12, 20 };
+
+static Cut_CMan_t * Cut_CManStart();
+static void Cut_CManStop( Cut_CMan_t * p );
+static void Cut_CellTruthElem( unsigned * InA, unsigned * InB, unsigned * InC, unsigned * pOut, int nVars, int Type );
+static void Cut_CellCanonicize( Cut_CMan_t * p, Cut_Cell_t * pCell );
+static int  Cut_CellTableLookup( Cut_CMan_t * p, Cut_Cell_t * pCell );
+static void Cut_CellSuppMin( Cut_Cell_t * pCell );
+static void Cut_CellCrossBar( Cut_Cell_t * pCell );
+
+
+static Cut_CMan_t * s_pCMan = NULL;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Start the precomputation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CellLoad()
+{
+    FILE * pFile;
+    char * pFileName = "cells22_daomap_iwls.txt";
+    char pString[1000];
+    Cut_CMan_t * p;
+    Cut_Cell_t * pCell;
+    int Length; //, i;
+    pFile = fopen( pFileName, "r" );
+    if ( pFile == NULL )
+    {
+        printf( "Cannot open file \"%s\".\n", pFileName );
+        return;
+    }
+   // start the manager
+    p = Cut_CManStart();
+    // load truth tables
+    while ( fgets(pString, 1000, pFile) )
+    {
+        Length = strlen(pString);
+        pString[Length--] = 0;
+        if ( Length == 0 )
+            continue;
+        // derive the cell
+        pCell = (Cut_Cell_t *)Extra_MmFixedEntryFetch( p->pMem );
+        memset( pCell, 0, sizeof(Cut_Cell_t) );
+        pCell->nVars = Extra_Base2Log(Length*4);
+        pCell->nUsed = 1;
+//        Extra_TruthCopy( pCell->uTruth, pTruth, nVars );
+        Extra_ReadHexadecimal( pCell->uTruth, pString, pCell->nVars );
+        Cut_CellSuppMin( pCell );
+/*
+        // set the elementary permutation
+        for ( i = 0; i < (int)pCell->nVars; i++ )
+            pCell->CanonPerm[i] = i;
+        // canonicize
+        pCell->CanonPhase = Extra_TruthSemiCanonicize( pCell->uTruth, p->puAux, pCell->nVars, pCell->CanonPerm, pCell->Store );
+*/
+        // add to the table
+        p->nTotal++;
+
+//        Extra_PrintHexadecimal( stdout, pCell->uTruth, pCell->nVars ); printf( "\n" );
+//        if ( p->nTotal == 500 )
+//            break;
+
+        if ( !Cut_CellTableLookup( p, pCell ) ) // new cell
+            p->nGood++;
+    }
+    printf( "Read %d cells from file \"%s\". Added %d cells to the table.\n", p->nTotal, pFileName, p->nGood );
+    fclose( pFile );
+//    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Precomputes truth tables for the 2x2 macro cell.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CellPrecompute()
+{
+    Cut_CMan_t * p;
+    Cut_Cell_t * pCell, * pTemp;
+    int i1, i2, i3, i, j, k, c, clk = clock(), clk2 = clock();
+
+    p = Cut_CManStart();
+
+    // precompute truth tables
+    for ( i = 0; i < 22; i++ )
+        Cut_CellTruthElem( p->uInputs[0], p->uInputs[1], p->uInputs[2], p->uTemp1[i], 9, i );
+    for ( i = 0; i < 22; i++ )
+        Cut_CellTruthElem( p->uInputs[3], p->uInputs[4], p->uInputs[5], p->uTemp2[i], 9, i );
+    for ( i = 0; i < 22; i++ )
+        Cut_CellTruthElem( p->uInputs[6], p->uInputs[7], p->uInputs[8], p->uTemp3[i], 9, i );
+/*
+        if ( k == 8 && ((i1 == 6 && i2 == 14 && i3 == 20) || (i1 == 20 && i2 == 6 && i3 == 14)) )
+        {
+            Extra_PrintBinary( stdout, &pCell->CanonPhase, pCell->nVars+1 ); printf( " : " );
+            for ( i = 0; i < pCell->nVars; i++ )
+                printf( "%d=%d/%d  ", pCell->CanonPerm[i], pCell->Store[2*i], pCell->Store[2*i+1] );
+            Extra_PrintHexadecimal( stdout, pCell->uTruth, pCell->nVars );
+            printf( "\n" );
+        }
+*/
+/*
+    // go through symmetric roots
+    for ( k = 0; k < 5; k++ )
+    for ( i1 =  0; i1 < 22; i1++ )
+    for ( i2 = i1; i2 < 22; i2++ )
+    for ( i3 = i2; i3 < 22; i3++ )
+    {
+        // derive the cell
+        pCell = (Cut_Cell_t *)Extra_MmFixedEntryFetch( p->pMem );
+        memset( pCell, 0, sizeof(Cut_Cell_t) );
+        pCell->nVars  = 9;
+        pCell->Box[0] = s_NPNe3s[k];
+        pCell->Box[1] = i1;
+        pCell->Box[2] = i2;
+        pCell->Box[3] = i3;
+        // fill in the truth table
+        Cut_CellTruthElem( p->uTemp1[i1], p->uTemp2[i2], p->uTemp3[i3], pCell->uTruth, 9, s_NPNe3s[k] );
+        // canonicize
+        Cut_CellCanonicize( pCell );
+
+        // add to the table
+        p->nTotal++;
+        if ( Cut_CellTableLookup( p, pCell ) ) // already exists
+            Extra_MmFixedEntryRecycle( p->pMem, (char *)pCell );
+        else
+            p->nGood++;
+    }
+
+    // go through partially symmetric roots
+    for ( k = 0; k < 4; k++ )
+    for ( i1 = 0;  i1 < 22; i1++ )
+    for ( i2 = 0;  i2 < 22; i2++ )
+    for ( i3 = i2; i3 < 22; i3++ )
+    {
+        // derive the cell
+        pCell = (Cut_Cell_t *)Extra_MmFixedEntryFetch( p->pMem );
+        memset( pCell, 0, sizeof(Cut_Cell_t) );
+        pCell->nVars  = 9;
+        pCell->Box[0] = s_NPNe3p[k];
+        pCell->Box[1] = i1;
+        pCell->Box[2] = i2;
+        pCell->Box[3] = i3;
+        // fill in the truth table
+        Cut_CellTruthElem( p->uTemp1[i1], p->uTemp2[i2], p->uTemp3[i3], pCell->uTruth, 9, s_NPNe3p[k] );
+        // canonicize
+        Cut_CellCanonicize( pCell );
+
+        // add to the table
+        p->nTotal++;
+        if ( Cut_CellTableLookup( p, pCell ) ) // already exists
+            Extra_MmFixedEntryRecycle( p->pMem, (char *)pCell );
+        else
+            p->nGood++;
+    }
+
+    // go through non-symmetric functions
+    for ( i1 = 0; i1 < 22; i1++ )
+    for ( i2 = 0; i2 < 22; i2++ )
+    for ( i3 = 0; i3 < 22; i3++ )
+    {
+        // derive the cell
+        pCell = (Cut_Cell_t *)Extra_MmFixedEntryFetch( p->pMem );
+        memset( pCell, 0, sizeof(Cut_Cell_t) );
+        pCell->nVars  = 9;
+        pCell->Box[0] = 17;
+        pCell->Box[1] = i1;
+        pCell->Box[2] = i2;
+        pCell->Box[3] = i3;
+        // fill in the truth table
+        Cut_CellTruthElem( p->uTemp1[i1], p->uTemp2[i2], p->uTemp3[i3], pCell->uTruth, 9, 17 );
+        // canonicize
+        Cut_CellCanonicize( pCell );
+
+        // add to the table
+        p->nTotal++;
+        if ( Cut_CellTableLookup( p, pCell ) ) // already exists
+            Extra_MmFixedEntryRecycle( p->pMem, (char *)pCell );
+        else
+            p->nGood++;
+    }
+*/
+
+    // go through non-symmetric functions
+    for ( k = 0; k < 10; k++ )
+    for ( i1 = 0; i1 < 22; i1++ )
+    for ( i2 = 0; i2 < 22; i2++ )
+    for ( i3 = 0; i3 < 22; i3++ )
+    {
+        // derive the cell
+        pCell = (Cut_Cell_t *)Extra_MmFixedEntryFetch( p->pMem );
+        memset( pCell, 0, sizeof(Cut_Cell_t) );
+        pCell->nVars  = 9;
+        pCell->Box[0] = s_NPNe3[k];
+        pCell->Box[1] = i1;
+        pCell->Box[2] = i2;
+        pCell->Box[3] = i3;
+        // set the elementary permutation
+        for ( i = 0; i < (int)pCell->nVars; i++ )
+            pCell->CanonPerm[i] = i;
+        // fill in the truth table
+        Cut_CellTruthElem( p->uTemp1[i1], p->uTemp2[i2], p->uTemp3[i3], pCell->uTruth, 9, s_NPNe3[k] );
+        // minimize the support
+        Cut_CellSuppMin( pCell );
+
+        // canonicize
+        pCell->CanonPhase = Extra_TruthSemiCanonicize( pCell->uTruth, p->puAux, pCell->nVars, pCell->CanonPerm, pCell->Store );
+
+        // add to the table
+        p->nTotal++;
+        if ( Cut_CellTableLookup( p, pCell ) ) // already exists
+            Extra_MmFixedEntryRecycle( p->pMem, (char *)pCell );
+        else
+        {
+            p->nGood++;
+            p->nVarCounts[pCell->nVars]++;
+
+            if ( pCell->nVars )
+            for ( i = 0; i < (int)pCell->nVars-1; i++ )
+            {
+                if ( pCell->Store[2*i] != pCell->Store[2*(i+1)] ) // i and i+1 cannot be symmetric
+                    continue;
+                // i and i+1 can be symmetric
+                // find the end of this group
+                for ( j = i+1; j < (int)pCell->nVars; j++ )
+                    if ( pCell->Store[2*i] != pCell->Store[2*j] ) 
+                        break;
+
+                if ( pCell->Store[2*i] == pCell->Store[2*i+1] )
+                    p->nSymGroupsE[j-i]++;
+                else
+                    p->nSymGroups[j-i]++;
+                i = j - 1;
+            }
+/*
+            if ( pCell->nVars == 3 )
+            {
+                Extra_PrintBinary( stdout, pCell->uTruth, 32 ); printf( "\n" );
+                for ( i = 0; i < (int)pCell->nVars; i++ )
+                    printf( "%d=%d/%d  ", pCell->CanonPerm[i], pCell->Store[2*i], pCell->Store[2*i+1] );
+                printf( "\n" );
+            }
+*/
+        }
+    }
+
+    printf( "BASIC: Total = %d. Good = %d. Entry = %d. ", p->nTotal, p->nGood, sizeof(Cut_Cell_t) );
+    PRT( "Time", clock() - clk );
+    printf( "Cells:  " );
+    for ( i = 0; i <= 9; i++ )
+        printf( "%d=%d ", i, p->nVarCounts[i] );
+    printf( "\nDiffs:  " );
+    for ( i = 0; i <= 9; i++ )
+        printf( "%d=%d ", i, p->nSymGroups[i] );
+    printf( "\nEquals: " );
+    for ( i = 0; i <= 9; i++ )
+        printf( "%d=%d ", i, p->nSymGroupsE[i] );
+    printf( "\n" );
+
+    // continue adding new cells using support
+    for ( k = CUT_CELL_MVAR; k > 3; k-- )
+    {
+        for ( pTemp = p->pSameVar[k]; pTemp; pTemp = pTemp->pNextVar )
+        for ( i1 = 0; i1 < k; i1++ )
+        for ( i2 = i1+1; i2 < k; i2++ )
+        for ( c = 0; c < 3; c++ )
+        {
+            // derive the cell
+            pCell = (Cut_Cell_t *)Extra_MmFixedEntryFetch( p->pMem );
+            memset( pCell, 0, sizeof(Cut_Cell_t) );
+            pCell->nVars   = pTemp->nVars;
+            pCell->pParent = pTemp;
+            // set the elementary permutation
+            for ( i = 0; i < (int)pCell->nVars; i++ )
+                pCell->CanonPerm[i] = i;
+            // fill in the truth table
+            Extra_TruthCopy( pCell->uTruth, pTemp->uTruth, pTemp->nVars );
+            // create the cross-bar
+            pCell->CrossBar0 = i1;
+            pCell->CrossBar1 = i2;
+            pCell->CrossBarPhase = c;
+            Cut_CellCrossBar( pCell );
+            // minimize the support
+//clk2 = clock();
+            Cut_CellSuppMin( pCell );
+//p->timeSupp += clock() - clk2;
+            // canonicize
+//clk2 = clock();
+            pCell->CanonPhase = Extra_TruthSemiCanonicize( pCell->uTruth, p->puAux, pCell->nVars, pCell->CanonPerm, pCell->Store );
+//p->timeCanon += clock() - clk2;
+
+            // add to the table
+//clk2 = clock();
+            p->nTotal++;
+            if ( Cut_CellTableLookup( p, pCell ) ) // already exists
+                Extra_MmFixedEntryRecycle( p->pMem, (char *)pCell );
+            else
+            {
+                p->nGood++;
+                p->nVarCounts[pCell->nVars]++;
+
+                for ( i = 0; i < (int)pCell->nVars-1; i++ )
+                {
+                    if ( pCell->Store[2*i] != pCell->Store[2*(i+1)] ) // i and i+1 cannot be symmetric
+                        continue;
+                    // i and i+1 can be symmetric
+                    // find the end of this group
+                    for ( j = i+1; j < (int)pCell->nVars; j++ )
+                        if ( pCell->Store[2*i] != pCell->Store[2*j] ) 
+                            break;
+
+                    if ( pCell->Store[2*i] == pCell->Store[2*i+1] )
+                        p->nSymGroupsE[j-i]++;
+                    else
+                        p->nSymGroups[j-i]++;
+                    i = j - 1;
+                }
+/*
+                if ( pCell->nVars == 3 )
+                {
+                    Extra_PrintBinary( stdout, pCell->uTruth, 32 ); printf( "\n" );
+                    for ( i = 0; i < (int)pCell->nVars; i++ )
+                        printf( "%d=%d/%d  ", pCell->CanonPerm[i], pCell->Store[2*i], pCell->Store[2*i+1] );
+                    printf( "\n" );
+                }
+*/
+            }
+//p->timeTable += clock() - clk2;
+        }
+
+        printf( "VAR %d: Total = %d. Good = %d. Entry = %d. ", k, p->nTotal, p->nGood, sizeof(Cut_Cell_t) );
+        PRT( "Time", clock() - clk );
+        printf( "Cells:  " );
+        for ( i = 0; i <= 9; i++ )
+            printf( "%d=%d ", i, p->nVarCounts[i] );
+        printf( "\nDiffs:  " );
+        for ( i = 0; i <= 9; i++ )
+            printf( "%d=%d ", i, p->nSymGroups[i] );
+        printf( "\nEquals: " );
+        for ( i = 0; i <= 9; i++ )
+            printf( "%d=%d ", i, p->nSymGroupsE[i] );
+        printf( "\n" );
+    }
+//    printf( "\n" );
+    PRT( "Supp ", p->timeSupp );
+    PRT( "Canon", p->timeCanon );
+    PRT( "Table", p->timeTable );
+//    Cut_CManStop( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Check the table.]
+
+  Description [Returns 1 if such a truth table already exists.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_CellTableLookup( Cut_CMan_t * p, Cut_Cell_t * pCell )
+{
+    Cut_Cell_t ** pSlot, * pTemp;
+    unsigned Hash;
+    Hash = Extra_TruthHash( pCell->uTruth, Extra_TruthWordNum( pCell->nVars ) );
+    if ( !st_find_or_add( p->tTable, (char *)Hash, (char ***)&pSlot ) )
+        *pSlot = NULL;
+    for ( pTemp = *pSlot; pTemp; pTemp = pTemp->pNext )
+    {
+        if ( pTemp->nVars != pCell->nVars )
+            continue;
+        if ( Extra_TruthIsEqual(pTemp->uTruth, pCell->uTruth, pCell->nVars) )
+            return 1;
+    }
+    // the entry is new
+    pCell->pNext = *pSlot;
+    *pSlot = pCell;
+    // add it to the variable support list
+    pCell->pNextVar = p->pSameVar[pCell->nVars];
+    p->pSameVar[pCell->nVars] = pCell;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CellSuppMin( Cut_Cell_t * pCell )
+{
+    static unsigned uTemp[1<<(CUT_CELL_MVAR-5)];
+    unsigned * pIn, * pOut, * pTemp;
+    int i, k, Counter, Temp;
+
+    // go backward through the support variables and remove redundant
+    for ( k = pCell->nVars - 1; k >= 0; k-- )
+        if ( !Extra_TruthVarInSupport(pCell->uTruth, pCell->nVars, k) )
+        {
+            // shift all the variables above this one
+            Counter = 0;
+            pIn = pCell->uTruth; pOut = uTemp;
+            for ( i = k; i < (int)pCell->nVars - 1; i++ )
+            {
+                Extra_TruthSwapAdjacentVars( pOut, pIn, pCell->nVars, i );
+                pTemp = pIn; pIn = pOut; pOut = pTemp;
+                // swap the support vars
+                Temp = pCell->CanonPerm[i]; 
+                pCell->CanonPerm[i] = pCell->CanonPerm[i+1];
+                pCell->CanonPerm[i+1] = Temp;
+                Counter++;
+            }
+            // return the function back into its place
+            if ( Counter & 1 )
+                Extra_TruthCopy( pOut, pIn, pCell->nVars );
+            // remove one variable
+            pCell->nVars--;
+//            Extra_PrintBinary( stdout, pCell->uTruth, (1<<pCell->nVars) ); printf( "\n" );
+        }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CellCrossBar( Cut_Cell_t * pCell )
+{
+    static unsigned uTemp0[1<<(CUT_CELL_MVAR-5)];
+    static unsigned uTemp1[1<<(CUT_CELL_MVAR-5)];
+    Extra_TruthCopy( uTemp0, pCell->uTruth, pCell->nVars );
+    Extra_TruthCopy( uTemp1, pCell->uTruth, pCell->nVars );
+    if ( pCell->CanonPhase == 0 )
+    {
+        Extra_TruthCofactor0( uTemp0, pCell->nVars, pCell->CrossBar0 );
+        Extra_TruthCofactor0( uTemp0, pCell->nVars, pCell->CrossBar1 );
+        Extra_TruthCofactor1( uTemp1, pCell->nVars, pCell->CrossBar0 );
+        Extra_TruthCofactor1( uTemp1, pCell->nVars, pCell->CrossBar1 );
+    }
+    else if ( pCell->CanonPhase == 1 )
+    {
+        Extra_TruthCofactor1( uTemp0, pCell->nVars, pCell->CrossBar0 );
+        Extra_TruthCofactor0( uTemp0, pCell->nVars, pCell->CrossBar1 );
+        Extra_TruthCofactor0( uTemp1, pCell->nVars, pCell->CrossBar0 );
+        Extra_TruthCofactor1( uTemp1, pCell->nVars, pCell->CrossBar1 );
+    }
+    else if ( pCell->CanonPhase == 2 )
+    {
+        Extra_TruthCofactor0( uTemp0, pCell->nVars, pCell->CrossBar0 );
+        Extra_TruthCofactor1( uTemp0, pCell->nVars, pCell->CrossBar1 );
+        Extra_TruthCofactor1( uTemp1, pCell->nVars, pCell->CrossBar0 );
+        Extra_TruthCofactor0( uTemp1, pCell->nVars, pCell->CrossBar1 );
+    }
+    else assert( 0 );
+    Extra_TruthMux( pCell->uTruth, uTemp0, uTemp1, pCell->nVars, pCell->CrossBar0 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CellTruthElem( unsigned * InA, unsigned * InB, unsigned * InC, unsigned * pOut, int nVars, int Type )
+{
+    int nWords = Extra_TruthWordNum( nVars );
+    int i;
+
+    assert( Type < 22 );
+    switch ( Type )
+    {
+    // " 0\n",                         // 00   const 0
+    case 0:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = 0;
+        return;
+    // " 1\n",                         // 01   const 1
+    case 1:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = 0xFFFFFFFF;
+        return;
+    // "1 1\n",                        // 02   a
+    case 2:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i];
+        return;
+    // "11 1\n",                       // 03   ab
+    case 3:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i] & InB[i];
+        return;
+    // "11 0\n",                       // 04   (ab)'
+    case 4:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = ~(InA[i] & InB[i]);
+        return;
+    // "10 1\n01 1\n",                 // 05   a<+>b
+    case 5:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i] ^ InB[i];
+        return;
+    // "111 1\n",                      // 06 + abc
+    case 6:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i] & InB[i] & InC[i];
+        return;
+    // "111 0\n",                      // 07   (abc)'
+    case 7:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = ~(InA[i] & InB[i] & InC[i]);
+        return;
+    // "11- 1\n1-1 1\n",               // 08 + a(b+c)
+    case 8:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i] & (InB[i] | InC[i]);
+        return;
+    // "11- 0\n1-1 0\n",               // 09   (a(b+c))'
+    case 9:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = ~(InA[i] & (InB[i] | InC[i]));
+        return;
+    // "111 1\n100 1\n010 1\n001 1\n", // 10 + a<+>b<+>c
+    case 10:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i] ^ InB[i] ^ InC[i];
+        return;
+    // "10- 0\n1-0 0\n011 0\n",        // 11 + a<+>bc
+    case 11:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i] ^ (InB[i] & InC[i]);
+        return;
+    // "101 1\n110 1\n",               // 12 + a(b<+>c)
+    case 12:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = InA[i] & (InB[i] ^ InC[i]);
+        return;
+    // "101 0\n110 0\n",               // 13   (a(b<+>c))'
+    case 13:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = ~(InA[i] & (InB[i] ^ InC[i]));
+        return;
+    // "11- 1\n1-1 1\n-11 1\n",        // 14 + ab+bc+ac
+    case 14:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = (InA[i] & InB[i]) | (InB[i] & InC[i]) | (InA[i] & InC[i]);
+        return;
+    // "111 1\n000 1\n",               // 15 + abc+a'b'c'
+    case 15:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = (InA[i] & InB[i] & InC[i]) | (~InA[i] & ~InB[i] & ~InC[i]);
+        return;
+    // "111 0\n000 0\n",               // 16   (abc+a'b'c')'
+    case 16:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = ~((InA[i] & InB[i] & InC[i]) | (~InA[i] & ~InB[i] & ~InC[i]));
+        return;
+    // "11- 1\n-11 1\n0-1 1\n",        // 17 + ab+bc+a'c
+    case 17:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = (InA[i] & InB[i]) | (InB[i] & InC[i]) | (~InA[i] & InC[i]);
+        return;
+    // "011 1\n101 1\n110 1\n",        // 18 + a'bc+ab'c+abc'
+    case 18:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = (~InA[i] & InB[i] & InC[i]) | (InA[i] & ~InB[i] & InC[i]) | (InA[i] & InB[i] & ~InC[i]);
+        return;
+    // "011 0\n101 0\n110 0\n",        // 19   (a'bc+ab'c+abc')'
+    case 19:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = ~((~InA[i] & InB[i] & InC[i]) | (InA[i] & ~InB[i] & InC[i]) | (InA[i] & InB[i] & ~InC[i]));
+        return;
+    // "100 1\n-11 1\n",               // 20 + ab'c'+bc
+    case 20:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = (InA[i] & ~InB[i] & ~InC[i]) | (InB[i] & InC[i]);
+        return;
+    // "100 0\n-11 0\n"                // 21   (ab'c'+bc)'
+    case 21:
+        for ( i = 0; i < nWords; i++ )
+            pOut[i] = ~((InA[i] & ~InB[i] & ~InC[i]) | (InB[i] & InC[i]));
+        return;
+    }
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Start the precomputation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cut_CMan_t * Cut_CManStart()
+{
+    Cut_CMan_t * p;
+    int i, k;
+    // start the manager
+    assert( sizeof(unsigned) == 4 );
+    p = ALLOC( Cut_CMan_t, 1 );
+    memset( p, 0, sizeof(Cut_CMan_t) );
+    // start the table and the memory manager
+    p->tTable = st_init_table(st_ptrcmp,st_ptrhash);
+    p->pMem = Extra_MmFixedStart( sizeof(Cut_Cell_t) );
+    // set elementary truth tables
+    for ( k = 0; k < CUT_CELL_MVAR; k++ )
+        for ( i = 0; i < (1<<CUT_CELL_MVAR); i++ )
+            if ( i & (1 << k) )
+                p->uInputs[k][i>>5] |= (1 << (i&31));
+    s_pCMan = p;
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CManStop( Cut_CMan_t * p )
+{
+    st_free_table( p->tTable );
+    Extra_MmFixedStop( p->pMem );
+    free( p );
+}
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_CellIsRunning()
+{
+    return s_pCMan != NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_CellDumpToFile()
+{
+    FILE * pFile;
+    Cut_CMan_t * p = s_pCMan;
+    Cut_Cell_t * pTemp;
+    char * pFileName = "celllib22.txt";
+    int NumUsed[10][5] = {{0}};
+    int BoxUsed[22][5] = {{0}};
+    int i, k, Counter;
+    int clk = clock();
+
+    if ( p == NULL )
+    {
+        printf( "Cut_CellDumpToFile: Cell manager is not defined.\n" );
+        return;
+    }
+
+    // count the number of cells used
+    for ( k = CUT_CELL_MVAR; k >= 0; k-- )
+    {
+        for ( pTemp = p->pSameVar[k]; pTemp; pTemp = pTemp->pNextVar )
+        {
+            if ( pTemp->nUsed == 0 )
+                NumUsed[k][0]++;
+            else if ( pTemp->nUsed < 10 )
+                NumUsed[k][1]++;
+            else if ( pTemp->nUsed < 100 )
+                NumUsed[k][2]++;
+            else if ( pTemp->nUsed < 1000 )
+                NumUsed[k][3]++;
+            else 
+                NumUsed[k][4]++;
+
+            for ( i = 0; i < 4; i++ )
+                if ( pTemp->nUsed == 0 )
+                    BoxUsed[ pTemp->Box[i] ][0]++;
+                else if ( pTemp->nUsed < 10 )
+                    BoxUsed[ pTemp->Box[i] ][1]++;
+                else if ( pTemp->nUsed < 100 )
+                    BoxUsed[ pTemp->Box[i] ][2]++;
+                else if ( pTemp->nUsed < 1000 )
+                    BoxUsed[ pTemp->Box[i] ][3]++;
+                else 
+                    BoxUsed[ pTemp->Box[i] ][4]++;
+        }
+    }
+
+    printf( "Functions found = %10d.  Functions not found = %10d.\n", p->nCellFound, p->nCellNotFound );
+    for ( k = 0; k <= CUT_CELL_MVAR; k++ )
+    {
+        printf( "%3d  : ", k );
+        for ( i = 0; i < 5; i++ ) 
+            printf( "%8d ", NumUsed[k][i] );
+        printf( "\n" );
+    }
+    printf( "Box usage:\n" );
+    for ( k = 0; k < 22; k++ )
+    {
+        printf( "%3d  : ", k );
+        for ( i = 0; i < 5; i++ ) 
+            printf( "%8d ", BoxUsed[k][i] );
+        printf( "  %s", s_NP3Names[k] );
+        printf( "\n" );
+    }
+
+    pFile = fopen( pFileName, "w" );
+    if ( pFile == NULL )
+    {
+        printf( "Cut_CellDumpToFile: Cannout open output file.\n" );
+        return;
+    }
+
+    Counter = 0;
+    for ( k = 0; k <= CUT_CELL_MVAR; k++ )
+    {
+        for ( pTemp = p->pSameVar[k]; pTemp; pTemp = pTemp->pNextVar )
+            if ( pTemp->nUsed > 0 )
+            {
+                Extra_PrintHexadecimal( pFile, pTemp->uTruth, (k <= 5? 5 : k) );
+                fprintf( pFile, "\n" );
+                Counter++;
+            }
+        fprintf( pFile, "\n" );
+    }
+    fclose( pFile );
+
+    printf( "Library composed of %d functions is written into file \"%s\".  ", Counter, pFileName );
+
+    PRT( "Time", clock() - clk );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Looks up if the given function exists in the hash table.]
+
+  Description [If the function exists, returns 1, meaning that it can be
+  implemented using two levels of 3-input LUTs. If the function does not 
+  exist, return 0.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_CellTruthLookup( unsigned * pTruth, int nVars )
+{
+    Cut_CMan_t * p = s_pCMan;
+    Cut_Cell_t * pTemp;
+    Cut_Cell_t Cell, * pCell = &Cell;
+    unsigned Hash;
+    int i;
+
+    // cell manager is not defined
+    if ( p == NULL )
+    {
+        printf( "Cut_CellTruthLookup: Cell manager is not defined.\n" );
+        return 0;
+    }
+
+    // canonicize
+    memset( pCell, 0, sizeof(Cut_Cell_t) );
+    pCell->nVars = nVars;
+    Extra_TruthCopy( pCell->uTruth, pTruth, nVars );
+    Cut_CellSuppMin( pCell );
+    // set the elementary permutation
+    for ( i = 0; i < (int)pCell->nVars; i++ )
+        pCell->CanonPerm[i] = i;
+    // canonicize
+    pCell->CanonPhase = Extra_TruthSemiCanonicize( pCell->uTruth, p->puAux, pCell->nVars, pCell->CanonPerm, pCell->Store );
+
+
+    // check if the cell exists
+    Hash = Extra_TruthHash( pCell->uTruth, Extra_TruthWordNum(pCell->nVars) );
+    if ( st_lookup( p->tTable, (char *)Hash, (char **)&pTemp ) )
+    {
+        for ( ; pTemp; pTemp = pTemp->pNext )
+        {
+            if ( pTemp->nVars != pCell->nVars )
+                continue;
+            if ( Extra_TruthIsEqual(pTemp->uTruth, pCell->uTruth, pCell->nVars) )
+            {
+                pTemp->nUsed++;
+                p->nCellFound++;
+                return 1;
+            }
+        }
+    }
+    p->nCellNotFound++;
+    return 0;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutSeq.c b/src/opt/cut/cutSeq.c
new file mode 100644
index 00000000..d36f94f7
--- /dev/null
+++ b/src/opt/cut/cutSeq.c
@@ -0,0 +1,227 @@
+/**CFile****************************************************************
+
+  FileName    [cutSeq.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Sequential cut computation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutSeq.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Shifts all cut leaves of the node by the given number of latches.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cut_NodeShiftCutLeaves( Cut_Cut_t * pList, int nLat )
+{
+    Cut_Cut_t * pTemp;
+    int i;
+    // shift the cuts by as many latches
+    Cut_ListForEachCut( pList, pTemp )
+    {
+        pTemp->uSign = 0;
+        for ( i = 0; i < (int)pTemp->nLeaves; i++ )
+        {
+            pTemp->pLeaves[i] += nLat;
+            pTemp->uSign      |= Cut_NodeSign( pTemp->pLeaves[i] );
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes sequential cuts for the node from its fanins.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeComputeCutsSeq( Cut_Man_t * p, int Node, int Node0, int Node1, int fCompl0, int fCompl1, int nLat0, int nLat1, int fTriv, int CutSetNum )
+{
+    Cut_List_t Super, * pSuper = &Super;
+    Cut_Cut_t * pListNew;
+    int clk;
+    
+    // get the number of cuts at the node
+    p->nNodeCuts = Cut_CutCountList( Cut_NodeReadCutsOld(p, Node) );
+    if ( p->nNodeCuts >= p->pParams->nKeepMax )
+        return;
+
+    // count only the first visit
+    if ( p->nNodeCuts == 0 )
+        p->nNodes++;
+
+    // store the fanin lists
+    p->pStore0[0] = Cut_NodeReadCutsOld( p, Node0 );
+    p->pStore0[1] = Cut_NodeReadCutsNew( p, Node0 );
+    p->pStore1[0] = Cut_NodeReadCutsOld( p, Node1 );
+    p->pStore1[1] = Cut_NodeReadCutsNew( p, Node1 );
+
+    // duplicate the cut lists if fanin nodes are non-standard
+    if ( Node == Node0 || Node == Node1 || Node0 == Node1 )
+    {
+        p->pStore0[0] = Cut_CutDupList( p, p->pStore0[0] );
+        p->pStore0[1] = Cut_CutDupList( p, p->pStore0[1] );
+        p->pStore1[0] = Cut_CutDupList( p, p->pStore1[0] );
+        p->pStore1[1] = Cut_CutDupList( p, p->pStore1[1] );
+    }
+
+    // shift the cuts by as many latches and recompute signatures
+    if ( nLat0 ) Cut_NodeShiftCutLeaves( p->pStore0[0], nLat0 );
+    if ( nLat0 ) Cut_NodeShiftCutLeaves( p->pStore0[1], nLat0 );
+    if ( nLat1 ) Cut_NodeShiftCutLeaves( p->pStore1[0], nLat1 );
+    if ( nLat1 ) Cut_NodeShiftCutLeaves( p->pStore1[1], nLat1 );
+
+    // store the original lists for comparison
+    p->pCompareOld = Cut_NodeReadCutsOld( p, Node );
+    p->pCompareNew = Cut_NodeReadCutsNew( p, Node );
+
+    // merge the old and the new
+clk = clock();
+    Cut_ListStart( pSuper );
+    Cut_NodeDoComputeCuts( p, pSuper, Node, fCompl0, fCompl1, p->pStore0[0], p->pStore1[1], 0, 0 );
+    Cut_NodeDoComputeCuts( p, pSuper, Node, fCompl0, fCompl1, p->pStore0[1], p->pStore1[0], 0, 0 );
+    Cut_NodeDoComputeCuts( p, pSuper, Node, fCompl0, fCompl1, p->pStore0[1], p->pStore1[1], fTriv, 0 );
+    pListNew = Cut_ListFinish( pSuper );
+p->timeMerge += clock() - clk;
+
+    // shift the cuts by as many latches and recompute signatures
+    if ( Node == Node0 || Node == Node1 || Node0 == Node1 )
+    {
+        Cut_CutRecycleList( p, p->pStore0[0] );
+        Cut_CutRecycleList( p, p->pStore0[1] );
+        Cut_CutRecycleList( p, p->pStore1[0] );
+        Cut_CutRecycleList( p, p->pStore1[1] );
+    }
+    else
+    {
+        if ( nLat0 ) Cut_NodeShiftCutLeaves( p->pStore0[0], -nLat0 );
+        if ( nLat0 ) Cut_NodeShiftCutLeaves( p->pStore0[1], -nLat0 );
+        if ( nLat1 ) Cut_NodeShiftCutLeaves( p->pStore1[0], -nLat1 );
+        if ( nLat1 ) Cut_NodeShiftCutLeaves( p->pStore1[1], -nLat1 );
+    }
+
+    // set the lists at the node
+    if ( CutSetNum >= 0 )
+    {
+        assert( Cut_NodeReadCutsTemp(p, CutSetNum) == NULL );
+        Cut_NodeWriteCutsTemp( p, CutSetNum, pListNew );
+    }
+    else
+    {
+        assert( Cut_NodeReadCutsNew(p, Node) == NULL );
+        Cut_NodeWriteCutsNew( p, Node, pListNew );
+    }
+
+    // mark the node if we exceeded the number of cuts
+    if ( p->nNodeCuts >= p->pParams->nKeepMax )
+        p->nCutsLimit++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges the new cuts with the old cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeNewMergeWithOld( Cut_Man_t * p, int Node )
+{
+    Cut_Cut_t * pListOld, * pListNew, * pList;
+    // get the new cuts
+    pListNew = Cut_NodeReadCutsNew( p, Node );
+    if ( pListNew == NULL )
+        return;
+    Cut_NodeWriteCutsNew( p, Node, NULL );
+    // get the old cuts
+    pListOld = Cut_NodeReadCutsOld( p, Node );
+    if ( pListOld == NULL )
+    {
+        Cut_NodeWriteCutsOld( p, Node, pListNew );
+        return;
+    }
+    // merge the lists
+    pList = Cut_CutMergeLists( pListOld, pListNew );
+    Cut_NodeWriteCutsOld( p, Node, pList );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Transfers the temporary cuts to be the new cuts.]
+
+  Description [Returns 1 if something was transferred.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cut_NodeTempTransferToNew( Cut_Man_t * p, int Node, int CutSetNum )
+{
+    Cut_Cut_t * pList;
+    pList = Cut_NodeReadCutsTemp( p, CutSetNum );
+    Cut_NodeWriteCutsTemp( p, CutSetNum, NULL );
+    Cut_NodeWriteCutsNew( p, Node, pList );
+    return pList != NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfers the old cuts to be the new cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_NodeOldTransferToNew( Cut_Man_t * p, int Node )
+{
+    Cut_Cut_t * pList;
+    pList = Cut_NodeReadCutsOld( p, Node );
+    Cut_NodeWriteCutsOld( p, Node, NULL );
+    Cut_NodeWriteCutsNew( p, Node, pList );
+//    Cut_CutListVerify( pList );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/cutTruth.c b/src/opt/cut/cutTruth.c
new file mode 100644
index 00000000..c3514ad7
--- /dev/null
+++ b/src/opt/cut/cutTruth.c
@@ -0,0 +1,226 @@
+/**CFile****************************************************************
+
+  FileName    [cutTruth.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [K-feasible cut computation package.]
+
+  Synopsis    [Incremental truth table computation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: cutTruth.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "cutInt.h"
+
+/* 
+    Truth tables computed in this package are represented as bit-strings
+    stored in the cut data structure. Cuts of any number of inputs have 
+    the truth table with 2^k bits, where k is the max number of cut inputs.
+*/
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+extern int nTotal = 0;
+extern int nGood  = 0;
+extern int nEqual = 0;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the stretching phase of the cut w.r.t. the merged cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline unsigned Cut_TruthPhase( Cut_Cut_t * pCut, Cut_Cut_t * pCut1 )
+{
+    unsigned uPhase = 0;
+    int i, k;
+    for ( i = k = 0; i < (int)pCut->nLeaves; i++ )
+    {
+        if ( k == (int)pCut1->nLeaves )
+            break;
+        if ( pCut->pLeaves[i] < pCut1->pLeaves[k] )
+            continue;
+        assert( pCut->pLeaves[i] == pCut1->pLeaves[k] );
+        uPhase |= (1 << i);
+        k++;
+    }
+    return uPhase;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs truth table computation.]
+
+  Description [This procedure cannot be used while recording oracle
+  because it will overwrite Num0 and Num1.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_TruthNCanonicize( Cut_Cut_t * pCut )
+{
+    unsigned uTruth;
+    unsigned * uCanon2;
+    char * pPhases2;
+    assert( pCut->nVarsMax < 6 );
+
+    // get the direct truth table
+    uTruth = *Cut_CutReadTruth(pCut);
+
+    // compute the direct truth table
+    Extra_TruthCanonFastN( pCut->nVarsMax, pCut->nLeaves, &uTruth, &uCanon2, &pPhases2 );
+//    uCanon[0] = uCanon2[0];
+//    uCanon[1] = (p->nVarsMax == 6)? uCanon2[1] : uCanon2[0];
+//    uPhases[0] = pPhases2[0];
+    pCut->uCanon0 = uCanon2[0];
+    pCut->Num0    = pPhases2[0];
+
+    // get the complemented truth table
+    uTruth = ~*Cut_CutReadTruth(pCut);
+
+    // compute the direct truth table
+    Extra_TruthCanonFastN( pCut->nVarsMax, pCut->nLeaves, &uTruth, &uCanon2, &pPhases2 );
+//    uCanon[0] = uCanon2[0];
+//    uCanon[1] = (p->nVarsMax == 6)? uCanon2[1] : uCanon2[0];
+//    uPhases[0] = pPhases2[0];
+    pCut->uCanon1 = uCanon2[0];
+    pCut->Num1    = pPhases2[0];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs truth table computation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_TruthComputeOld( Cut_Cut_t * pCut, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1, int fCompl0, int fCompl1 )
+{
+    static unsigned uTruth0[8], uTruth1[8];
+    int nTruthWords = Cut_TruthWords( pCut->nVarsMax );
+    unsigned * pTruthRes;
+    int i, uPhase;
+
+    // permute the first table
+    uPhase = Cut_TruthPhase( pCut, pCut0 );
+    Extra_TruthExpand( pCut->nVarsMax, nTruthWords, Cut_CutReadTruth(pCut0), uPhase, uTruth0 );
+    if ( fCompl0 ) 
+    {
+        for ( i = 0; i < nTruthWords; i++ )
+            uTruth0[i] = ~uTruth0[i];
+    }
+
+    // permute the second table
+    uPhase = Cut_TruthPhase( pCut, pCut1 );
+    Extra_TruthExpand( pCut->nVarsMax, nTruthWords, Cut_CutReadTruth(pCut1), uPhase, uTruth1 );
+    if ( fCompl1 ) 
+    {
+        for ( i = 0; i < nTruthWords; i++ )
+            uTruth1[i] = ~uTruth1[i];
+    }
+
+    // write the resulting table
+    pTruthRes = Cut_CutReadTruth(pCut);
+
+    if ( pCut->fCompl )
+    {
+        for ( i = 0; i < nTruthWords; i++ )
+            pTruthRes[i] = ~(uTruth0[i] & uTruth1[i]);
+    }
+    else
+    {
+        for ( i = 0; i < nTruthWords; i++ )
+            pTruthRes[i] = uTruth0[i] & uTruth1[i];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs truth table computation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cut_TruthCompute( Cut_Man_t * p, Cut_Cut_t * pCut, Cut_Cut_t * pCut0, Cut_Cut_t * pCut1, int fCompl0, int fCompl1 )
+{
+    // permute the first table
+    if ( fCompl0 ) 
+        Extra_TruthNot( p->puTemp[0], Cut_CutReadTruth(pCut0), pCut->nVarsMax );
+    else
+        Extra_TruthCopy( p->puTemp[0], Cut_CutReadTruth(pCut0), pCut->nVarsMax );
+    Extra_TruthStretch( p->puTemp[2], p->puTemp[0], pCut0->nLeaves, pCut->nVarsMax, Cut_TruthPhase(pCut, pCut0) );
+    // permute the second table
+    if ( fCompl1 ) 
+        Extra_TruthNot( p->puTemp[1], Cut_CutReadTruth(pCut1), pCut->nVarsMax );
+    else
+        Extra_TruthCopy( p->puTemp[1], Cut_CutReadTruth(pCut1), pCut->nVarsMax );
+    Extra_TruthStretch( p->puTemp[3], p->puTemp[1], pCut1->nLeaves, pCut->nVarsMax, Cut_TruthPhase(pCut, pCut1) );
+    // produce the resulting table
+    if ( pCut->fCompl )
+        Extra_TruthNand( Cut_CutReadTruth(pCut), p->puTemp[2], p->puTemp[3], pCut->nVarsMax );
+    else
+        Extra_TruthAnd( Cut_CutReadTruth(pCut), p->puTemp[2], p->puTemp[3], pCut->nVarsMax );
+
+//    Ivy_TruthTestOne( *Cut_CutReadTruth(pCut) );
+
+    // quit if no fancy computation is needed
+    if ( !p->pParams->fFancy )
+        return;
+
+    if ( pCut->nLeaves != 7 )
+        return;
+
+    // count the total number of truth tables computed
+    nTotal++;
+
+    // MAPPING INTO ALTERA 6-2 LOGIC BLOCKS
+    // call this procedure to find the minimum number of common variables in the cofactors
+    // if this number is less or equal than 3, the cut can be implemented using the 6-2 logic block
+    if ( Extra_TruthMinCofSuppOverlap( Cut_CutReadTruth(pCut), pCut->nVarsMax, NULL ) <= 4 )
+        nGood++;
+
+    // MAPPING INTO ACTEL 2x2 CELLS
+    // call this procedure to see if a semi-canonical form can be found in the lookup table 
+    // (if it exists, then a two-level 3-input LUT implementation of the cut exists)
+    // Before this procedure is called, cell manager should be defined by calling
+    // Cut_CellLoad (make sure file "cells22_daomap_iwls.txt" is available in the working dir)
+//    if ( Cut_CellIsRunning() && pCut->nVarsMax <= 9 )
+//        nGood += Cut_CellTruthLookup( Cut_CutReadTruth(pCut), pCut->nVarsMax );
+}
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/cut/module.make b/src/opt/cut/module.make
new file mode 100644
index 00000000..132e730b
--- /dev/null
+++ b/src/opt/cut/module.make
@@ -0,0 +1,9 @@
+SRC +=  src/opt/cut/cutApi.c \
+        src/opt/cut/cutCut.c \
+        src/opt/cut/cutMan.c \
+        src/opt/cut/cutMerge.c \
+        src/opt/cut/cutNode.c \
+        src/opt/cut/cutOracle.c \
+        src/opt/cut/cutPre22.c \
+        src/opt/cut/cutSeq.c \
+        src/opt/cut/cutTruth.c 
diff --git a/src/opt/dec/dec.h b/src/opt/dec/dec.h
new file mode 100644
index 00000000..41d22649
--- /dev/null
+++ b/src/opt/dec/dec.h
@@ -0,0 +1,719 @@
+/**CFile****************************************************************
+
+  FileName    [dec.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [A simple decomposition tree/node data structure and its APIs.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: dec.h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __DEC_H__
+#define __DEC_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Dec_Edge_t_ Dec_Edge_t;
+struct Dec_Edge_t_
+{
+    unsigned          fCompl   :  1;   // the complemented bit
+    unsigned          Node     : 30;   // the decomposition node pointed by the edge
+};
+
+typedef struct Dec_Node_t_ Dec_Node_t;
+struct Dec_Node_t_
+{
+    Dec_Edge_t        eEdge0;          // the left child of the node
+    Dec_Edge_t        eEdge1;          // the right child of the node
+    // other info
+    void *            pFunc;           // the function of the node (BDD or AIG)
+    unsigned          Level    : 14;   // the level of this node in the global AIG
+    // printing info 
+    unsigned          fNodeOr  :  1;   // marks the original OR node
+    unsigned          fCompl0  :  1;   // marks the original complemented edge
+    unsigned          fCompl1  :  1;   // marks the original complemented edge
+    // latch info
+    unsigned          nLat0    :  5;   // the number of latches on the first edge
+    unsigned          nLat1    :  5;   // the number of latches on the second edge
+    unsigned          nLat2    :  5;   // the number of latches on the output edge
+};
+
+typedef struct Dec_Graph_t_ Dec_Graph_t;
+struct Dec_Graph_t_
+{
+    int               fConst;          // marks the constant 1 graph
+    int               nLeaves;         // the number of leaves
+    int               nSize;           // the number of nodes (including the leaves) 
+    int               nCap;            // the number of allocated nodes
+    Dec_Node_t *      pNodes;          // the array of leaves and internal nodes
+    Dec_Edge_t        eRoot;           // the pointer to the topmost node
+};
+
+typedef struct Dec_Man_t_ Dec_Man_t;
+struct Dec_Man_t_
+{
+    void *            pMvcMem;         // memory manager for MVC cover (used for factoring)
+    Vec_Int_t *       vCubes;          // storage for cubes
+    Vec_Int_t *       vLits;           // storage for literals 
+    // precomputation information about 4-variable functions
+    unsigned short *  puCanons;        // canonical forms
+    char *            pPhases;         // canonical phases
+    char *            pPerms;          // canonical permutations
+    unsigned char *   pMap;            // mapping of functions into class numbers
+};
+
+
+////////////////////////////////////////////////////////////////////////
+///                        ITERATORS                                 ///
+////////////////////////////////////////////////////////////////////////
+
+// interator throught the leaves
+#define Dec_GraphForEachLeaf( pGraph, pLeaf, i )                                              \
+    for ( i = 0; (i < (pGraph)->nLeaves) && (((pLeaf) = Dec_GraphNode(pGraph, i)), 1); i++ )
+// interator throught the internal nodes
+#define Dec_GraphForEachNode( pGraph, pAnd, i )                                               \
+    for ( i = (pGraph)->nLeaves; (i < (pGraph)->nSize) && (((pAnd) = Dec_GraphNode(pGraph, i)), 1); i++ )
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== decAbc.c ========================================================*/
+extern Abc_Obj_t *    Dec_GraphToNetwork( Abc_Ntk_t * pNtk, Dec_Graph_t * pGraph );
+extern Abc_Obj_t *    Dec_GraphToNetworkNoStrash( Abc_Ntk_t * pNtk, Dec_Graph_t * pGraph );
+extern int            Dec_GraphToNetworkCount( Abc_Obj_t * pRoot, Dec_Graph_t * pGraph, int NodeMax, int LevelMax );
+extern void           Dec_GraphUpdateNetwork( Abc_Obj_t * pRoot, Dec_Graph_t * pGraph, bool fUpdateLevel, int nGain );
+/*=== decFactor.c ========================================================*/
+extern Dec_Graph_t *  Dec_Factor( char * pSop );
+/*=== decMan.c ========================================================*/
+extern Dec_Man_t *    Dec_ManStart();
+extern void           Dec_ManStop( Dec_Man_t * p );
+/*=== decPrint.c ========================================================*/
+extern void           Dec_GraphPrint( FILE * pFile, Dec_Graph_t * pGraph, char * pNamesIn[], char * pNameOut );
+/*=== decUtil.c ========================================================*/
+extern DdNode *       Dec_GraphDeriveBdd( DdManager * dd, Dec_Graph_t * pGraph );
+extern unsigned       Dec_GraphDeriveTruth( Dec_Graph_t * pGraph );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Creates an edge pointing to the node in the given polarity.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Edge_t Dec_EdgeCreate( int Node, int fCompl )   
+{
+    Dec_Edge_t eEdge = { fCompl, Node }; 
+    return eEdge; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts the edge into unsigned integer.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline unsigned Dec_EdgeToInt( Dec_Edge_t eEdge )   
+{
+    return (eEdge.Node << 1) | eEdge.fCompl; 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts unsigned integer into the edge.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Edge_t Dec_IntToEdge( unsigned Edge )   
+{
+    return Dec_EdgeCreate( Edge >> 1, Edge & 1 ); 
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts the edge into unsigned integer.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline unsigned Dec_EdgeToInt_( Dec_Edge_t eEdge )   
+{
+    return *(unsigned *)&eEdge;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts unsigned integer into the edge.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Edge_t Dec_IntToEdge_( unsigned Edge )   
+{
+    return *(Dec_Edge_t *)&Edge;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates a graph with the given number of leaves.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Graph_t * Dec_GraphCreate( int nLeaves )   
+{
+    Dec_Graph_t * pGraph;
+    pGraph = ALLOC( Dec_Graph_t, 1 );
+    memset( pGraph, 0, sizeof(Dec_Graph_t) );
+    pGraph->nLeaves = nLeaves;
+    pGraph->nSize = nLeaves;
+    pGraph->nCap = 2 * nLeaves + 50;
+    pGraph->pNodes = ALLOC( Dec_Node_t, pGraph->nCap );
+    memset( pGraph->pNodes, 0, sizeof(Dec_Node_t) * pGraph->nSize );
+    return pGraph;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates constant 0 graph.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Graph_t * Dec_GraphCreateConst0()   
+{
+    Dec_Graph_t * pGraph;
+    pGraph = ALLOC( Dec_Graph_t, 1 );
+    memset( pGraph, 0, sizeof(Dec_Graph_t) );
+    pGraph->fConst = 1;
+    pGraph->eRoot.fCompl = 1;
+    return pGraph;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates constant 1 graph.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Graph_t * Dec_GraphCreateConst1()   
+{
+    Dec_Graph_t * pGraph;
+    pGraph = ALLOC( Dec_Graph_t, 1 );
+    memset( pGraph, 0, sizeof(Dec_Graph_t) );
+    pGraph->fConst = 1;
+    return pGraph;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the literal graph.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Graph_t * Dec_GraphCreateLeaf( int iLeaf, int nLeaves, int fCompl )   
+{
+    Dec_Graph_t * pGraph;
+    assert( 0 <= iLeaf && iLeaf < nLeaves );
+    pGraph = Dec_GraphCreate( nLeaves );
+    pGraph->eRoot.Node   = iLeaf;
+    pGraph->eRoot.fCompl = fCompl;
+    return pGraph;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates a graph with the given number of leaves.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Dec_GraphFree( Dec_Graph_t * pGraph )   
+{
+    FREE( pGraph->pNodes );
+    free( pGraph );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the graph is a constant.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline bool Dec_GraphIsConst( Dec_Graph_t * pGraph )   
+{
+    return pGraph->fConst;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the graph is constant 0.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline bool Dec_GraphIsConst0( Dec_Graph_t * pGraph )   
+{
+    return pGraph->fConst && pGraph->eRoot.fCompl;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the graph is constant 1.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline bool Dec_GraphIsConst1( Dec_Graph_t * pGraph )   
+{
+    return pGraph->fConst && !pGraph->eRoot.fCompl;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the graph is complemented.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline bool Dec_GraphIsComplement( Dec_Graph_t * pGraph )   
+{
+    return pGraph->eRoot.fCompl;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks if the graph is complemented.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Dec_GraphComplement( Dec_Graph_t * pGraph )   
+{
+    pGraph->eRoot.fCompl ^= 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the number of leaves.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Dec_GraphLeaveNum( Dec_Graph_t * pGraph )   
+{
+    return pGraph->nLeaves;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the number of internal nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Dec_GraphNodeNum( Dec_Graph_t * pGraph )   
+{
+    return pGraph->nSize - pGraph->nLeaves;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Node_t * Dec_GraphNode( Dec_Graph_t * pGraph, int i )   
+{
+    return pGraph->pNodes + i;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the pointer to the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Node_t * Dec_GraphNodeLast( Dec_Graph_t * pGraph )   
+{
+    return pGraph->pNodes + pGraph->nSize - 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the number of the given node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Dec_GraphNodeInt( Dec_Graph_t * pGraph, Dec_Node_t * pNode )   
+{
+    return pNode - pGraph->pNodes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Check if the graph represents elementary variable.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline bool Dec_GraphIsVar( Dec_Graph_t * pGraph )   
+{
+    return pGraph->eRoot.Node < (unsigned)pGraph->nLeaves;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Check if the graph represents elementary variable.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline bool Dec_GraphNodeIsVar( Dec_Graph_t * pGraph, Dec_Node_t * pNode )   
+{
+    return Dec_GraphNodeInt(pGraph,pNode) < pGraph->nLeaves;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the elementary variable elementary variable.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Node_t * Dec_GraphVar( Dec_Graph_t * pGraph )   
+{
+    assert( Dec_GraphIsVar( pGraph ) );
+    return Dec_GraphNode( pGraph, pGraph->eRoot.Node );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the number of the elementary variable.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Dec_GraphVarInt( Dec_Graph_t * pGraph )   
+{
+    assert( Dec_GraphIsVar( pGraph ) );
+    return Dec_GraphNodeInt( pGraph, Dec_GraphVar(pGraph) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the root of the graph.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Dec_GraphSetRoot( Dec_Graph_t * pGraph, Dec_Edge_t eRoot )   
+{
+    pGraph->eRoot = eRoot;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Appends a new node to the graph.]
+
+  Description [This procedure is meant for internal use.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Node_t * Dec_GraphAppendNode( Dec_Graph_t * pGraph )   
+{
+    Dec_Node_t * pNode;
+    if ( pGraph->nSize == pGraph->nCap )
+    {
+        pGraph->pNodes = REALLOC( Dec_Node_t, pGraph->pNodes, 2 * pGraph->nCap ); 
+        pGraph->nCap   = 2 * pGraph->nCap;
+    }
+    pNode = pGraph->pNodes + pGraph->nSize++;
+    memset( pNode, 0, sizeof(Dec_Node_t) );
+    return pNode;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates an AND node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Edge_t Dec_GraphAddNodeAnd( Dec_Graph_t * pGraph, Dec_Edge_t eEdge0, Dec_Edge_t eEdge1 )
+{
+    Dec_Node_t * pNode;
+    // get the new node
+    pNode = Dec_GraphAppendNode( pGraph );
+    // set the inputs and other info
+    pNode->eEdge0 = eEdge0;
+    pNode->eEdge1 = eEdge1;
+    pNode->fCompl0 = eEdge0.fCompl;
+    pNode->fCompl1 = eEdge1.fCompl;
+    return Dec_EdgeCreate( pGraph->nSize - 1, 0 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates an OR node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Edge_t Dec_GraphAddNodeOr( Dec_Graph_t * pGraph, Dec_Edge_t eEdge0, Dec_Edge_t eEdge1 )
+{
+    Dec_Node_t * pNode;
+    // get the new node
+    pNode = Dec_GraphAppendNode( pGraph );
+    // set the inputs and other info
+    pNode->eEdge0 = eEdge0;
+    pNode->eEdge1 = eEdge1;
+    pNode->fCompl0 = eEdge0.fCompl;
+    pNode->fCompl1 = eEdge1.fCompl;
+    // make adjustments for the OR gate
+    pNode->fNodeOr = 1;
+    pNode->eEdge0.fCompl = !pNode->eEdge0.fCompl;
+    pNode->eEdge1.fCompl = !pNode->eEdge1.fCompl;
+    return Dec_EdgeCreate( pGraph->nSize - 1, 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates an XOR node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Edge_t Dec_GraphAddNodeXor( Dec_Graph_t * pGraph, Dec_Edge_t eEdge0, Dec_Edge_t eEdge1, int Type )
+{
+    Dec_Edge_t eNode0, eNode1, eNode;
+    if ( Type == 0 )
+    {
+        // derive the first AND
+        eEdge0.fCompl ^= 1;
+        eNode0 = Dec_GraphAddNodeAnd( pGraph, eEdge0, eEdge1 );
+        eEdge0.fCompl ^= 1;
+        // derive the second AND
+        eEdge1.fCompl ^= 1;
+        eNode1 = Dec_GraphAddNodeAnd( pGraph, eEdge0, eEdge1 );
+        // derive the final OR
+        eNode = Dec_GraphAddNodeOr( pGraph, eNode0, eNode1 );
+    }
+    else
+    {
+        // derive the first AND
+        eNode0 = Dec_GraphAddNodeAnd( pGraph, eEdge0, eEdge1 );
+        // derive the second AND
+        eEdge0.fCompl ^= 1;
+        eEdge1.fCompl ^= 1;
+        eNode1 = Dec_GraphAddNodeAnd( pGraph, eEdge0, eEdge1 );
+        // derive the final OR
+        eNode = Dec_GraphAddNodeOr( pGraph, eNode0, eNode1 );
+        eNode.fCompl ^= 1;
+    }
+    return eNode;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates an XOR node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Dec_Edge_t Dec_GraphAddNodeMux( Dec_Graph_t * pGraph, Dec_Edge_t eEdgeC, Dec_Edge_t eEdgeT, Dec_Edge_t eEdgeE, int Type )
+{
+    Dec_Edge_t eNode0, eNode1, eNode;
+    if ( Type == 0 )
+    {
+        // derive the first AND
+        eNode0 = Dec_GraphAddNodeAnd( pGraph, eEdgeC, eEdgeT );
+        // derive the second AND
+        eEdgeC.fCompl ^= 1;
+        eNode1 = Dec_GraphAddNodeAnd( pGraph, eEdgeC, eEdgeE );
+        // derive the final OR
+        eNode = Dec_GraphAddNodeOr( pGraph, eNode0, eNode1 );
+    }
+    else
+    {
+        // complement the arguments
+        eEdgeT.fCompl ^= 1;
+        eEdgeE.fCompl ^= 1;
+        // derive the first AND
+        eNode0 = Dec_GraphAddNodeAnd( pGraph, eEdgeC, eEdgeT );
+        // derive the second AND
+        eEdgeC.fCompl ^= 1;
+        eNode1 = Dec_GraphAddNodeAnd( pGraph, eEdgeC, eEdgeE );
+        // derive the final OR
+        eNode = Dec_GraphAddNodeOr( pGraph, eNode0, eNode1 );
+        eNode.fCompl ^= 1;
+    }
+    return eNode;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/dec/decAbc.c b/src/opt/dec/decAbc.c
new file mode 100644
index 00000000..bd960c14
--- /dev/null
+++ b/src/opt/dec/decAbc.c
@@ -0,0 +1,305 @@
+/**CFile****************************************************************
+
+  FileName    [decAbc.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Interface between the decomposition package and ABC network.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: decAbc.c,v 1.1 2003/05/22 19:20:05 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "dec.h"
+#include "ivy.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the decomposition graph into the AIG.]
+
+  Description [AIG nodes for the fanins should be assigned to pNode->pFunc
+  of the leaves of the graph before calling this procedure.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Dec_GraphToNetwork( Abc_Ntk_t * pNtk, Dec_Graph_t * pGraph )
+{
+    Abc_Obj_t * pAnd0, * pAnd1;
+    Dec_Node_t * pNode;
+    int i;
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Abc_ObjNotCond( Abc_AigConst1(pNtk), Dec_GraphIsComplement(pGraph) );
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+        return Abc_ObjNotCond( Dec_GraphVar(pGraph)->pFunc, Dec_GraphIsComplement(pGraph) );
+    // build the AIG nodes corresponding to the AND gates of the graph
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        pAnd0 = Abc_ObjNotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
+        pAnd1 = Abc_ObjNotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
+        pNode->pFunc = Abc_AigAnd( pNtk->pManFunc, pAnd0, pAnd1 );
+    }
+    // complement the result if necessary
+    return Abc_ObjNotCond( pNode->pFunc, Dec_GraphIsComplement(pGraph) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the decomposition graph into the AIG.]
+
+  Description [AIG nodes for the fanins should be assigned to pNode->pFunc
+  of the leaves of the graph before calling this procedure.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Dec_GraphToNetworkNoStrash( Abc_Ntk_t * pNtk, Dec_Graph_t * pGraph )
+{
+    Abc_Obj_t * pAnd, * pAnd0, * pAnd1;
+    Dec_Node_t * pNode;
+    int i;
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Abc_ObjNotCond( Abc_AigConst1(pNtk), Dec_GraphIsComplement(pGraph) );
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+        return Abc_ObjNotCond( Dec_GraphVar(pGraph)->pFunc, Dec_GraphIsComplement(pGraph) );
+    // build the AIG nodes corresponding to the AND gates of the graph
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        pAnd0 = Abc_ObjNotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
+        pAnd1 = Abc_ObjNotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
+//        pNode->pFunc = Abc_AigAnd( pNtk->pManFunc, pAnd0, pAnd1 );
+        pAnd = Abc_NtkCreateNode( pNtk );
+        Abc_ObjAddFanin( pAnd, pAnd0 );
+        Abc_ObjAddFanin( pAnd, pAnd1 );
+        pNode->pFunc = pAnd;
+    }
+    // complement the result if necessary
+    return Abc_ObjNotCond( pNode->pFunc, Dec_GraphIsComplement(pGraph) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of new nodes added when using this graph.]
+
+  Description [AIG nodes for the fanins should be assigned to pNode->pFunc 
+  of the leaves of the graph before calling this procedure. 
+  Returns -1 if the number of nodes and levels exceeded the given limit or 
+  the number of levels exceeded the maximum allowed level.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Dec_GraphToNetworkCount( Abc_Obj_t * pRoot, Dec_Graph_t * pGraph, int NodeMax, int LevelMax )
+{
+    Abc_Aig_t * pMan = pRoot->pNtk->pManFunc;
+    Dec_Node_t * pNode, * pNode0, * pNode1;
+    Abc_Obj_t * pAnd, * pAnd0, * pAnd1;
+    int i, Counter, LevelNew, LevelOld;
+    // check for constant function or a literal
+    if ( Dec_GraphIsConst(pGraph) || Dec_GraphIsVar(pGraph) )
+        return 0;
+    // set the levels of the leaves
+    Dec_GraphForEachLeaf( pGraph, pNode, i )
+        pNode->Level = Abc_ObjRegular(pNode->pFunc)->Level;
+    // compute the AIG size after adding the internal nodes
+    Counter = 0;
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        // get the children of this node
+        pNode0 = Dec_GraphNode( pGraph, pNode->eEdge0.Node );
+        pNode1 = Dec_GraphNode( pGraph, pNode->eEdge1.Node );
+        // get the AIG nodes corresponding to the children 
+        pAnd0 = pNode0->pFunc; 
+        pAnd1 = pNode1->pFunc; 
+        if ( pAnd0 && pAnd1 )
+        {
+            // if they are both present, find the resulting node
+            pAnd0 = Abc_ObjNotCond( pAnd0, pNode->eEdge0.fCompl );
+            pAnd1 = Abc_ObjNotCond( pAnd1, pNode->eEdge1.fCompl );
+            pAnd  = Abc_AigAndLookup( pMan, pAnd0, pAnd1 );
+            // return -1 if the node is the same as the original root
+            if ( Abc_ObjRegular(pAnd) == pRoot )
+                return -1;
+        }
+        else
+            pAnd = NULL;
+        // count the number of added nodes
+        if ( pAnd == NULL || Abc_NodeIsTravIdCurrent(Abc_ObjRegular(pAnd)) )
+        {
+            if ( ++Counter > NodeMax )
+                return -1;
+        }
+        // count the number of new levels
+        LevelNew = 1 + ABC_MAX( pNode0->Level, pNode1->Level );
+        if ( pAnd )
+        {
+            if ( Abc_ObjRegular(pAnd) == Abc_AigConst1(pRoot->pNtk) )
+                LevelNew = 0;
+            else if ( Abc_ObjRegular(pAnd) == Abc_ObjRegular(pAnd0) )
+                LevelNew = (int)Abc_ObjRegular(pAnd0)->Level;
+            else if ( Abc_ObjRegular(pAnd) == Abc_ObjRegular(pAnd1) )
+                LevelNew = (int)Abc_ObjRegular(pAnd1)->Level;
+            LevelOld = (int)Abc_ObjRegular(pAnd)->Level;
+//            assert( LevelNew == LevelOld );
+        }
+        if ( LevelNew > LevelMax )
+            return -1;
+        pNode->pFunc = pAnd;
+        pNode->Level = LevelNew;
+    }
+    return Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Replaces MFFC of the node by the new factored form.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Dec_GraphUpdateNetwork( Abc_Obj_t * pRoot, Dec_Graph_t * pGraph, bool fUpdateLevel, int nGain )
+{
+    Abc_Obj_t * pRootNew;
+    Abc_Ntk_t * pNtk = pRoot->pNtk;
+    int nNodesNew, nNodesOld;
+    nNodesOld = Abc_NtkNodeNum(pNtk);
+    // create the new structure of nodes
+    pRootNew = Dec_GraphToNetwork( pNtk, pGraph );
+    // remove the old nodes
+    Abc_AigReplace( pNtk->pManFunc, pRoot, pRootNew, fUpdateLevel );
+    // compare the gains
+    nNodesNew = Abc_NtkNodeNum(pNtk);
+    assert( nGain <= nNodesOld - nNodesNew );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the decomposition graph into the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Hop_Obj_t * Dec_GraphToNetworkAig( Hop_Man_t * pMan, Dec_Graph_t * pGraph )
+{
+    Dec_Node_t * pNode;
+    Hop_Obj_t * pAnd0, * pAnd1;
+    int i;
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Hop_NotCond( Hop_ManConst1(pMan), Dec_GraphIsComplement(pGraph) );
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+        return Hop_NotCond( Dec_GraphVar(pGraph)->pFunc, Dec_GraphIsComplement(pGraph) );
+    // build the AIG nodes corresponding to the AND gates of the graph
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        pAnd0 = Hop_NotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
+        pAnd1 = Hop_NotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
+        pNode->pFunc = Hop_And( pMan, pAnd0, pAnd1 );
+    }
+    // complement the result if necessary
+    return Hop_NotCond( pNode->pFunc, Dec_GraphIsComplement(pGraph) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Strashes one logic node using its SOP.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Hop_Obj_t * Dec_GraphFactorSop( Hop_Man_t * pMan, char * pSop )
+{
+    Hop_Obj_t * pFunc;
+    Dec_Graph_t * pFForm;
+    Dec_Node_t * pNode;
+    int i;
+    // perform factoring
+    pFForm = Dec_Factor( pSop );
+    // collect the fanins
+    Dec_GraphForEachLeaf( pFForm, pNode, i )
+        pNode->pFunc = Hop_IthVar( pMan, i );
+    // perform strashing
+    pFunc = Dec_GraphToNetworkAig( pMan, pFForm );
+    Dec_GraphFree( pFForm );
+    return pFunc;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the decomposition graph into the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ivy_Obj_t * Dec_GraphToNetworkIvy( Ivy_Man_t * pMan, Dec_Graph_t * pGraph )
+{
+    Dec_Node_t * pNode;
+    Ivy_Obj_t * pAnd0, * pAnd1;
+    int i;
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Ivy_NotCond( Ivy_ManConst1(pMan), Dec_GraphIsComplement(pGraph) );
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+        return Ivy_NotCond( Dec_GraphVar(pGraph)->pFunc, Dec_GraphIsComplement(pGraph) );
+    // build the AIG nodes corresponding to the AND gates of the graph
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        pAnd0 = Ivy_NotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
+        pAnd1 = Ivy_NotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
+        pNode->pFunc = Ivy_And( pMan, pAnd0, pAnd1 );
+    }
+    // complement the result if necessary
+    return Ivy_NotCond( pNode->pFunc, Dec_GraphIsComplement(pGraph) );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/dec/decFactor.c b/src/opt/dec/decFactor.c
new file mode 100644
index 00000000..dca422ea
--- /dev/null
+++ b/src/opt/dec/decFactor.c
@@ -0,0 +1,392 @@
+/**CFile****************************************************************
+
+  FileName    [ftFactor.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Procedures for algebraic factoring.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: ftFactor.c,v 1.3 2003/09/01 04:56:43 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "main.h"
+#include "mvc.h"
+#include "dec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Dec_Edge_t       Dec_Factor_rec( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover );
+static Dec_Edge_t       Dec_FactorLF_rec( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover, Mvc_Cover_t * pSimple );
+static Dec_Edge_t       Dec_FactorTrivial( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover );
+static Dec_Edge_t       Dec_FactorTrivialCube( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover, Mvc_Cube_t * pCube, Vec_Int_t * vEdgeLits );
+static Dec_Edge_t       Dec_FactorTrivialTree_rec( Dec_Graph_t * pFForm, Dec_Edge_t * peNodes, int nNodes, int fNodeOr );
+static int              Dec_FactorVerify( char * pSop, Dec_Graph_t * pFForm );
+static Mvc_Cover_t *    Dec_ConvertSopToMvc( char * pSop );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Factors the cover.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Graph_t * Dec_Factor( char * pSop )
+{
+    Mvc_Cover_t * pCover;
+    Dec_Graph_t * pFForm;
+    Dec_Edge_t eRoot;
+
+    // derive the cover from the SOP representation
+    pCover = Dec_ConvertSopToMvc( pSop );
+
+    // make sure the cover is CCS free (should be done before CST)
+    Mvc_CoverContain( pCover );
+    // check for trivial functions
+    if ( Mvc_CoverIsEmpty(pCover) )
+    {
+        Mvc_CoverFree( pCover );
+        return Dec_GraphCreateConst0();
+    }
+    if ( Mvc_CoverIsTautology(pCover) )
+    {
+        Mvc_CoverFree( pCover );
+        return Dec_GraphCreateConst1();
+    }
+
+    // perform CST
+    Mvc_CoverInverse( pCover ); // CST
+    // start the factored form
+    pFForm = Dec_GraphCreate( Abc_SopGetVarNum(pSop) );
+    // factor the cover
+    eRoot = Dec_Factor_rec( pFForm, pCover );
+    // finalize the factored form
+    Dec_GraphSetRoot( pFForm, eRoot );
+    // complement the factored form if SOP is complemented
+    if ( Abc_SopIsComplement(pSop) )
+        Dec_GraphComplement( pFForm );
+    // verify the factored form
+//    if ( !Dec_FactorVerify( pSop, pFForm ) )
+//        printf( "Verification has failed.\n" );
+//    Mvc_CoverInverse( pCover ); // undo CST
+    Mvc_CoverFree( pCover );
+    return pFForm;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Internal recursive factoring procedure.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Edge_t Dec_Factor_rec( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover )
+{
+    Mvc_Cover_t * pDiv, * pQuo, * pRem, * pCom;
+    Dec_Edge_t eNodeDiv, eNodeQuo, eNodeRem;
+    Dec_Edge_t eNodeAnd, eNode;
+
+    // make sure the cover contains some cubes
+    assert( Mvc_CoverReadCubeNum(pCover) );
+
+    // get the divisor
+    pDiv = Mvc_CoverDivisor( pCover );
+    if ( pDiv == NULL )
+        return Dec_FactorTrivial( pFForm, pCover );
+
+    // divide the cover by the divisor
+    Mvc_CoverDivideInternal( pCover, pDiv, &pQuo, &pRem );
+    assert( Mvc_CoverReadCubeNum(pQuo) );
+
+    Mvc_CoverFree( pDiv );
+    Mvc_CoverFree( pRem );
+
+    // check the trivial case
+    if ( Mvc_CoverReadCubeNum(pQuo) == 1 )
+    {
+        eNode = Dec_FactorLF_rec( pFForm, pCover, pQuo );
+        Mvc_CoverFree( pQuo );
+        return eNode;
+    }
+
+    // make the quotient cube free
+    Mvc_CoverMakeCubeFree( pQuo );
+
+    // divide the cover by the quotient
+    Mvc_CoverDivideInternal( pCover, pQuo, &pDiv, &pRem );
+
+    // check the trivial case
+    if ( Mvc_CoverIsCubeFree( pDiv ) )
+    {
+        eNodeDiv = Dec_Factor_rec( pFForm, pDiv );
+        eNodeQuo = Dec_Factor_rec( pFForm, pQuo );
+        Mvc_CoverFree( pDiv );
+        Mvc_CoverFree( pQuo );
+        eNodeAnd = Dec_GraphAddNodeAnd( pFForm, eNodeDiv, eNodeQuo );
+        if ( Mvc_CoverReadCubeNum(pRem) == 0 )
+        {
+            Mvc_CoverFree( pRem );
+            return eNodeAnd;
+        }
+        else
+        {
+            eNodeRem = Dec_Factor_rec( pFForm, pRem );
+            Mvc_CoverFree( pRem );
+            return Dec_GraphAddNodeOr( pFForm, eNodeAnd, eNodeRem );
+        }
+    }
+
+    // get the common cube
+    pCom = Mvc_CoverCommonCubeCover( pDiv );
+    Mvc_CoverFree( pDiv );
+    Mvc_CoverFree( pQuo );
+    Mvc_CoverFree( pRem );
+
+    // solve the simple problem
+    eNode = Dec_FactorLF_rec( pFForm, pCover, pCom );
+    Mvc_CoverFree( pCom );
+    return eNode;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Internal recursive factoring procedure for the leaf case.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Edge_t Dec_FactorLF_rec( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover, Mvc_Cover_t * pSimple )
+{
+    Dec_Man_t * pManDec = Abc_FrameReadManDec();
+    Vec_Int_t * vEdgeLits  = pManDec->vLits;
+    Mvc_Cover_t * pDiv, * pQuo, * pRem;
+    Dec_Edge_t eNodeDiv, eNodeQuo, eNodeRem;
+    Dec_Edge_t eNodeAnd;
+
+    // get the most often occurring literal
+    pDiv = Mvc_CoverBestLiteralCover( pCover, pSimple );
+    // divide the cover by the literal
+    Mvc_CoverDivideByLiteral( pCover, pDiv, &pQuo, &pRem );
+    // get the node pointer for the literal
+    eNodeDiv = Dec_FactorTrivialCube( pFForm, pDiv, Mvc_CoverReadCubeHead(pDiv), vEdgeLits );
+    Mvc_CoverFree( pDiv );
+    // factor the quotient and remainder
+    eNodeQuo = Dec_Factor_rec( pFForm, pQuo );
+    Mvc_CoverFree( pQuo );
+    eNodeAnd = Dec_GraphAddNodeAnd( pFForm, eNodeDiv, eNodeQuo );
+    if ( Mvc_CoverReadCubeNum(pRem) == 0 )
+    {
+        Mvc_CoverFree( pRem );
+        return eNodeAnd;
+    }
+    else
+    {
+        eNodeRem = Dec_Factor_rec( pFForm, pRem );
+        Mvc_CoverFree( pRem );
+        return Dec_GraphAddNodeOr( pFForm,  eNodeAnd, eNodeRem );
+    }
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Factoring the cover, which has no algebraic divisors.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Edge_t Dec_FactorTrivial( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover )
+{
+    Dec_Man_t * pManDec = Abc_FrameReadManDec();
+    Vec_Int_t * vEdgeCubes = pManDec->vCubes;
+    Vec_Int_t * vEdgeLits  = pManDec->vLits;
+    Mvc_Manager_t * pMem = pManDec->pMvcMem;
+    Dec_Edge_t eNode;
+    Mvc_Cube_t * pCube;
+    // create the factored form for each cube
+    Vec_IntClear( vEdgeCubes );
+    Mvc_CoverForEachCube( pCover, pCube )
+    {
+        eNode = Dec_FactorTrivialCube( pFForm, pCover, pCube, vEdgeLits );
+        Vec_IntPush( vEdgeCubes, Dec_EdgeToInt_(eNode) );
+    }
+    // balance the factored forms
+    return Dec_FactorTrivialTree_rec( pFForm, (Dec_Edge_t *)vEdgeCubes->pArray, vEdgeCubes->nSize, 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Factoring the cube.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Edge_t Dec_FactorTrivialCube( Dec_Graph_t * pFForm, Mvc_Cover_t * pCover, Mvc_Cube_t * pCube, Vec_Int_t * vEdgeLits )
+{
+    Dec_Edge_t eNode;
+    int iBit, Value;
+    // create the factored form for each literal
+    Vec_IntClear( vEdgeLits );
+    Mvc_CubeForEachBit( pCover, pCube, iBit, Value )
+        if ( Value )
+        {
+            eNode = Dec_EdgeCreate( iBit/2, iBit%2 ); // CST
+            Vec_IntPush( vEdgeLits, Dec_EdgeToInt_(eNode) );
+        }
+    // balance the factored forms
+    return Dec_FactorTrivialTree_rec( pFForm, (Dec_Edge_t *)vEdgeLits->pArray, vEdgeLits->nSize, 0 );
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    [Create the well-balanced tree of nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Edge_t Dec_FactorTrivialTree_rec( Dec_Graph_t * pFForm, Dec_Edge_t * peNodes, int nNodes, int fNodeOr )
+{
+    Dec_Edge_t eNode1, eNode2;
+    int nNodes1, nNodes2;
+
+    if ( nNodes == 1 )
+        return peNodes[0];
+
+    // split the nodes into two parts
+    nNodes1 = nNodes/2;
+    nNodes2 = nNodes - nNodes1;
+//    nNodes2 = nNodes/2;
+//    nNodes1 = nNodes - nNodes2;
+
+    // recursively construct the tree for the parts
+    eNode1 = Dec_FactorTrivialTree_rec( pFForm, peNodes,           nNodes1, fNodeOr );
+    eNode2 = Dec_FactorTrivialTree_rec( pFForm, peNodes + nNodes1, nNodes2, fNodeOr );
+
+    if ( fNodeOr )
+        return Dec_GraphAddNodeOr( pFForm, eNode1, eNode2 );
+    else
+        return Dec_GraphAddNodeAnd( pFForm, eNode1, eNode2 );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Converts SOP into MVC.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Mvc_Cover_t * Dec_ConvertSopToMvc( char * pSop )
+{
+    Dec_Man_t * pManDec = Abc_FrameReadManDec();
+    Mvc_Manager_t * pMem = pManDec->pMvcMem;
+    Mvc_Cover_t * pMvc;
+    Mvc_Cube_t * pMvcCube;
+    char * pCube;
+    int nVars, Value, v;
+
+    // start the cover
+    nVars = Abc_SopGetVarNum(pSop);
+    pMvc = Mvc_CoverAlloc( pMem, nVars * 2 );
+    // check the logic function of the node
+    Abc_SopForEachCube( pSop, nVars, pCube )
+    {
+        // create and add the cube
+        pMvcCube = Mvc_CubeAlloc( pMvc );
+        Mvc_CoverAddCubeTail( pMvc, pMvcCube );
+        // fill in the literals
+        Mvc_CubeBitFill( pMvcCube );
+        Abc_CubeForEachVar( pCube, Value, v )
+        {
+            if ( Value == '0' )
+                Mvc_CubeBitRemove( pMvcCube, v * 2 + 1 );
+            else if ( Value == '1' )
+                Mvc_CubeBitRemove( pMvcCube, v * 2 );
+        }
+    }
+    return pMvc;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies that the factoring is correct.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Dec_FactorVerify( char * pSop, Dec_Graph_t * pFForm )
+{
+    DdManager * dd = Abc_FrameReadManDd();
+    DdNode * bFunc1, * bFunc2;
+    int RetValue;
+    bFunc1 = Abc_ConvertSopToBdd( dd, pSop );    Cudd_Ref( bFunc1 );
+    bFunc2 = Dec_GraphDeriveBdd( dd, pFForm );   Cudd_Ref( bFunc2 );
+//Extra_bddPrint( dd, bFunc1 ); printf("\n");
+//Extra_bddPrint( dd, bFunc2 ); printf("\n");
+    RetValue = (bFunc1 == bFunc2);
+    if ( bFunc1 != bFunc2 )
+    {
+        int s;
+        Extra_bddPrint( dd, bFunc1 ); printf("\n");
+        Extra_bddPrint( dd, bFunc2 ); printf("\n");
+        s  = 0;
+    }
+    Cudd_RecursiveDeref( dd, bFunc1 );
+    Cudd_RecursiveDeref( dd, bFunc2 );
+    return RetValue;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/dec/decMan.c b/src/opt/dec/decMan.c
new file mode 100644
index 00000000..65857461
--- /dev/null
+++ b/src/opt/dec/decMan.c
@@ -0,0 +1,83 @@
+/**CFile****************************************************************
+
+  FileName    [decMan.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Decomposition manager.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: decMan.c,v 1.1 2003/05/22 19:20:05 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "mvc.h"
+#include "dec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Start the MVC manager used in the factoring package.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Man_t * Dec_ManStart()
+{
+    Dec_Man_t * p;
+    int clk = clock();
+    p = ALLOC( Dec_Man_t, 1 );
+    p->pMvcMem = Mvc_ManagerStart();
+    p->vCubes = Vec_IntAlloc( 8 );
+    p->vLits = Vec_IntAlloc( 8 );
+    // canonical forms, phases, perms
+    Extra_Truth4VarNPN( &p->puCanons, &p->pPhases, &p->pPerms, &p->pMap );
+//PRT( "NPN classes precomputation time", clock() - clk ); 
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the MVC maanager used in the factoring package.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Dec_ManStop( Dec_Man_t * p )
+{
+    Mvc_ManagerFree( p->pMvcMem );
+    Vec_IntFree( p->vCubes );
+    Vec_IntFree( p->vLits );
+    free( p->puCanons );
+    free( p->pPhases );
+    free( p->pPerms );
+    free( p->pMap );
+    free( p );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/dec/decPrint.c b/src/opt/dec/decPrint.c
new file mode 100644
index 00000000..2d8f09b3
--- /dev/null
+++ b/src/opt/dec/decPrint.c
@@ -0,0 +1,284 @@
+/**CFile****************************************************************
+
+  FileName    [decPrint.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Procedures to print the decomposition graphs (factored forms).]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: decPrint.c,v 1.1 2003/05/22 19:20:05 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "dec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void   Dec_GraphPrint_rec( FILE * pFile, Dec_Graph_t * pGraph, Dec_Node_t * pNode, int fCompl, char * pNamesIn[], int * pPos, int LitSizeMax );
+static int    Dec_GraphPrintGetLeafName( FILE * pFile, int iLeaf, int fCompl, char * pNamesIn[] );
+static void   Dec_GraphPrintUpdatePos( FILE * pFile, int * pPos, int LitSizeMax );
+static int    Dec_GraphPrintOutputName( FILE * pFile, char * pNameOut, int fCompl );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the decomposition graph.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Dec_GraphPrint( FILE * pFile, Dec_Graph_t * pGraph, char * pNamesIn[], char * pNameOut )
+{
+    Vec_Ptr_t * vNamesIn = NULL;
+    int LitSizeMax, LitSizeCur, Pos, i;
+
+    // create the names if not given by the user
+    if ( pNamesIn == NULL )
+    {
+        vNamesIn = Abc_NodeGetFakeNames( Dec_GraphLeaveNum(pGraph) );
+        pNamesIn = (char **)vNamesIn->pArray;
+    }
+    if ( pNameOut == NULL )
+        pNameOut = "F";
+
+    // get the size of the longest literal
+    LitSizeMax = 0;
+    for ( i = 0; i < Dec_GraphLeaveNum(pGraph); i++ )
+    {
+        LitSizeCur = strlen(pNamesIn[i]);
+        if ( LitSizeMax < LitSizeCur )
+            LitSizeMax = LitSizeCur;
+    }
+    if ( LitSizeMax > 50 )
+        LitSizeMax = 20;
+
+    // write the decomposition graph (factored form)
+    if ( Dec_GraphIsConst(pGraph) ) // constant
+    {
+        Pos = Dec_GraphPrintOutputName( pFile, pNameOut, 0 );
+        fprintf( pFile, "Constant %d", !Dec_GraphIsComplement(pGraph) );
+    }
+    else if ( Dec_GraphIsVar(pGraph) ) // literal
+    {
+        Pos = Dec_GraphPrintOutputName( pFile, pNameOut, 0 );
+        Dec_GraphPrintGetLeafName( pFile, Dec_GraphVarInt(pGraph), Dec_GraphIsComplement(pGraph), pNamesIn );
+    }
+    else
+    {
+        Pos = Dec_GraphPrintOutputName( pFile, pNameOut, Dec_GraphIsComplement(pGraph) );
+        Dec_GraphPrint_rec( pFile, pGraph, Dec_GraphNodeLast(pGraph), 0, pNamesIn, &Pos, LitSizeMax );
+    }
+    fprintf( pFile, "\n" );
+
+    if ( vNamesIn )
+        Abc_NodeFreeNames( vNamesIn );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Dec_GraphPrint2_rec( FILE * pFile, Dec_Graph_t * pGraph, Dec_Node_t * pNode, int fCompl, char * pNamesIn[], int * pPos, int LitSizeMax )
+{
+    Dec_Node_t * pNode0, * pNode1;
+    pNode0 = Dec_GraphNode(pGraph, pNode->eEdge0.Node);
+    pNode1 = Dec_GraphNode(pGraph, pNode->eEdge1.Node);
+    if ( Dec_GraphNodeIsVar(pGraph, pNode) ) // FT_NODE_LEAF )
+    {
+        (*pPos) += Dec_GraphPrintGetLeafName( pFile, Dec_GraphNodeInt(pGraph,pNode), fCompl, pNamesIn );
+        return;
+    }
+    if ( !pNode->fNodeOr ) // FT_NODE_AND )
+    {
+        if ( !pNode0->fNodeOr ) // != FT_NODE_OR )
+            Dec_GraphPrint_rec( pFile, pGraph, pNode0, pNode->fCompl0, pNamesIn, pPos, LitSizeMax );
+        else
+        {
+            fprintf( pFile, "(" );
+            (*pPos)++;
+            Dec_GraphPrint_rec( pFile, pGraph, pNode0, pNode->fCompl0, pNamesIn, pPos, LitSizeMax );
+            fprintf( pFile, ")" );
+            (*pPos)++;
+        }
+        fprintf( pFile, " " );
+        (*pPos)++;
+
+        Dec_GraphPrintUpdatePos( pFile, pPos, LitSizeMax );
+
+        if ( !pNode1->fNodeOr ) // != FT_NODE_OR )
+            Dec_GraphPrint_rec( pFile, pGraph, pNode1, pNode->fCompl1, pNamesIn, pPos, LitSizeMax );
+        else
+        {
+            fprintf( pFile, "(" );
+            (*pPos)++;
+            Dec_GraphPrint_rec( pFile, pGraph, pNode1, pNode->fCompl1, pNamesIn, pPos, LitSizeMax );
+            fprintf( pFile, ")" );
+            (*pPos)++;
+        }
+        return;
+    }
+    if ( pNode->fNodeOr ) // FT_NODE_OR )
+    {
+        Dec_GraphPrint_rec( pFile, pGraph, pNode0, pNode->fCompl0, pNamesIn, pPos, LitSizeMax );
+        fprintf( pFile, " + " );
+        (*pPos) += 3;
+
+        Dec_GraphPrintUpdatePos( pFile, pPos, LitSizeMax );
+
+        Dec_GraphPrint_rec( pFile, pGraph, pNode1, pNode->fCompl1, pNamesIn, pPos, LitSizeMax );
+        return;
+    }
+    assert( 0 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Dec_GraphPrint_rec( FILE * pFile, Dec_Graph_t * pGraph, Dec_Node_t * pNode, int fCompl, char * pNamesIn[], int * pPos, int LitSizeMax )
+{
+    Dec_Node_t * pNode0, * pNode1;
+    Dec_Node_t * pNode00, * pNode01, * pNode10, * pNode11;
+    pNode0 = Dec_GraphNode(pGraph, pNode->eEdge0.Node);
+    pNode1 = Dec_GraphNode(pGraph, pNode->eEdge1.Node);
+    if ( Dec_GraphNodeIsVar(pGraph, pNode) ) // FT_NODE_LEAF )
+    {
+        (*pPos) += Dec_GraphPrintGetLeafName( pFile, Dec_GraphNodeInt(pGraph,pNode), fCompl, pNamesIn );
+        return;
+    }
+    if ( !Dec_GraphNodeIsVar(pGraph, pNode0) && !Dec_GraphNodeIsVar(pGraph, pNode1) )
+    {
+        pNode00 = Dec_GraphNode(pGraph, pNode0->eEdge0.Node);
+        pNode01 = Dec_GraphNode(pGraph, pNode0->eEdge1.Node);
+        pNode10 = Dec_GraphNode(pGraph, pNode1->eEdge0.Node);
+        pNode11 = Dec_GraphNode(pGraph, pNode1->eEdge1.Node);
+        if ( (pNode00 == pNode10 || pNode00 == pNode11) && (pNode01 == pNode10 || pNode01 == pNode11) )
+        {
+            fprintf( pFile, "(" );
+            (*pPos)++;
+            Dec_GraphPrint_rec( pFile, pGraph, pNode00, pNode00->fCompl0, pNamesIn, pPos, LitSizeMax );
+            fprintf( pFile, " # " );
+            (*pPos) += 3;
+            Dec_GraphPrint_rec( pFile, pGraph, pNode01, pNode01->fCompl1, pNamesIn, pPos, LitSizeMax );
+            fprintf( pFile, ")" );
+            (*pPos)++;
+            return;
+        }
+    }
+    if ( fCompl )
+    {
+        fprintf( pFile, "(" );
+        (*pPos)++;
+        Dec_GraphPrint_rec( pFile, pGraph, pNode0, !pNode->fCompl0, pNamesIn, pPos, LitSizeMax );
+        fprintf( pFile, " + " );
+        (*pPos) += 3;
+        Dec_GraphPrint_rec( pFile, pGraph, pNode1, !pNode->fCompl1, pNamesIn, pPos, LitSizeMax );
+        fprintf( pFile, ")" );
+        (*pPos)++;
+    }
+    else
+    {
+        fprintf( pFile, "(" );
+        (*pPos)++;
+        Dec_GraphPrint_rec( pFile, pGraph, pNode0, pNode->fCompl0, pNamesIn, pPos, LitSizeMax );
+        Dec_GraphPrint_rec( pFile, pGraph, pNode1, pNode->fCompl1, pNamesIn, pPos, LitSizeMax );
+        fprintf( pFile, ")" );
+        (*pPos)++;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Dec_GraphPrintGetLeafName( FILE * pFile, int iLeaf, int fCompl, char * pNamesIn[] )
+{
+    static char Buffer[100];
+    sprintf( Buffer, "%s%s", pNamesIn[iLeaf], fCompl? "\'" : "" );
+    fprintf( pFile, "%s", Buffer );
+    return strlen( Buffer );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Dec_GraphPrintUpdatePos( FILE * pFile, int * pPos, int LitSizeMax )
+{
+    int i;
+    if ( *pPos + LitSizeMax < 77 )
+        return;
+    fprintf( pFile, "\n" );
+    for ( i = 0; i < 10; i++ )
+        fprintf( pFile, " " );
+    *pPos = 10;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the printout for a decomposition graph.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Dec_GraphPrintOutputName( FILE * pFile, char * pNameOut, int fCompl )
+{
+    if ( pNameOut == NULL )
+        return 0;
+    fprintf( pFile, "%6s%s = ", pNameOut, fCompl? "\'" : " " );
+    return 10;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/dec/decUtil.c b/src/opt/dec/decUtil.c
new file mode 100644
index 00000000..463bc7e2
--- /dev/null
+++ b/src/opt/dec/decUtil.c
@@ -0,0 +1,134 @@
+/**CFile****************************************************************
+
+  FileName    [decUtil.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Decomposition unitilies.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: decUtil.c,v 1.1 2003/05/22 19:20:05 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "dec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Converts graph to BDD.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+DdNode * Dec_GraphDeriveBdd( DdManager * dd, Dec_Graph_t * pGraph )
+{
+    DdNode * bFunc, * bFunc0, * bFunc1;
+    Dec_Node_t * pNode;
+    int i;
+
+    // sanity checks
+    assert( Dec_GraphLeaveNum(pGraph) >= 0 );
+    assert( Dec_GraphLeaveNum(pGraph) <= pGraph->nSize );
+
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Cudd_NotCond( b1, Dec_GraphIsComplement(pGraph) );
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+        return Cudd_NotCond( Cudd_bddIthVar(dd, Dec_GraphVarInt(pGraph)), Dec_GraphIsComplement(pGraph) );
+
+    // assign the elementary variables
+    Dec_GraphForEachLeaf( pGraph, pNode, i )
+        pNode->pFunc = Cudd_bddIthVar( dd, i );
+
+    // compute the function for each internal node
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        bFunc0 = Cudd_NotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
+        bFunc1 = Cudd_NotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
+        pNode->pFunc = Cudd_bddAnd( dd, bFunc0, bFunc1 );   Cudd_Ref( pNode->pFunc );
+    }
+
+    // deref the intermediate results
+    bFunc = pNode->pFunc;   Cudd_Ref( bFunc );
+    Dec_GraphForEachNode( pGraph, pNode, i )
+        Cudd_RecursiveDeref( dd, pNode->pFunc );
+    Cudd_Deref( bFunc );
+
+    // complement the result if necessary
+    return Cudd_NotCond( bFunc, Dec_GraphIsComplement(pGraph) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Derives the truth table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Dec_GraphDeriveTruth( Dec_Graph_t * pGraph )
+{
+    unsigned uTruths[5] = { 0xAAAAAAAA, 0xCCCCCCCC, 0xF0F0F0F0, 0xFF00FF00, 0xFFFF0000 };
+    unsigned uTruth, uTruth0, uTruth1;
+    Dec_Node_t * pNode;
+    int i;
+
+    // sanity checks
+    assert( Dec_GraphLeaveNum(pGraph) >= 0 );
+    assert( Dec_GraphLeaveNum(pGraph) <= pGraph->nSize );
+    assert( Dec_GraphLeaveNum(pGraph) <= 5 );
+
+    // check for constant function
+    if ( Dec_GraphIsConst(pGraph) )
+        return Dec_GraphIsComplement(pGraph)? 0 : ~((unsigned)0);
+    // check for a literal
+    if ( Dec_GraphIsVar(pGraph) )
+        return Dec_GraphIsComplement(pGraph)? ~uTruths[Dec_GraphVarInt(pGraph)] : uTruths[Dec_GraphVarInt(pGraph)];
+
+    // assign the elementary variables
+    Dec_GraphForEachLeaf( pGraph, pNode, i )
+        pNode->pFunc = (void *)uTruths[i];
+
+    // compute the function for each internal node
+    Dec_GraphForEachNode( pGraph, pNode, i )
+    {
+        uTruth0 = (unsigned)Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc;
+        uTruth1 = (unsigned)Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc;
+        uTruth0 = pNode->eEdge0.fCompl? ~uTruth0 : uTruth0;
+        uTruth1 = pNode->eEdge1.fCompl? ~uTruth1 : uTruth1;
+        uTruth = uTruth0 & uTruth1;
+        pNode->pFunc = (void *)uTruth;
+    }
+
+    // complement the result if necessary
+    return Dec_GraphIsComplement(pGraph)? ~uTruth : uTruth;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/dec/module.make b/src/opt/dec/module.make
new file mode 100644
index 00000000..1e0722d5
--- /dev/null
+++ b/src/opt/dec/module.make
@@ -0,0 +1,5 @@
+SRC +=  src/opt/dec/decAbc.c \
+        src/opt/dec/decFactor.c \
+        src/opt/dec/decMan.c \
+        src/opt/dec/decPrint.c \
+        src/opt/dec/decUtil.c 
diff --git a/src/opt/fxu/fxu.c b/src/opt/fxu/fxu.c
new file mode 100644
index 00000000..d11fd793
--- /dev/null
+++ b/src/opt/fxu/fxu.c
@@ -0,0 +1,254 @@
+/**CFile****************************************************************
+
+  FileName    [fxu.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [The entrance into the fast extract module.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxu.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h" 
+#include "fxu.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+/*===== fxuCreate.c ====================================================*/
+extern Fxu_Matrix * Fxu_CreateMatrix( Fxu_Data_t * pData );
+extern void         Fxu_CreateCovers( Fxu_Matrix * p, Fxu_Data_t * pData );
+
+static int s_MemoryTotal;
+static int s_MemoryPeak;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs fast_extract on a set of covers.]
+
+  Description [All the covers are given in the array p->vSops. 
+  The resulting covers are returned in the array p->vSopsNew.
+  The entries in these arrays correspond to objects in the network.
+  The entries corresponding to the PI and objects with trivial covers are NULL.
+  The number of extracted covers (not exceeding p->nNodesExt) is returned. 
+  Two other things are important for the correct operation of this procedure:
+  (1) The input covers do not have duplicated fanins and are SCC-free. 
+  (2) The fanins array contains the numbers of the fanin objects.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_FastExtract( Fxu_Data_t * pData )
+{
+    Fxu_Matrix * p;
+    Fxu_Single * pSingle;
+    Fxu_Double * pDouble;
+    int Weight1, Weight2, Weight3;
+    int Counter = 0;
+
+    s_MemoryTotal = 0;
+    s_MemoryPeak  = 0;
+
+    // create the matrix
+    p = Fxu_CreateMatrix( pData );
+    if ( p == NULL )
+        return -1;
+//    if ( pData->fVerbose )
+//        printf( "Memory usage after construction: Total = %d. Peak = %d.\n", s_MemoryTotal, s_MemoryPeak );
+//Fxu_MatrixPrint( NULL, p );
+
+    if ( pData->fOnlyS )
+    {
+        pData->nNodesNew = 0;
+        do
+        {
+            Weight1 = Fxu_HeapSingleReadMaxWeight( p->pHeapSingle );
+            if ( pData->fVerbose )
+                printf( "Div %5d : Best single = %5d.\r", Counter++, Weight1 );
+            if ( Weight1 > 0 || Weight1 == 0 && pData->fUse0 )
+                Fxu_UpdateSingle( p );
+            else
+                break;
+        }
+        while ( ++pData->nNodesNew < pData->nNodesExt );
+    }
+    else if ( pData->fOnlyD )
+    {
+        pData->nNodesNew = 0;
+        do
+        {
+            Weight2 = Fxu_HeapDoubleReadMaxWeight( p->pHeapDouble );
+            if ( pData->fVerbose )
+                printf( "Div %5d : Best double = %5d.\r", Counter++, Weight2 );
+            if ( Weight2 > 0 || Weight2 == 0 && pData->fUse0 )
+                Fxu_UpdateDouble( p );
+            else
+                break;
+        }
+        while ( ++pData->nNodesNew < pData->nNodesExt );
+    }
+    else if ( !pData->fUseCompl )
+    {
+        pData->nNodesNew = 0;
+        do
+        {
+            Weight1 = Fxu_HeapSingleReadMaxWeight( p->pHeapSingle );
+            Weight2 = Fxu_HeapDoubleReadMaxWeight( p->pHeapDouble );
+
+            if ( pData->fVerbose )
+                printf( "Div %5d : Best double = %5d. Best single = %5d.\r", Counter++, Weight2, Weight1 );
+//Fxu_Select( p, &pSingle, &pDouble );
+
+            if ( Weight1 >= Weight2 )
+            {
+                if ( Weight1 > 0 || Weight1 == 0 && pData->fUse0 )
+                    Fxu_UpdateSingle( p );
+                else
+                    break;
+            }
+            else
+            {
+                if ( Weight2 > 0 || Weight2 == 0 && pData->fUse0 )
+                    Fxu_UpdateDouble( p );
+                else
+                    break;
+            }
+        }
+        while ( ++pData->nNodesNew < pData->nNodesExt );
+    }
+    else
+    { // use the complement
+        pData->nNodesNew = 0;
+        do
+        {
+            Weight1 = Fxu_HeapSingleReadMaxWeight( p->pHeapSingle );
+            Weight2 = Fxu_HeapDoubleReadMaxWeight( p->pHeapDouble );
+
+            // select the best single and double
+            Weight3 = Fxu_Select( p, &pSingle, &pDouble );
+            if ( pData->fVerbose )
+                printf( "Div %5d : Best double = %5d. Best single = %5d. Best complement = %5d.\r", 
+                    Counter++, Weight2, Weight1, Weight3 );
+
+            if ( Weight3 > 0 || Weight3 == 0 && pData->fUse0 )
+                Fxu_Update( p, pSingle, pDouble );
+            else
+                break;
+        }
+        while ( ++pData->nNodesNew < pData->nNodesExt );
+    }
+
+    if ( pData->fVerbose )
+        printf( "Total single = %3d. Total double = %3d. Total compl = %3d.                    \n", 
+        p->nDivs1, p->nDivs2, p->nDivs3 );
+
+    // create the new covers
+    if ( pData->nNodesNew )
+        Fxu_CreateCovers( p, pData );
+    Fxu_MatrixDelete( p );
+//    printf( "Memory usage after deallocation:   Total = %d. Peak = %d.\n", s_MemoryTotal, s_MemoryPeak );
+    if ( pData->nNodesNew == pData->nNodesExt )
+        printf( "Warning: The limit on the number of extracted divisors has been reached.\n" );
+    return pData->nNodesNew;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Unmarks the cubes in the ring.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixRingCubesUnmark( Fxu_Matrix * p )
+{
+    Fxu_Cube * pCube, * pCube2;
+    // unmark the cubes
+    Fxu_MatrixForEachCubeInRingSafe( p, pCube, pCube2 )
+        pCube->pOrder = NULL;
+    Fxu_MatrixRingCubesReset( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Unmarks the vars in the ring.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixRingVarsUnmark( Fxu_Matrix * p )
+{
+    Fxu_Var * pVar, * pVar2;
+    // unmark the vars
+    Fxu_MatrixForEachVarInRingSafe( p, pVar, pVar2 )
+        pVar->pOrder = NULL;
+    Fxu_MatrixRingVarsReset( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+char * Fxu_MemFetch( Fxu_Matrix * p, int nBytes )
+{
+    s_MemoryTotal += nBytes;
+    if ( s_MemoryPeak < s_MemoryTotal )
+        s_MemoryPeak = s_MemoryTotal;
+//    return malloc( nBytes );
+    return Extra_MmFixedEntryFetch( p->pMemMan );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MemRecycle( Fxu_Matrix * p, char * pItem, int nBytes )
+{
+    s_MemoryTotal -= nBytes;
+//    free( pItem );
+    Extra_MmFixedEntryRecycle( p->pMemMan, pItem );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxu.h b/src/opt/fxu/fxu.h
new file mode 100644
index 00000000..e6d0b69e
--- /dev/null
+++ b/src/opt/fxu/fxu.h
@@ -0,0 +1,93 @@
+/**CFile****************************************************************
+
+  FileName    [fxu.h]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [External declarations of fast extract for unate covers.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxu.h,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#ifndef __FXU_H__
+#define __FXU_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "vec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    STRUCTURE DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+#ifndef __cplusplus
+#ifndef bool
+#define bool int
+#endif
+#endif
+
+typedef struct FxuDataStruct   Fxu_Data_t;
+
+// structure for the FX input/output data 
+struct FxuDataStruct
+{
+    // user specified parameters
+    bool              fOnlyS;           // set to 1 to have only single-cube divs
+    bool              fOnlyD;           // set to 1 to have only double-cube divs
+    bool              fUse0;            // set to 1 to have 0-weight also extracted
+    bool              fUseCompl;        // set to 1 to have complement taken into account
+    bool              fVerbose;         // set to 1 to have verbose output
+    int               nNodesExt;        // the number of divisors to extract
+    int               nSingleMax;       // the max number of single-cube divisors to consider
+    int               nPairsMax;        // the max number of double-cube divisors to consider
+    // the input information
+    Vec_Ptr_t *       vSops;            // the SOPs for each node in the network
+    Vec_Ptr_t *       vFanins;          // the fanins of each node in the network
+    // output information
+    Vec_Ptr_t *       vSopsNew;         // the SOPs for each node in the network after extraction
+    Vec_Ptr_t *       vFaninsNew;       // the fanins of each node in the network after extraction
+    // the SOP manager
+    Extra_MmFlex_t *  pManSop;
+    // statistics   
+    int               nNodesOld;        // the old number of nodes
+    int               nNodesNew;        // the number of divisors actually extracted
+};
+
+////////////////////////////////////////////////////////////////////////
+///                       MACRO DEFINITIONS                          ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*===== fxu.c ==========================================================*/
+extern int          Fxu_FastExtract( Fxu_Data_t * pData );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/fxu/fxuCreate.c b/src/opt/fxu/fxuCreate.c
new file mode 100644
index 00000000..55026b27
--- /dev/null
+++ b/src/opt/fxu/fxuCreate.c
@@ -0,0 +1,431 @@
+/**CFile****************************************************************
+
+  FileName    [fxuCreate.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Create matrix from covers and covers from matrix.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuCreate.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "fxuInt.h"
+#include "fxu.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void        Fxu_CreateMatrixAddCube( Fxu_Matrix * p, Fxu_Cube * pCube, char * pSopCube, Vec_Int_t * vFanins, int * pOrder );
+static int         Fxu_CreateMatrixLitCompare( int * ptrX, int * ptrY );
+static void        Fxu_CreateCoversNode( Fxu_Matrix * p, Fxu_Data_t * pData, int iNode, Fxu_Cube * pCubeFirst, Fxu_Cube * pCubeNext );
+static Fxu_Cube *  Fxu_CreateCoversFirstCube( Fxu_Matrix * p, Fxu_Data_t * pData, int iNode );
+static int * s_pLits;
+
+extern int         Fxu_PreprocessCubePairs( Fxu_Matrix * p, Vec_Ptr_t * vCovers, int nPairsTotal, int nPairsMax );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the sparse matrix from the array of SOPs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Matrix * Fxu_CreateMatrix( Fxu_Data_t * pData )
+{
+    Fxu_Matrix * p;
+    Fxu_Var * pVar;
+    Fxu_Cube * pCubeFirst, * pCubeNew;
+    Fxu_Cube * pCube1, * pCube2;
+    Vec_Int_t * vFanins;
+    char * pSopCover;
+    char * pSopCube;
+    int * pOrder, nBitsMax;
+    int i, v, c;
+    int nCubesTotal;
+    int nPairsTotal;
+    int nPairsStore;
+    int nCubes;
+    int iCube, iPair;
+    int nFanins;
+
+    // collect all sorts of statistics
+    nCubesTotal =  0;
+    nPairsTotal =  0;
+    nPairsStore =  0;
+    nBitsMax    = -1; 
+    for ( i = 0; i < pData->nNodesOld; i++ )
+        if ( pSopCover = pData->vSops->pArray[i] )
+        {
+            nCubes       = Abc_SopGetCubeNum( pSopCover );
+            nFanins      = Abc_SopGetVarNum( pSopCover );
+            assert( nFanins > 1 && nCubes > 0 );
+
+            nCubesTotal += nCubes;
+            nPairsTotal += nCubes * (nCubes - 1) / 2;
+            nPairsStore += nCubes * nCubes;
+            if ( nBitsMax < nFanins )
+                nBitsMax = nFanins;
+        }
+    if ( nBitsMax <= 0 )
+    {
+        printf( "The current network does not have SOPs to perform extraction.\n" );
+        return NULL;
+    }
+
+    if ( nPairsStore > 50000000 )
+    {
+        printf( "The problem is too large to be solved by \"fxu\" (%d cubes and %d cube pairs)\n", nCubesTotal, nPairsStore );
+        return NULL;
+    }
+
+    // start the matrix
+    p = Fxu_MatrixAllocate();
+    // create the column labels 
+    p->ppVars = ALLOC( Fxu_Var *, 2 * (pData->nNodesOld + pData->nNodesExt) );
+    for ( i = 0; i < 2 * pData->nNodesOld; i++ )
+        p->ppVars[i] = Fxu_MatrixAddVar( p );
+
+    // allocate storage for all cube pairs at once
+    p->pppPairs = ALLOC( Fxu_Pair **, nCubesTotal + 100 );
+    p->ppPairs  = ALLOC( Fxu_Pair *,  nPairsStore + 100 );
+    memset( p->ppPairs, 0, sizeof(Fxu_Pair *) * nPairsStore );
+    iCube = 0;
+    iPair = 0;
+    for ( i = 0; i < pData->nNodesOld; i++ )
+        if ( pSopCover = pData->vSops->pArray[i] )
+        {
+            // get the number of cubes
+            nCubes = Abc_SopGetCubeNum( pSopCover );
+            // get the new var in the matrix
+            pVar = p->ppVars[2*i+1];
+            // assign the pair storage
+            pVar->nCubes     = nCubes;
+            if ( nCubes > 0 )
+            {
+                pVar->ppPairs    = p->pppPairs + iCube;
+                pVar->ppPairs[0] = p->ppPairs  + iPair;
+                for ( v = 1; v < nCubes; v++ )
+                    pVar->ppPairs[v] = pVar->ppPairs[v-1] + nCubes;
+            }
+            // update
+            iCube += nCubes;
+            iPair += nCubes * nCubes;
+        }
+    assert( iCube == nCubesTotal );
+    assert( iPair == nPairsStore );
+
+
+    // allocate room for the reordered literals
+    pOrder = ALLOC( int, nBitsMax );
+    // create the rows
+    for ( i = 0; i < pData->nNodesOld; i++ )
+    if ( pSopCover = pData->vSops->pArray[i] )
+    {
+        // get the new var in the matrix
+        pVar = p->ppVars[2*i+1];
+        // here we sort the literals of the cover
+        // in the increasing order of the numbers of the corresponding nodes
+        // because literals should be added to the matrix in this order
+        vFanins = pData->vFanins->pArray[i];
+        s_pLits = vFanins->pArray;
+        // start the variable order
+        nFanins = Abc_SopGetVarNum( pSopCover );
+        for ( v = 0; v < nFanins; v++ )
+            pOrder[v] = v;
+        // reorder the fanins
+        qsort( (void *)pOrder, nFanins, sizeof(int),(int (*)(const void *, const void *))Fxu_CreateMatrixLitCompare);
+        assert( s_pLits[ pOrder[0] ] < s_pLits[ pOrder[nFanins-1] ] );
+        // create the corresponding cubes in the matrix
+        pCubeFirst = NULL;
+        c = 0;
+        Abc_SopForEachCube( pSopCover, nFanins, pSopCube )
+        {
+            // create the cube
+            pCubeNew = Fxu_MatrixAddCube( p, pVar, c++ );
+            Fxu_CreateMatrixAddCube( p, pCubeNew, pSopCube, vFanins, pOrder );
+            if ( pCubeFirst == NULL )
+                pCubeFirst = pCubeNew;
+            pCubeNew->pFirst = pCubeFirst;
+        }
+        // set the first cube of this var
+        pVar->pFirst = pCubeFirst;
+        // create the divisors without preprocessing
+        if ( nPairsTotal <= pData->nPairsMax )
+        {
+            for ( pCube1 = pCubeFirst; pCube1; pCube1 = pCube1->pNext )
+                for ( pCube2 = pCube1? pCube1->pNext: NULL; pCube2; pCube2 = pCube2->pNext )
+                    Fxu_MatrixAddDivisor( p, pCube1, pCube2 );
+        }
+    }
+    FREE( pOrder );
+
+    // consider the case when cube pairs should be preprocessed
+    // before adding them to the set of divisors
+//    if ( pData->fVerbose )
+//        printf( "The total number of cube pairs is %d.\n", nPairsTotal );
+    if ( nPairsTotal > 10000000 )
+    {
+        printf( "The total number of cube pairs of the network is more than 10,000,000.\n" );
+        printf( "Command \"fx\" takes a long time to run in such cases. It is suggested\n" );
+        printf( "that the user changes the network by reducing the size of logic node and\n" );
+        printf( "consequently the number of cube pairs to be processed by this command.\n" );
+        printf( "One way to achieve this is to run the commands \"st; multi -m -F <num>\"\n" );
+        printf( "as a proprocessing step, while selecting <num> as approapriate.\n" );
+        return NULL;
+    }
+    if ( nPairsTotal > pData->nPairsMax )
+        if ( !Fxu_PreprocessCubePairs( p, pData->vSops, nPairsTotal, pData->nPairsMax ) )
+            return NULL;
+//    if ( pData->fVerbose )
+//        printf( "Only %d best cube pairs will be used by the fast extract command.\n", pData->nPairsMax );
+
+    // add the var pairs to the heap
+    Fxu_MatrixComputeSingles( p, pData->fUse0, pData->nSingleMax );
+
+    // print stats
+    if ( pData->fVerbose )
+    {
+        double Density;
+        Density = ((double)p->nEntries) / p->lVars.nItems / p->lCubes.nItems;
+        fprintf( stdout, "Matrix: [vars x cubes] = [%d x %d]  ",
+            p->lVars.nItems, p->lCubes.nItems );
+        fprintf( stdout, "Lits = %d  Density = %.5f%%\n", 
+            p->nEntries, Density );
+        fprintf( stdout, "1-cube divs = %6d. (Total = %6d)  ",  p->lSingles.nItems, p->nSingleTotal );
+        fprintf( stdout, "2-cube divs = %6d. (Total = %6d)",  p->nDivsTotal, nPairsTotal );
+        fprintf( stdout, "\n" );
+    }
+//    Fxu_MatrixPrint( stdout, p );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one cube with literals to the matrix.]
+
+  Description [Create the cube and literals in the matrix corresponding 
+  to the given cube in the SOP cover. Co-singleton transform is performed here.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_CreateMatrixAddCube( Fxu_Matrix * p, Fxu_Cube * pCube, char * pSopCube, Vec_Int_t * vFanins, int * pOrder )
+{
+    Fxu_Var * pVar;
+    int Value, i;
+    // add literals to the matrix
+    Abc_CubeForEachVar( pSopCube, Value, i )
+    {
+        Value = pSopCube[pOrder[i]];
+        if ( Value == '0' )
+        {
+            pVar = p->ppVars[ 2 * vFanins->pArray[pOrder[i]] + 1 ];  // CST
+            Fxu_MatrixAddLiteral( p, pCube, pVar );
+        }
+        else if ( Value == '1' )
+        {
+            pVar = p->ppVars[ 2 * vFanins->pArray[pOrder[i]] ];  // CST
+            Fxu_MatrixAddLiteral( p, pCube, pVar );
+        }
+    }
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the new array of Sop covers from the sparse matrix.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_CreateCovers( Fxu_Matrix * p, Fxu_Data_t * pData )
+{
+    Fxu_Cube * pCube, * pCubeFirst, * pCubeNext;
+    char * pSopCover;
+    int iNode, n;
+
+    // get the first cube of the first internal node 
+    pCubeFirst = Fxu_CreateCoversFirstCube( p, pData, 0 );
+
+    // go through the internal nodes
+    for ( n = 0; n < pData->nNodesOld; n++ )
+    if ( pSopCover = pData->vSops->pArray[n] )
+    {
+        // get the number of this node
+        iNode = n;
+        // get the next first cube
+        pCubeNext = Fxu_CreateCoversFirstCube(  p, pData, iNode + 1 );
+        // check if there any new variables in these cubes
+        for ( pCube = pCubeFirst; pCube != pCubeNext; pCube = pCube->pNext )
+            if ( pCube->lLits.pTail && pCube->lLits.pTail->iVar >= 2 * pData->nNodesOld )
+                break;
+        if ( pCube != pCubeNext )
+            Fxu_CreateCoversNode( p, pData, iNode, pCubeFirst, pCubeNext );
+        // update the first cube
+        pCubeFirst = pCubeNext;
+    }
+
+    // add the covers for the extracted nodes
+    for ( n = 0; n < pData->nNodesNew; n++ )
+    {
+        // get the number of this node
+        iNode = pData->nNodesOld + n;
+        // get the next first cube
+        pCubeNext = Fxu_CreateCoversFirstCube( p, pData, iNode + 1 );
+        // the node should be added
+        Fxu_CreateCoversNode( p, pData, iNode, pCubeFirst, pCubeNext );
+        // update the first cube
+        pCubeFirst = pCubeNext;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Create Sop covers for one node that has changed.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_CreateCoversNode( Fxu_Matrix * p, Fxu_Data_t * pData, int iNode, Fxu_Cube * pCubeFirst, Fxu_Cube * pCubeNext )
+{
+    Vec_Int_t * vInputsNew;
+    char * pSopCover, * pSopCube;
+    Fxu_Var * pVar;
+    Fxu_Cube * pCube;
+    Fxu_Lit * pLit;
+    int iNum, nCubes, v;
+
+    // collect positive polarity variable in the cubes between pCubeFirst and pCubeNext
+    Fxu_MatrixRingVarsStart( p );
+    for ( pCube = pCubeFirst; pCube != pCubeNext; pCube = pCube->pNext )
+        for ( pLit = pCube->lLits.pHead; pLit; pLit = pLit->pHNext )
+        {
+            pVar = p->ppVars[ 2 * (pLit->pVar->iVar/2) + 1 ];
+            if ( pVar->pOrder == NULL )
+                Fxu_MatrixRingVarsAdd( p, pVar );
+        }
+    Fxu_MatrixRingVarsStop( p );
+
+    // collect the variable numbers
+    vInputsNew = Vec_IntAlloc( 4 );
+    Fxu_MatrixForEachVarInRing( p, pVar )
+        Vec_IntPush( vInputsNew, pVar->iVar / 2 );
+    Fxu_MatrixRingVarsUnmark( p );
+
+    // sort the vars by their number
+    Vec_IntSort( vInputsNew, 0 );
+
+    // mark the vars with their numbers in the sorted array
+    for ( v = 0; v < vInputsNew->nSize; v++ )
+    {
+        p->ppVars[ 2 * vInputsNew->pArray[v] + 0 ]->lLits.nItems = v; // hack - reuse lLits.nItems
+        p->ppVars[ 2 * vInputsNew->pArray[v] + 1 ]->lLits.nItems = v; // hack - reuse lLits.nItems
+    }
+
+    // count the number of cubes
+    nCubes = 0;
+    for ( pCube = pCubeFirst; pCube != pCubeNext; pCube = pCube->pNext )
+        if ( pCube->lLits.nItems )
+            nCubes++;
+
+    // allocate room for the new cover
+    pSopCover = Abc_SopStart( pData->pManSop, nCubes, vInputsNew->nSize );
+    // set the correct polarity of the cover
+    if ( iNode < pData->nNodesOld && Abc_SopGetPhase( pData->vSops->pArray[iNode] ) == 0 )
+        Abc_SopComplement( pSopCover );
+
+    // add the cubes
+    nCubes = 0;
+    for ( pCube = pCubeFirst; pCube != pCubeNext; pCube = pCube->pNext )
+    {
+        if ( pCube->lLits.nItems == 0 )
+            continue;
+        // get hold of the SOP cube
+        pSopCube = pSopCover + nCubes * (vInputsNew->nSize + 3);
+        // insert literals
+        for ( pLit = pCube->lLits.pHead; pLit; pLit = pLit->pHNext )
+        {
+            iNum = pLit->pVar->lLits.nItems; // hack - reuse lLits.nItems
+            assert( iNum < vInputsNew->nSize );
+            if ( pLit->pVar->iVar / 2 < pData->nNodesOld )
+                pSopCube[iNum] = (pLit->pVar->iVar & 1)? '0' : '1';   // reverse CST
+            else
+                pSopCube[iNum] = (pLit->pVar->iVar & 1)? '1' : '0';   // no CST
+        }
+        // count the cube
+        nCubes++;
+    }
+    assert( nCubes == Abc_SopGetCubeNum(pSopCover) );
+
+    // set the new cover and the array of fanins
+    pData->vSopsNew->pArray[iNode]   = pSopCover;
+    pData->vFaninsNew->pArray[iNode] = vInputsNew;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the var to storage.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Cube * Fxu_CreateCoversFirstCube( Fxu_Matrix * p, Fxu_Data_t * pData, int iVar )
+{
+    int v;
+    for ( v = iVar; v < pData->nNodesOld + pData->nNodesNew; v++ )
+        if ( p->ppVars[ 2*v + 1 ]->pFirst )
+            return p->ppVars[ 2*v + 1 ]->pFirst;
+    return NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compares the vars by their number.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_CreateMatrixLitCompare( int * ptrX, int * ptrY )
+{
+    return s_pLits[*ptrX] - s_pLits[*ptrY];
+} 
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
diff --git a/src/opt/fxu/fxuHeapD.c b/src/opt/fxu/fxuHeapD.c
new file mode 100644
index 00000000..c81ad818
--- /dev/null
+++ b/src/opt/fxu/fxuHeapD.c
@@ -0,0 +1,445 @@
+/**CFile****************************************************************
+
+  FileName    [fxuHeapD.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [The priority queue for double cube divisors.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuHeapD.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define FXU_HEAP_DOUBLE_WEIGHT(pDiv)           ((pDiv)->Weight)
+#define FXU_HEAP_DOUBLE_CURRENT(p, pDiv)       ((p)->pTree[(pDiv)->HNum])
+#define FXU_HEAP_DOUBLE_PARENT_EXISTS(p, pDiv) ((pDiv)->HNum > 1)
+#define FXU_HEAP_DOUBLE_CHILD1_EXISTS(p, pDiv) (((pDiv)->HNum << 1) <= p->nItems)
+#define FXU_HEAP_DOUBLE_CHILD2_EXISTS(p, pDiv) ((((pDiv)->HNum << 1)+1) <= p->nItems)
+#define FXU_HEAP_DOUBLE_PARENT(p, pDiv)        ((p)->pTree[(pDiv)->HNum >> 1])
+#define FXU_HEAP_DOUBLE_CHILD1(p, pDiv)        ((p)->pTree[(pDiv)->HNum << 1])
+#define FXU_HEAP_DOUBLE_CHILD2(p, pDiv)        ((p)->pTree[((pDiv)->HNum << 1)+1])
+#define FXU_HEAP_DOUBLE_ASSERT(p, pDiv)        assert( (pDiv)->HNum >= 1 && (pDiv)->HNum <= p->nItemsAlloc )
+
+static void Fxu_HeapDoubleResize( Fxu_HeapDouble * p );                  
+static void Fxu_HeapDoubleSwap( Fxu_Double ** pDiv1, Fxu_Double ** pDiv2 );  
+static void Fxu_HeapDoubleMoveUp( Fxu_HeapDouble * p, Fxu_Double * pDiv );  
+static void Fxu_HeapDoubleMoveDn( Fxu_HeapDouble * p, Fxu_Double * pDiv );  
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_HeapDouble * Fxu_HeapDoubleStart()
+{
+    Fxu_HeapDouble * p;
+    p = ALLOC( Fxu_HeapDouble, 1 );
+    memset( p, 0, sizeof(Fxu_HeapDouble) );
+    p->nItems      = 0;
+    p->nItemsAlloc = 10000;
+    p->pTree       = ALLOC( Fxu_Double *, p->nItemsAlloc + 1 );
+    p->pTree[0]    = NULL;
+    return p;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleResize( Fxu_HeapDouble * p )
+{
+    p->nItemsAlloc *= 2;
+    p->pTree = REALLOC( Fxu_Double *, p->pTree, p->nItemsAlloc + 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleStop( Fxu_HeapDouble * p )
+{
+    free( p->pTree );
+    free( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoublePrint( FILE * pFile, Fxu_HeapDouble * p )
+{
+    Fxu_Double * pDiv;
+    int Counter = 1;
+    int Degree  = 1;
+
+    Fxu_HeapDoubleCheck( p );
+    fprintf( pFile, "The contents of the heap:\n" );
+    fprintf( pFile, "Level %d:  ", Degree );
+    Fxu_HeapDoubleForEachItem( p, pDiv )
+    {
+        assert( Counter == p->pTree[Counter]->HNum );
+        fprintf( pFile, "%2d=%3d  ", Counter, FXU_HEAP_DOUBLE_WEIGHT(p->pTree[Counter]) );
+        if ( ++Counter == (1 << Degree) )
+        {
+            fprintf( pFile, "\n" );
+            Degree++;
+            fprintf( pFile, "Level %d:  ", Degree );
+        }
+    }
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "End of the heap printout.\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleCheck( Fxu_HeapDouble * p )
+{
+    Fxu_Double * pDiv;
+    Fxu_HeapDoubleForEachItem( p, pDiv )
+    {
+        assert( pDiv->HNum == p->i );
+        Fxu_HeapDoubleCheckOne( p, pDiv );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleCheckOne( Fxu_HeapDouble * p, Fxu_Double * pDiv )
+{
+    int Weight1, Weight2;
+    if ( FXU_HEAP_DOUBLE_CHILD1_EXISTS(p,pDiv) )
+    {
+        Weight1 = FXU_HEAP_DOUBLE_WEIGHT(pDiv);
+        Weight2 = FXU_HEAP_DOUBLE_WEIGHT( FXU_HEAP_DOUBLE_CHILD1(p,pDiv) );
+        assert( Weight1 >= Weight2 );
+    }
+    if ( FXU_HEAP_DOUBLE_CHILD2_EXISTS(p,pDiv) )
+    {
+        Weight1 = FXU_HEAP_DOUBLE_WEIGHT(pDiv);
+        Weight2 = FXU_HEAP_DOUBLE_WEIGHT( FXU_HEAP_DOUBLE_CHILD2(p,pDiv) );
+        assert( Weight1 >= Weight2 );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleInsert( Fxu_HeapDouble * p, Fxu_Double * pDiv )
+{
+    if ( p->nItems == p->nItemsAlloc )
+        Fxu_HeapDoubleResize( p );
+    // put the last entry to the last place and move up
+    p->pTree[++p->nItems] = pDiv;
+    pDiv->HNum = p->nItems;
+    // move the last entry up if necessary
+    Fxu_HeapDoubleMoveUp( p, pDiv );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleUpdate( Fxu_HeapDouble * p, Fxu_Double * pDiv )
+{
+//printf( "Updating divisor %d.\n", pDiv->Num );
+
+    FXU_HEAP_DOUBLE_ASSERT(p,pDiv);
+    if ( FXU_HEAP_DOUBLE_PARENT_EXISTS(p,pDiv) && 
+         FXU_HEAP_DOUBLE_WEIGHT(pDiv) > FXU_HEAP_DOUBLE_WEIGHT( FXU_HEAP_DOUBLE_PARENT(p,pDiv) ) )
+        Fxu_HeapDoubleMoveUp( p, pDiv );
+    else if ( FXU_HEAP_DOUBLE_CHILD1_EXISTS(p,pDiv) && 
+        FXU_HEAP_DOUBLE_WEIGHT(pDiv) < FXU_HEAP_DOUBLE_WEIGHT( FXU_HEAP_DOUBLE_CHILD1(p,pDiv) ) )
+        Fxu_HeapDoubleMoveDn( p, pDiv );
+    else if ( FXU_HEAP_DOUBLE_CHILD2_EXISTS(p,pDiv) && 
+        FXU_HEAP_DOUBLE_WEIGHT(pDiv) < FXU_HEAP_DOUBLE_WEIGHT( FXU_HEAP_DOUBLE_CHILD2(p,pDiv) ) )
+        Fxu_HeapDoubleMoveDn( p, pDiv );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleDelete( Fxu_HeapDouble * p, Fxu_Double * pDiv )
+{
+    FXU_HEAP_DOUBLE_ASSERT(p,pDiv);
+    // put the last entry to the deleted place
+    // decrement the number of entries
+    p->pTree[pDiv->HNum] = p->pTree[p->nItems--];
+    p->pTree[pDiv->HNum]->HNum = pDiv->HNum;
+    // move the top entry down if necessary
+    Fxu_HeapDoubleUpdate( p, p->pTree[pDiv->HNum] );
+    pDiv->HNum = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Double * Fxu_HeapDoubleReadMax( Fxu_HeapDouble * p )
+{
+    if ( p->nItems == 0 )
+        return NULL;
+    return p->pTree[1];     
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Double * Fxu_HeapDoubleGetMax( Fxu_HeapDouble * p )
+{
+    Fxu_Double * pDiv;
+    if ( p->nItems == 0 )
+        return NULL;
+    // prepare the return value
+    pDiv = p->pTree[1];
+    pDiv->HNum = 0;
+    // put the last entry on top
+    // decrement the number of entries
+    p->pTree[1] = p->pTree[p->nItems--];
+    p->pTree[1]->HNum = 1;
+    // move the top entry down if necessary
+    Fxu_HeapDoubleMoveDn( p, p->pTree[1] );
+    return pDiv;     
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int  Fxu_HeapDoubleReadMaxWeight( Fxu_HeapDouble * p )
+{
+    if ( p->nItems == 0 )
+        return -1;
+    else
+        return FXU_HEAP_DOUBLE_WEIGHT(p->pTree[1]);
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleSwap( Fxu_Double ** pDiv1, Fxu_Double ** pDiv2 )
+{
+    Fxu_Double * pDiv;
+    int Temp;
+    pDiv   = *pDiv1;
+    *pDiv1 = *pDiv2;
+    *pDiv2 = pDiv;
+    Temp          = (*pDiv1)->HNum;
+    (*pDiv1)->HNum = (*pDiv2)->HNum;
+    (*pDiv2)->HNum = Temp;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleMoveUp( Fxu_HeapDouble * p, Fxu_Double * pDiv )
+{
+    Fxu_Double ** ppDiv, ** ppPar;
+    ppDiv = &FXU_HEAP_DOUBLE_CURRENT(p, pDiv);
+    while ( FXU_HEAP_DOUBLE_PARENT_EXISTS(p,*ppDiv) )
+    {
+        ppPar = &FXU_HEAP_DOUBLE_PARENT(p,*ppDiv);
+        if ( FXU_HEAP_DOUBLE_WEIGHT(*ppDiv) > FXU_HEAP_DOUBLE_WEIGHT(*ppPar) )
+        {
+            Fxu_HeapDoubleSwap( ppDiv, ppPar );
+            ppDiv = ppPar;
+        }
+        else
+            break;
+    }
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapDoubleMoveDn( Fxu_HeapDouble * p, Fxu_Double * pDiv )
+{
+    Fxu_Double ** ppChild1, ** ppChild2, ** ppDiv;
+    ppDiv = &FXU_HEAP_DOUBLE_CURRENT(p, pDiv);
+    while ( FXU_HEAP_DOUBLE_CHILD1_EXISTS(p,*ppDiv) )
+    { // if Child1 does not exist, Child2 also does not exists
+
+        // get the children
+        ppChild1 = &FXU_HEAP_DOUBLE_CHILD1(p,*ppDiv);
+        if ( FXU_HEAP_DOUBLE_CHILD2_EXISTS(p,*ppDiv) )
+        {
+            ppChild2 = &FXU_HEAP_DOUBLE_CHILD2(p,*ppDiv);
+
+            // consider two cases
+            if ( FXU_HEAP_DOUBLE_WEIGHT(*ppDiv) >= FXU_HEAP_DOUBLE_WEIGHT(*ppChild1) &&
+                 FXU_HEAP_DOUBLE_WEIGHT(*ppDiv) >= FXU_HEAP_DOUBLE_WEIGHT(*ppChild2) )
+            { // Div is larger than both, skip
+                break;
+            }
+            else
+            { // Div is smaller than one of them, then swap it with larger 
+                if ( FXU_HEAP_DOUBLE_WEIGHT(*ppChild1) >= FXU_HEAP_DOUBLE_WEIGHT(*ppChild2) )
+                {
+                    Fxu_HeapDoubleSwap( ppDiv, ppChild1 );
+                    // update the pointer
+                    ppDiv = ppChild1;
+                }
+                else
+                {
+                    Fxu_HeapDoubleSwap( ppDiv, ppChild2 );
+                    // update the pointer
+                    ppDiv = ppChild2;
+                }
+            }
+        }
+        else // Child2 does not exist
+        {
+            // consider two cases
+            if ( FXU_HEAP_DOUBLE_WEIGHT(*ppDiv) >= FXU_HEAP_DOUBLE_WEIGHT(*ppChild1) )
+            { // Div is larger than Child1, skip
+                break;
+            }
+            else
+            { // Div is smaller than Child1, then swap them
+                Fxu_HeapDoubleSwap( ppDiv, ppChild1 );
+                // update the pointer
+                ppDiv = ppChild1;
+            }
+        }
+    }
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuHeapS.c b/src/opt/fxu/fxuHeapS.c
new file mode 100644
index 00000000..eaca8363
--- /dev/null
+++ b/src/opt/fxu/fxuHeapS.c
@@ -0,0 +1,444 @@
+/**CFile****************************************************************
+
+  FileName    [fxuHeapS.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [The priority queue for variables.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuHeapS.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define FXU_HEAP_SINGLE_WEIGHT(pSingle)           ((pSingle)->Weight)
+#define FXU_HEAP_SINGLE_CURRENT(p, pSingle)       ((p)->pTree[(pSingle)->HNum])
+#define FXU_HEAP_SINGLE_PARENT_EXISTS(p, pSingle) ((pSingle)->HNum > 1)
+#define FXU_HEAP_SINGLE_CHILD1_EXISTS(p, pSingle) (((pSingle)->HNum << 1) <= p->nItems)
+#define FXU_HEAP_SINGLE_CHILD2_EXISTS(p, pSingle) ((((pSingle)->HNum << 1)+1) <= p->nItems)
+#define FXU_HEAP_SINGLE_PARENT(p, pSingle)        ((p)->pTree[(pSingle)->HNum >> 1])
+#define FXU_HEAP_SINGLE_CHILD1(p, pSingle)        ((p)->pTree[(pSingle)->HNum << 1])
+#define FXU_HEAP_SINGLE_CHILD2(p, pSingle)        ((p)->pTree[((pSingle)->HNum << 1)+1])
+#define FXU_HEAP_SINGLE_ASSERT(p, pSingle)        assert( (pSingle)->HNum >= 1 && (pSingle)->HNum <= p->nItemsAlloc )
+
+static void Fxu_HeapSingleResize( Fxu_HeapSingle * p );                  
+static void Fxu_HeapSingleSwap( Fxu_Single ** pSingle1, Fxu_Single ** pSingle2 );  
+static void Fxu_HeapSingleMoveUp( Fxu_HeapSingle * p, Fxu_Single * pSingle );  
+static void Fxu_HeapSingleMoveDn( Fxu_HeapSingle * p, Fxu_Single * pSingle );  
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_HeapSingle * Fxu_HeapSingleStart()
+{
+    Fxu_HeapSingle * p;
+    p = ALLOC( Fxu_HeapSingle, 1 );
+    memset( p, 0, sizeof(Fxu_HeapSingle) );
+    p->nItems      = 0;
+    p->nItemsAlloc = 2000;
+    p->pTree       = ALLOC( Fxu_Single *, p->nItemsAlloc + 10 );
+    p->pTree[0]    = NULL;
+    return p;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleResize( Fxu_HeapSingle * p )
+{
+    p->nItemsAlloc *= 2;
+    p->pTree = REALLOC( Fxu_Single *, p->pTree, p->nItemsAlloc + 10 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleStop( Fxu_HeapSingle * p )
+{
+    int i;
+    i = 0;
+    free( p->pTree );
+    i = 1;
+    free( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSinglePrint( FILE * pFile, Fxu_HeapSingle * p )
+{
+    Fxu_Single * pSingle;
+    int Counter = 1;
+    int Degree  = 1;
+
+    Fxu_HeapSingleCheck( p );
+    fprintf( pFile, "The contents of the heap:\n" );
+    fprintf( pFile, "Level %d:  ", Degree );
+    Fxu_HeapSingleForEachItem( p, pSingle )
+    {
+        assert( Counter == p->pTree[Counter]->HNum );
+        fprintf( pFile, "%2d=%3d  ", Counter, FXU_HEAP_SINGLE_WEIGHT(p->pTree[Counter]) );
+        if ( ++Counter == (1 << Degree) )
+        {
+            fprintf( pFile, "\n" );
+            Degree++;
+            fprintf( pFile, "Level %d:  ", Degree );
+        }
+    }
+    fprintf( pFile, "\n" );
+    fprintf( pFile, "End of the heap printout.\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleCheck( Fxu_HeapSingle * p )
+{
+    Fxu_Single * pSingle;
+    Fxu_HeapSingleForEachItem( p, pSingle )
+    {
+        assert( pSingle->HNum == p->i );
+        Fxu_HeapSingleCheckOne( p, pSingle );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleCheckOne( Fxu_HeapSingle * p, Fxu_Single * pSingle )
+{
+    int Weight1, Weight2;
+    if ( FXU_HEAP_SINGLE_CHILD1_EXISTS(p,pSingle) )
+    {
+        Weight1 = FXU_HEAP_SINGLE_WEIGHT(pSingle);
+        Weight2 = FXU_HEAP_SINGLE_WEIGHT( FXU_HEAP_SINGLE_CHILD1(p,pSingle) );
+        assert( Weight1 >= Weight2 );
+    }
+    if ( FXU_HEAP_SINGLE_CHILD2_EXISTS(p,pSingle) )
+    {
+        Weight1 = FXU_HEAP_SINGLE_WEIGHT(pSingle);
+        Weight2 = FXU_HEAP_SINGLE_WEIGHT( FXU_HEAP_SINGLE_CHILD2(p,pSingle) );
+        assert( Weight1 >= Weight2 );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleInsert( Fxu_HeapSingle * p, Fxu_Single * pSingle )
+{
+    if ( p->nItems == p->nItemsAlloc )
+        Fxu_HeapSingleResize( p );
+    // put the last entry to the last place and move up
+    p->pTree[++p->nItems] = pSingle;
+    pSingle->HNum = p->nItems;
+    // move the last entry up if necessary
+    Fxu_HeapSingleMoveUp( p, pSingle );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleUpdate( Fxu_HeapSingle * p, Fxu_Single * pSingle )
+{
+    FXU_HEAP_SINGLE_ASSERT(p,pSingle);
+    if ( FXU_HEAP_SINGLE_PARENT_EXISTS(p,pSingle) && 
+         FXU_HEAP_SINGLE_WEIGHT(pSingle) > FXU_HEAP_SINGLE_WEIGHT( FXU_HEAP_SINGLE_PARENT(p,pSingle) ) )
+        Fxu_HeapSingleMoveUp( p, pSingle );
+    else if ( FXU_HEAP_SINGLE_CHILD1_EXISTS(p,pSingle) && 
+        FXU_HEAP_SINGLE_WEIGHT(pSingle) < FXU_HEAP_SINGLE_WEIGHT( FXU_HEAP_SINGLE_CHILD1(p,pSingle) ) )
+        Fxu_HeapSingleMoveDn( p, pSingle );
+    else if ( FXU_HEAP_SINGLE_CHILD2_EXISTS(p,pSingle) && 
+        FXU_HEAP_SINGLE_WEIGHT(pSingle) < FXU_HEAP_SINGLE_WEIGHT( FXU_HEAP_SINGLE_CHILD2(p,pSingle) ) )
+        Fxu_HeapSingleMoveDn( p, pSingle );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleDelete( Fxu_HeapSingle * p, Fxu_Single * pSingle )
+{
+    int Place = pSingle->HNum;
+    FXU_HEAP_SINGLE_ASSERT(p,pSingle);
+    // put the last entry to the deleted place
+    // decrement the number of entries
+    p->pTree[Place] = p->pTree[p->nItems--];
+    p->pTree[Place]->HNum = Place;
+    // move the top entry down if necessary
+    Fxu_HeapSingleUpdate( p, p->pTree[Place] );
+    pSingle->HNum = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Single * Fxu_HeapSingleReadMax( Fxu_HeapSingle * p )
+{
+    if ( p->nItems == 0 )
+        return NULL;
+    return p->pTree[1];
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Single * Fxu_HeapSingleGetMax( Fxu_HeapSingle * p )
+{
+    Fxu_Single * pSingle;
+    if ( p->nItems == 0 )
+        return NULL;
+    // prepare the return value
+    pSingle = p->pTree[1];
+    pSingle->HNum = 0;
+    // put the last entry on top
+    // decrement the number of entries
+    p->pTree[1] = p->pTree[p->nItems--];
+    p->pTree[1]->HNum = 1;
+    // move the top entry down if necessary
+    Fxu_HeapSingleMoveDn( p, p->pTree[1] );
+    return pSingle;     
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int  Fxu_HeapSingleReadMaxWeight( Fxu_HeapSingle * p )
+{
+    if ( p->nItems == 0 )
+        return -1;
+    return FXU_HEAP_SINGLE_WEIGHT(p->pTree[1]);
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleSwap( Fxu_Single ** pSingle1, Fxu_Single ** pSingle2 )
+{
+    Fxu_Single * pSingle;
+    int Temp;
+    pSingle   = *pSingle1;
+    *pSingle1 = *pSingle2;
+    *pSingle2 = pSingle;
+    Temp          = (*pSingle1)->HNum;
+    (*pSingle1)->HNum = (*pSingle2)->HNum;
+    (*pSingle2)->HNum = Temp;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleMoveUp( Fxu_HeapSingle * p, Fxu_Single * pSingle )
+{
+    Fxu_Single ** ppSingle, ** ppPar;
+    ppSingle = &FXU_HEAP_SINGLE_CURRENT(p, pSingle);
+    while ( FXU_HEAP_SINGLE_PARENT_EXISTS(p,*ppSingle) )
+    {
+        ppPar = &FXU_HEAP_SINGLE_PARENT(p,*ppSingle);
+        if ( FXU_HEAP_SINGLE_WEIGHT(*ppSingle) > FXU_HEAP_SINGLE_WEIGHT(*ppPar) )
+        {
+            Fxu_HeapSingleSwap( ppSingle, ppPar );
+            ppSingle = ppPar;
+        }
+        else
+            break;
+    }
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_HeapSingleMoveDn( Fxu_HeapSingle * p, Fxu_Single * pSingle )
+{
+    Fxu_Single ** ppChild1, ** ppChild2, ** ppSingle;
+    ppSingle = &FXU_HEAP_SINGLE_CURRENT(p, pSingle);
+    while ( FXU_HEAP_SINGLE_CHILD1_EXISTS(p,*ppSingle) )
+    { // if Child1 does not exist, Child2 also does not exists
+
+        // get the children
+        ppChild1 = &FXU_HEAP_SINGLE_CHILD1(p,*ppSingle);
+        if ( FXU_HEAP_SINGLE_CHILD2_EXISTS(p,*ppSingle) )
+        {
+            ppChild2 = &FXU_HEAP_SINGLE_CHILD2(p,*ppSingle);
+
+            // consider two cases
+            if ( FXU_HEAP_SINGLE_WEIGHT(*ppSingle) >= FXU_HEAP_SINGLE_WEIGHT(*ppChild1) &&
+                 FXU_HEAP_SINGLE_WEIGHT(*ppSingle) >= FXU_HEAP_SINGLE_WEIGHT(*ppChild2) )
+            { // Var is larger than both, skip
+                break;
+            }
+            else
+            { // Var is smaller than one of them, then swap it with larger 
+                if ( FXU_HEAP_SINGLE_WEIGHT(*ppChild1) >= FXU_HEAP_SINGLE_WEIGHT(*ppChild2) )
+                {
+                    Fxu_HeapSingleSwap( ppSingle, ppChild1 );
+                    // update the pointer
+                    ppSingle = ppChild1;
+                }
+                else
+                {
+                    Fxu_HeapSingleSwap( ppSingle, ppChild2 );
+                    // update the pointer
+                    ppSingle = ppChild2;
+                }
+            }
+        }
+        else // Child2 does not exist
+        {
+            // consider two cases
+            if ( FXU_HEAP_SINGLE_WEIGHT(*ppSingle) >= FXU_HEAP_SINGLE_WEIGHT(*ppChild1) )
+            { // Var is larger than Child1, skip
+                break;
+            }
+            else
+            { // Var is smaller than Child1, then swap them
+                Fxu_HeapSingleSwap( ppSingle, ppChild1 );
+                // update the pointer
+                ppSingle = ppChild1;
+            }
+        }
+    }
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
diff --git a/src/opt/fxu/fxuInt.h b/src/opt/fxu/fxuInt.h
new file mode 100644
index 00000000..ea85cb79
--- /dev/null
+++ b/src/opt/fxu/fxuInt.h
@@ -0,0 +1,539 @@
+/**CFile****************************************************************
+
+  FileName    [fxuInt.h]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Internal declarations of fast extract for unate covers.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuInt.h,v 1.3 2003/04/10 05:42:44 donald Exp $]
+
+***********************************************************************/
+ 
+#ifndef __FXU_INT_H__
+#define __FXU_INT_H__
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "extra.h"
+#include "vec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+// uncomment this macro to switch to standard memory management
+//#define USE_SYSTEM_MEMORY_MANAGEMENT 
+
+////////////////////////////////////////////////////////////////////////
+///                    STRUCTURE DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*  
+    Here is an informal description of the FX data structure.
+    (1) The sparse matrix is filled with literals, associated with 
+        cubes (row) and variables (columns). The matrix contains 
+        all the cubes of all the nodes in the network.
+    (2) A cube is associated with 
+        (a) its literals in the matrix,
+        (b) the output variable of the node, to which this cube belongs,
+    (3) A variable is associated with 
+        (a) its literals in the matrix and
+        (b) the list of cube pairs in the cover, for which it is the output
+    (4) A cube pair is associated with two cubes and contains the counters
+        of literals in the base and in the cubes without the base
+    (5) A double-cube divisor is associated with list of all cube pairs 
+        that produce it and its current weight (which is updated automatically 
+        each time a new pair is added or an old pair is removed). 
+    (6) A single-cube divisor is associated the pair of variables. 
+*/
+
+// sparse matrix
+typedef struct FxuMatrix        Fxu_Matrix;     // the sparse matrix
+
+// sparse matrix contents: cubes (rows), vars (columns), literals (entries)
+typedef struct FxuCube          Fxu_Cube;       // one cube in the sparse matrix
+typedef struct FxuVar           Fxu_Var;        // one literal in the sparse matrix
+typedef struct FxuLit           Fxu_Lit;        // one entry in the sparse matrix
+
+// double cube divisors
+typedef struct FxuPair          Fxu_Pair;       // the pair of cubes
+typedef struct FxuDouble        Fxu_Double;     // the double-cube divisor
+typedef struct FxuSingle        Fxu_Single;     // the two-literal single-cube divisor
+
+// various lists
+typedef struct FxuListCube      Fxu_ListCube;   // the list of cubes
+typedef struct FxuListVar       Fxu_ListVar;    // the list of literals
+typedef struct FxuListLit       Fxu_ListLit;    // the list of entries
+typedef struct FxuListPair      Fxu_ListPair;   // the list of pairs
+typedef struct FxuListDouble    Fxu_ListDouble; // the list of divisors
+typedef struct FxuListSingle    Fxu_ListSingle; // the list of single-cube divisors
+
+// various heaps
+typedef struct FxuHeapDouble    Fxu_HeapDouble; // the heap of divisors
+typedef struct FxuHeapSingle    Fxu_HeapSingle; // the heap of variables
+
+
+// various lists
+
+// the list of cubes in the sparse matrix 
+struct FxuListCube
+{
+    Fxu_Cube *       pHead;
+    Fxu_Cube *       pTail;
+    int              nItems;
+};
+
+// the list of literals in the sparse matrix 
+struct FxuListVar
+{
+    Fxu_Var *        pHead;
+    Fxu_Var *        pTail;
+    int              nItems;
+};
+
+// the list of entries in the sparse matrix 
+struct FxuListLit
+{
+    Fxu_Lit *        pHead;
+    Fxu_Lit *        pTail;
+    int              nItems;
+};
+
+// the list of cube pair in the sparse matrix 
+struct FxuListPair
+{
+    Fxu_Pair *       pHead;
+    Fxu_Pair *       pTail;
+    int              nItems;
+};
+
+// the list of divisors in the sparse matrix 
+struct FxuListDouble
+{
+    Fxu_Double *     pHead;
+    Fxu_Double *     pTail;
+    int              nItems;
+};
+
+// the list of divisors in the sparse matrix 
+struct FxuListSingle
+{
+    Fxu_Single *     pHead;
+    Fxu_Single *     pTail;
+    int              nItems;
+};
+
+
+// various heaps
+
+// the heap of double cube divisors by weight
+struct FxuHeapDouble
+{
+    Fxu_Double **    pTree;
+    int              nItems;
+    int              nItemsAlloc;
+    int              i;
+};
+
+// the heap of variable by their occurrence in the cubes
+struct FxuHeapSingle
+{
+    Fxu_Single **    pTree;
+    int              nItems;
+    int              nItemsAlloc;
+    int              i;
+};
+
+
+
+// sparse matrix
+struct FxuMatrix // ~ 30 words
+{
+    // the cubes
+    Fxu_ListCube     lCubes;      // the double linked list of cubes
+    // the values (binary literals)
+    Fxu_ListVar      lVars;       // the double linked list of variables
+      Fxu_Var **       ppVars;      // the array of variables
+    // the double cube divisors
+    Fxu_ListDouble * pTable;      // the hash table of divisors
+    int              nTableSize;  // the hash table size
+    int              nDivs;       // the number of divisors in the table
+    int              nDivsTotal;  // the number of divisors in the table
+    Fxu_HeapDouble * pHeapDouble;    // the heap of divisors by weight
+    // the single cube divisors
+    Fxu_ListSingle   lSingles;    // the linked list of single cube divisors  
+    Fxu_HeapSingle * pHeapSingle; // the heap of variables by the number of literals in the matrix
+    int              nWeightLimit;// the limit on weight of single cube divisors collected
+    int              nSingleTotal;// the total number of single cube divisors
+    // storage for cube pairs
+    Fxu_Pair ***     pppPairs;
+    Fxu_Pair **      ppPairs;
+    // temporary storage for cubes 
+    Fxu_Cube *       pOrderCubes;
+    Fxu_Cube **      ppTailCubes;
+    // temporary storage for variables 
+    Fxu_Var *        pOrderVars;
+    Fxu_Var **       ppTailVars;
+    // temporary storage for pairs
+    Vec_Ptr_t *      vPairs;
+    // statistics
+    int              nEntries;    // the total number of entries in the sparse matrix
+    int              nDivs1;      // the single cube divisors taken
+    int              nDivs2;      // the double cube divisors taken
+    int              nDivs3;      // the double cube divisors with complement
+    // memory manager
+    Extra_MmFixed_t * pMemMan;     // the memory manager for all small sized entries
+};
+
+// the cube in the sparse matrix
+struct FxuCube // 9 words
+{
+    int              iCube;       // the number of this cube in the cover
+    Fxu_Cube *       pFirst;      // the pointer to the first cube of this cover
+    Fxu_Var *        pVar;        // the variable representing the output of the cover
+    Fxu_ListLit      lLits;       // the row in the table 
+    Fxu_Cube *       pPrev;       // the previous cube
+    Fxu_Cube *       pNext;       // the next cube
+    Fxu_Cube *       pOrder;      // the specialized linked list of cubes
+};
+
+// the variable in the sparse matrix
+struct FxuVar // 10 words
+{
+    int              iVar;        // the number of this variable
+    int              nCubes;      // the number of cubes assoc with this var
+    Fxu_Cube *       pFirst;      // the first cube assoc with this var
+    Fxu_Pair ***     ppPairs;     // the pairs of cubes assoc with this var
+    Fxu_ListLit      lLits;       // the column in the table 
+    Fxu_Var *        pPrev;       // the previous variable
+    Fxu_Var *        pNext;       // the next variable
+    Fxu_Var *        pOrder;      // the specialized linked list of variables
+};
+
+// the literal entry in the sparse matrix 
+struct FxuLit // 8 words
+{
+    int              iVar;        // the number of this variable
+    int              iCube;       // the number of this cube
+    Fxu_Cube *       pCube;       // the cube of this literal
+    Fxu_Var *        pVar;        // the variable of this literal
+    Fxu_Lit *        pHPrev;      // prev lit in the cube
+    Fxu_Lit *        pHNext;      // next lit in the cube
+    Fxu_Lit *        pVPrev;      // prev lit of the var     
+    Fxu_Lit *        pVNext;      // next lit of the var   
+};
+
+// the cube pair
+struct FxuPair // 10 words
+{
+    int              nLits1;      // the number of literals in the two cubes
+    int              nLits2;      // the number of literals in the two cubes
+    int              nBase;       // the number of literals in the base
+    Fxu_Double *     pDiv;        // the divisor of this pair
+    Fxu_Cube *       pCube1;      // the first cube of the pair
+    Fxu_Cube *       pCube2;      // the second cube of the pair
+    int              iCube1;      // the first cube of the pair
+    int              iCube2;      // the second cube of the pair
+    Fxu_Pair *       pDPrev;      // the previous pair in the divisor
+    Fxu_Pair *       pDNext;      // the next pair in the divisor
+};
+
+// the double cube divisor
+struct FxuDouble // 10 words
+{
+    int              Num;         // the unique number of this divisor
+    int              HNum;        // the heap number of this divisor
+    int              Weight;      // the weight of this divisor
+    unsigned         Key;         // the hash key of this divisor
+    Fxu_ListPair     lPairs;      // the pairs of cubes, which produce this divisor
+    Fxu_Double *     pPrev;       // the previous divisor in the table
+    Fxu_Double *     pNext;       // the next divisor in the table
+    Fxu_Double *     pOrder;      // the specialized linked list of divisors
+};
+
+// the single cube divisor
+struct FxuSingle // 7 words
+{
+    int              Num;         // the unique number of this divisor
+    int              HNum;        // the heap number of this divisor
+    int              Weight;      // the weight of this divisor
+    Fxu_Var *        pVar1;       // the first variable of the single-cube divisor
+    Fxu_Var *        pVar2;       // the second variable of the single-cube divisor
+    Fxu_Single *     pPrev;       // the previous divisor in the list
+    Fxu_Single *     pNext;       // the next divisor in the list
+};
+
+////////////////////////////////////////////////////////////////////////
+///                       MACRO DEFINITIONS                          ///
+////////////////////////////////////////////////////////////////////////
+
+// minimum/maximum
+#define Fxu_Min( a, b ) ( ((a)<(b))? (a):(b) )
+#define Fxu_Max( a, b ) ( ((a)>(b))? (a):(b) )
+
+// selection of the minimum/maximum cube in the pair
+#define Fxu_PairMinCube( pPair )    (((pPair)->iCube1 < (pPair)->iCube2)? (pPair)->pCube1: (pPair)->pCube2)
+#define Fxu_PairMaxCube( pPair )    (((pPair)->iCube1 > (pPair)->iCube2)? (pPair)->pCube1: (pPair)->pCube2)
+#define Fxu_PairMinCubeInt( pPair ) (((pPair)->iCube1 < (pPair)->iCube2)? (pPair)->iCube1: (pPair)->iCube2)
+#define Fxu_PairMaxCubeInt( pPair ) (((pPair)->iCube1 > (pPair)->iCube2)? (pPair)->iCube1: (pPair)->iCube2)
+
+// iterators
+
+#define Fxu_MatrixForEachCube( Matrix, Cube )\
+    for ( Cube = (Matrix)->lCubes.pHead;\
+          Cube;\
+          Cube = Cube->pNext )
+#define Fxu_MatrixForEachCubeSafe( Matrix, Cube, Cube2 )\
+    for ( Cube = (Matrix)->lCubes.pHead, Cube2 = (Cube? Cube->pNext: NULL);\
+          Cube;\
+          Cube = Cube2, Cube2 = (Cube? Cube->pNext: NULL) )
+
+#define Fxu_MatrixForEachVariable( Matrix, Var )\
+    for ( Var = (Matrix)->lVars.pHead;\
+          Var;\
+          Var = Var->pNext )
+#define Fxu_MatrixForEachVariableSafe( Matrix, Var, Var2 )\
+    for ( Var = (Matrix)->lVars.pHead, Var2 = (Var? Var->pNext: NULL);\
+          Var;\
+          Var = Var2, Var2 = (Var? Var->pNext: NULL) )
+
+#define Fxu_MatrixForEachSingle( Matrix, Single )\
+    for ( Single = (Matrix)->lSingles.pHead;\
+          Single;\
+          Single = Single->pNext )
+#define Fxu_MatrixForEachSingleSafe( Matrix, Single, Single2 )\
+    for ( Single = (Matrix)->lSingles.pHead, Single2 = (Single? Single->pNext: NULL);\
+          Single;\
+          Single = Single2, Single2 = (Single? Single->pNext: NULL) )
+
+#define Fxu_TableForEachDouble( Matrix, Key, Div )\
+    for ( Div = (Matrix)->pTable[Key].pHead;\
+          Div;\
+          Div = Div->pNext )
+#define Fxu_TableForEachDoubleSafe( Matrix, Key, Div, Div2 )\
+    for ( Div = (Matrix)->pTable[Key].pHead, Div2 = (Div? Div->pNext: NULL);\
+          Div;\
+          Div = Div2, Div2 = (Div? Div->pNext: NULL) )
+
+#define Fxu_MatrixForEachDouble( Matrix, Div, Index )\
+    for ( Index = 0; Index < (Matrix)->nTableSize; Index++ )\
+        Fxu_TableForEachDouble( Matrix, Index, Div )
+#define Fxu_MatrixForEachDoubleSafe( Matrix, Div, Div2, Index )\
+    for ( Index = 0; Index < (Matrix)->nTableSize; Index++ )\
+        Fxu_TableForEachDoubleSafe( Matrix, Index, Div, Div2 )
+
+
+#define Fxu_CubeForEachLiteral( Cube, Lit )\
+    for ( Lit = (Cube)->lLits.pHead;\
+          Lit;\
+          Lit = Lit->pHNext )
+#define Fxu_CubeForEachLiteralSafe( Cube, Lit, Lit2 )\
+    for ( Lit = (Cube)->lLits.pHead, Lit2 = (Lit? Lit->pHNext: NULL);\
+          Lit;\
+          Lit = Lit2, Lit2 = (Lit? Lit->pHNext: NULL) )
+
+#define Fxu_VarForEachLiteral( Var, Lit )\
+    for ( Lit = (Var)->lLits.pHead;\
+          Lit;\
+          Lit = Lit->pVNext )
+
+#define Fxu_CubeForEachDivisor( Cube, Div )\
+    for ( Div = (Cube)->lDivs.pHead;\
+          Div;\
+          Div = Div->pCNext )
+
+#define Fxu_DoubleForEachPair( Div, Pair )\
+    for ( Pair = (Div)->lPairs.pHead;\
+          Pair;\
+          Pair = Pair->pDNext )
+#define Fxu_DoubleForEachPairSafe( Div, Pair, Pair2 )\
+    for ( Pair = (Div)->lPairs.pHead, Pair2 = (Pair? Pair->pDNext: NULL);\
+          Pair;\
+          Pair = Pair2, Pair2 = (Pair? Pair->pDNext: NULL) )
+
+
+// iterator through the cube pairs belonging to the given cube 
+#define Fxu_CubeForEachPair( pCube, pPair, i )\
+  for ( i = 0;\
+        i < pCube->pVar->nCubes &&\
+        (((unsigned)(pPair = pCube->pVar->ppPairs[pCube->iCube][i])) >= 0);\
+        i++ )\
+        if ( pPair )
+
+// iterator through all the items in the heap
+#define Fxu_HeapDoubleForEachItem( Heap, Div )\
+    for ( Heap->i = 1;\
+          Heap->i <= Heap->nItems && (Div = Heap->pTree[Heap->i]);\
+          Heap->i++ )
+#define Fxu_HeapSingleForEachItem( Heap, Single )\
+    for ( Heap->i = 1;\
+          Heap->i <= Heap->nItems && (Single = Heap->pTree[Heap->i]);\
+          Heap->i++ )
+
+// starting the rings
+#define Fxu_MatrixRingCubesStart( Matrix )    (((Matrix)->ppTailCubes = &((Matrix)->pOrderCubes)), ((Matrix)->pOrderCubes = NULL))
+#define Fxu_MatrixRingVarsStart(  Matrix )    (((Matrix)->ppTailVars  = &((Matrix)->pOrderVars)),  ((Matrix)->pOrderVars  = NULL))
+// stopping the rings
+#define Fxu_MatrixRingCubesStop(  Matrix )
+#define Fxu_MatrixRingVarsStop(   Matrix )
+// resetting the rings
+#define Fxu_MatrixRingCubesReset( Matrix )    (((Matrix)->pOrderCubes = NULL), ((Matrix)->ppTailCubes = NULL))
+#define Fxu_MatrixRingVarsReset(  Matrix )    (((Matrix)->pOrderVars  = NULL), ((Matrix)->ppTailVars  = NULL))
+// adding to the rings
+#define Fxu_MatrixRingCubesAdd( Matrix, Cube) ((*((Matrix)->ppTailCubes) = Cube), ((Matrix)->ppTailCubes = &(Cube)->pOrder), ((Cube)->pOrder = (Fxu_Cube *)1))
+#define Fxu_MatrixRingVarsAdd(  Matrix, Var ) ((*((Matrix)->ppTailVars ) = Var ), ((Matrix)->ppTailVars  = &(Var)->pOrder ), ((Var)->pOrder  = (Fxu_Var *)1))
+// iterating through the rings
+#define Fxu_MatrixForEachCubeInRing( Matrix, Cube )\
+    if ( (Matrix)->pOrderCubes )\
+    for ( Cube = (Matrix)->pOrderCubes;\
+          Cube != (Fxu_Cube *)1;\
+          Cube = Cube->pOrder )
+#define Fxu_MatrixForEachCubeInRingSafe( Matrix, Cube, Cube2 )\
+    if ( (Matrix)->pOrderCubes )\
+    for ( Cube = (Matrix)->pOrderCubes, Cube2 = ((Cube != (Fxu_Cube *)1)? Cube->pOrder: (Fxu_Cube *)1);\
+          Cube != (Fxu_Cube *)1;\
+          Cube = Cube2, Cube2 = ((Cube != (Fxu_Cube *)1)? Cube->pOrder: (Fxu_Cube *)1) )
+#define Fxu_MatrixForEachVarInRing( Matrix, Var )\
+    if ( (Matrix)->pOrderVars )\
+    for ( Var = (Matrix)->pOrderVars;\
+          Var != (Fxu_Var *)1;\
+          Var = Var->pOrder )
+#define Fxu_MatrixForEachVarInRingSafe( Matrix, Var, Var2 )\
+    if ( (Matrix)->pOrderVars )\
+    for ( Var = (Matrix)->pOrderVars, Var2 = ((Var != (Fxu_Var *)1)? Var->pOrder: (Fxu_Var *)1);\
+          Var != (Fxu_Var *)1;\
+          Var = Var2, Var2 = ((Var != (Fxu_Var *)1)? Var->pOrder: (Fxu_Var *)1) )
+// the procedures are related to the above macros
+extern void Fxu_MatrixRingCubesUnmark( Fxu_Matrix * p );
+extern void Fxu_MatrixRingVarsUnmark( Fxu_Matrix * p );
+
+
+// macros working with memory
+// MEM_ALLOC: allocate the given number (Size) of items of type (Type)
+// MEM_FREE:  deallocate the pointer (Pointer) to the given number (Size) of items of type (Type)
+#ifdef USE_SYSTEM_MEMORY_MANAGEMENT
+#define MEM_ALLOC_FXU( Manager, Type, Size )          ((Type *)malloc( (Size) * sizeof(Type) ))
+#define MEM_FREE_FXU( Manager, Type, Size, Pointer )  if ( Pointer ) { free(Pointer); Pointer = NULL; }
+#else
+#define MEM_ALLOC_FXU( Manager, Type, Size )\
+        ((Type *)Fxu_MemFetch( Manager, (Size) * sizeof(Type) ))
+#define MEM_FREE_FXU( Manager, Type, Size, Pointer )\
+         if ( Pointer ) { Fxu_MemRecycle( Manager, (char *)(Pointer), (Size) * sizeof(Type) ); Pointer = NULL; }
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*===== fxu.c ====================================================*/
+extern char *       Fxu_MemFetch( Fxu_Matrix * p, int nBytes );
+extern void         Fxu_MemRecycle( Fxu_Matrix * p, char * pItem, int nBytes );
+/*===== fxuCreate.c ====================================================*/
+/*===== fxuReduce.c ====================================================*/
+/*===== fxuPrint.c ====================================================*/
+extern void         Fxu_MatrixPrint( FILE * pFile, Fxu_Matrix * p );
+extern void         Fxu_MatrixPrintDivisorProfile( FILE * pFile, Fxu_Matrix * p );
+/*===== fxuSelect.c ====================================================*/
+extern int          Fxu_Select( Fxu_Matrix * p, Fxu_Single ** ppSingle, Fxu_Double ** ppDouble );
+extern int          Fxu_SelectSCD( Fxu_Matrix * p, int Weight, Fxu_Var ** ppVar1, Fxu_Var ** ppVar2 );
+/*===== fxuUpdate.c ====================================================*/
+extern void         Fxu_Update( Fxu_Matrix * p, Fxu_Single * pSingle, Fxu_Double * pDouble );
+extern void         Fxu_UpdateDouble( Fxu_Matrix * p );
+extern void         Fxu_UpdateSingle( Fxu_Matrix * p );
+/*===== fxuPair.c ====================================================*/
+extern void         Fxu_PairCanonicize( Fxu_Cube ** ppCube1, Fxu_Cube ** ppCube2 );
+extern unsigned     Fxu_PairHashKeyArray( Fxu_Matrix * p, int piVarsC1[], int piVarsC2[], int nVarsC1, int nVarsC2 );
+extern unsigned     Fxu_PairHashKey( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2, int * pnBase, int * pnLits1, int * pnLits2 );
+extern unsigned     Fxu_PairHashKeyMv( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2, int * pnBase, int * pnLits1, int * pnLits2 );
+extern int          Fxu_PairCompare( Fxu_Pair * pPair1, Fxu_Pair * pPair2 );
+extern void         Fxu_PairAllocStorage( Fxu_Var * pVar, int nCubes );
+extern void         Fxu_PairFreeStorage( Fxu_Var * pVar );
+extern void         Fxu_PairClearStorage( Fxu_Cube * pCube );
+extern Fxu_Pair *   Fxu_PairAlloc( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2 );
+extern void         Fxu_PairAdd( Fxu_Pair * pPair );
+/*===== fxuSingle.c ====================================================*/
+extern void         Fxu_MatrixComputeSingles( Fxu_Matrix * p, int fUse0, int nSingleMax );
+extern void         Fxu_MatrixComputeSinglesOne( Fxu_Matrix * p, Fxu_Var * pVar );
+extern int          Fxu_SingleCountCoincidence( Fxu_Matrix * p, Fxu_Var * pVar1, Fxu_Var * pVar2 );
+/*===== fxuMatrix.c ====================================================*/
+// matrix
+extern Fxu_Matrix * Fxu_MatrixAllocate();
+extern void         Fxu_MatrixDelete( Fxu_Matrix * p );
+// double-cube divisor
+extern void         Fxu_MatrixAddDivisor( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2 );
+extern void         Fxu_MatrixDelDivisor( Fxu_Matrix * p, Fxu_Double * pDiv );
+// single-cube divisor
+extern void          Fxu_MatrixAddSingle( Fxu_Matrix * p, Fxu_Var * pVar1, Fxu_Var * pVar2, int Weight );
+// variable
+extern Fxu_Var *    Fxu_MatrixAddVar( Fxu_Matrix * p );
+// cube
+extern Fxu_Cube *   Fxu_MatrixAddCube( Fxu_Matrix * p, Fxu_Var * pVar, int iCube );
+// literal
+extern void         Fxu_MatrixAddLiteral( Fxu_Matrix * p, Fxu_Cube * pCube, Fxu_Var * pVar );
+extern void         Fxu_MatrixDelLiteral( Fxu_Matrix * p, Fxu_Lit * pLit );
+/*===== fxuList.c ====================================================*/
+// matrix -> variable 
+extern void         Fxu_ListMatrixAddVariable( Fxu_Matrix * p, Fxu_Var * pVar );
+extern void         Fxu_ListMatrixDelVariable( Fxu_Matrix * p, Fxu_Var * pVar );
+// matrix -> cube
+extern void         Fxu_ListMatrixAddCube( Fxu_Matrix * p, Fxu_Cube * pCube );
+extern void         Fxu_ListMatrixDelCube( Fxu_Matrix * p, Fxu_Cube * pCube );
+// matrix -> single
+extern void         Fxu_ListMatrixAddSingle( Fxu_Matrix * p, Fxu_Single * pSingle );
+extern void         Fxu_ListMatrixDelSingle( Fxu_Matrix * p, Fxu_Single * pSingle );
+// table -> divisor
+extern void         Fxu_ListTableAddDivisor( Fxu_Matrix * p, Fxu_Double * pDiv );
+extern void         Fxu_ListTableDelDivisor( Fxu_Matrix * p, Fxu_Double * pDiv );
+// cube -> literal 
+extern void         Fxu_ListCubeAddLiteral( Fxu_Cube * pCube, Fxu_Lit * pLit );
+extern void         Fxu_ListCubeDelLiteral( Fxu_Cube * pCube, Fxu_Lit * pLit );
+// var -> literal
+extern void         Fxu_ListVarAddLiteral( Fxu_Var * pVar, Fxu_Lit * pLit );
+extern void         Fxu_ListVarDelLiteral( Fxu_Var * pVar, Fxu_Lit * pLit );
+// divisor -> pair
+extern void         Fxu_ListDoubleAddPairLast( Fxu_Double * pDiv, Fxu_Pair * pLink );
+extern void         Fxu_ListDoubleAddPairFirst( Fxu_Double * pDiv, Fxu_Pair * pLink );
+extern void         Fxu_ListDoubleAddPairMiddle( Fxu_Double * pDiv, Fxu_Pair * pSpot, Fxu_Pair * pLink );
+extern void         Fxu_ListDoubleDelPair( Fxu_Double * pDiv, Fxu_Pair * pPair );
+/*===== fxuHeapDouble.c ====================================================*/
+extern Fxu_HeapDouble * Fxu_HeapDoubleStart();
+extern void         Fxu_HeapDoubleStop( Fxu_HeapDouble * p );
+extern void         Fxu_HeapDoublePrint( FILE * pFile, Fxu_HeapDouble * p );
+extern void         Fxu_HeapDoubleCheck( Fxu_HeapDouble * p );
+extern void         Fxu_HeapDoubleCheckOne( Fxu_HeapDouble * p, Fxu_Double * pDiv );
+
+extern void         Fxu_HeapDoubleInsert( Fxu_HeapDouble * p, Fxu_Double * pDiv );  
+extern void         Fxu_HeapDoubleUpdate( Fxu_HeapDouble * p, Fxu_Double * pDiv );  
+extern void         Fxu_HeapDoubleDelete( Fxu_HeapDouble * p, Fxu_Double * pDiv );  
+extern int          Fxu_HeapDoubleReadMaxWeight( Fxu_HeapDouble * p );  
+extern Fxu_Double * Fxu_HeapDoubleReadMax( Fxu_HeapDouble * p );  
+extern Fxu_Double * Fxu_HeapDoubleGetMax( Fxu_HeapDouble * p );  
+/*===== fxuHeapSingle.c ====================================================*/
+extern Fxu_HeapSingle * Fxu_HeapSingleStart();
+extern void         Fxu_HeapSingleStop( Fxu_HeapSingle * p );
+extern void         Fxu_HeapSinglePrint( FILE * pFile, Fxu_HeapSingle * p );
+extern void         Fxu_HeapSingleCheck( Fxu_HeapSingle * p );
+extern void         Fxu_HeapSingleCheckOne( Fxu_HeapSingle * p, Fxu_Single * pSingle );
+
+extern void         Fxu_HeapSingleInsert( Fxu_HeapSingle * p, Fxu_Single * pSingle );  
+extern void         Fxu_HeapSingleUpdate( Fxu_HeapSingle * p, Fxu_Single * pSingle );  
+extern void         Fxu_HeapSingleDelete( Fxu_HeapSingle * p, Fxu_Single * pSingle );  
+extern int          Fxu_HeapSingleReadMaxWeight( Fxu_HeapSingle * p );  
+extern Fxu_Single * Fxu_HeapSingleReadMax( Fxu_HeapSingle * p );
+extern Fxu_Single * Fxu_HeapSingleGetMax( Fxu_HeapSingle * p );  
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                         END OF FILE                              ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/fxu/fxuList.c b/src/opt/fxu/fxuList.c
new file mode 100644
index 00000000..52995804
--- /dev/null
+++ b/src/opt/fxu/fxuList.c
@@ -0,0 +1,522 @@
+/**CFile****************************************************************
+
+  FileName    [fxuList.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Operations on lists.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuList.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+// matrix -> var
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListMatrixAddVariable( Fxu_Matrix * p, Fxu_Var * pLink ) 
+{
+    Fxu_ListVar * pList = &p->lVars;
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pPrev = NULL;
+        pLink->pNext = NULL;
+    }
+    else
+    {
+        pLink->pNext = NULL;
+        pList->pTail->pNext = pLink;
+        pLink->pPrev = pList->pTail;
+        pList->pTail = pLink;
+    }
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListMatrixDelVariable( Fxu_Matrix * p, Fxu_Var * pLink )
+{
+    Fxu_ListVar * pList = &p->lVars;
+    if ( pList->pHead == pLink )
+         pList->pHead = pLink->pNext;
+    if ( pList->pTail == pLink )
+         pList->pTail = pLink->pPrev;
+    if ( pLink->pPrev )
+         pLink->pPrev->pNext = pLink->pNext;
+    if ( pLink->pNext )
+         pLink->pNext->pPrev = pLink->pPrev;
+    pList->nItems--;
+}
+
+
+// matrix -> cube
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListMatrixAddCube( Fxu_Matrix * p, Fxu_Cube * pLink )
+{
+    Fxu_ListCube * pList = &p->lCubes;
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pPrev = NULL;
+        pLink->pNext = NULL;
+    }
+    else
+    {
+        pLink->pNext = NULL;
+        pList->pTail->pNext = pLink;
+        pLink->pPrev = pList->pTail;
+        pList->pTail = pLink;
+    }
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListMatrixDelCube( Fxu_Matrix * p, Fxu_Cube * pLink )
+{
+    Fxu_ListCube * pList = &p->lCubes;
+    if ( pList->pHead == pLink )
+         pList->pHead = pLink->pNext;
+    if ( pList->pTail == pLink )
+         pList->pTail = pLink->pPrev;
+    if ( pLink->pPrev )
+         pLink->pPrev->pNext = pLink->pNext;
+    if ( pLink->pNext )
+         pLink->pNext->pPrev = pLink->pPrev;
+    pList->nItems--;
+}
+
+
+// matrix -> single
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListMatrixAddSingle( Fxu_Matrix * p, Fxu_Single * pLink )
+{
+    Fxu_ListSingle * pList = &p->lSingles;
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pPrev = NULL;
+        pLink->pNext = NULL;
+    }
+    else
+    {
+        pLink->pNext = NULL;
+        pList->pTail->pNext = pLink;
+        pLink->pPrev = pList->pTail;
+        pList->pTail = pLink;
+    }
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListMatrixDelSingle( Fxu_Matrix * p, Fxu_Single * pLink )
+{
+    Fxu_ListSingle * pList = &p->lSingles;
+    if ( pList->pHead == pLink )
+         pList->pHead = pLink->pNext;
+    if ( pList->pTail == pLink )
+         pList->pTail = pLink->pPrev;
+    if ( pLink->pPrev )
+         pLink->pPrev->pNext = pLink->pNext;
+    if ( pLink->pNext )
+         pLink->pNext->pPrev = pLink->pPrev;
+    pList->nItems--;
+}
+
+
+// table -> divisor
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListTableAddDivisor( Fxu_Matrix * p, Fxu_Double * pLink ) 
+{
+    Fxu_ListDouble * pList = &(p->pTable[pLink->Key]);
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pPrev = NULL;
+        pLink->pNext = NULL;
+    }
+    else
+    {
+        pLink->pNext = NULL;
+        pList->pTail->pNext = pLink;
+        pLink->pPrev = pList->pTail;
+        pList->pTail = pLink;
+    }
+    pList->nItems++;
+    p->nDivs++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListTableDelDivisor( Fxu_Matrix * p, Fxu_Double * pLink ) 
+{
+    Fxu_ListDouble * pList = &(p->pTable[pLink->Key]);
+    if ( pList->pHead == pLink )
+         pList->pHead = pLink->pNext;
+    if ( pList->pTail == pLink )
+         pList->pTail = pLink->pPrev;
+    if ( pLink->pPrev )
+         pLink->pPrev->pNext = pLink->pNext;
+    if ( pLink->pNext )
+         pLink->pNext->pPrev = pLink->pPrev;
+    pList->nItems--;
+    p->nDivs--;
+}
+
+
+// cube -> literal 
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListCubeAddLiteral( Fxu_Cube * pCube, Fxu_Lit * pLink )
+{
+    Fxu_ListLit * pList = &(pCube->lLits);
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pHPrev = NULL;
+        pLink->pHNext = NULL;
+    }
+    else
+    {
+        pLink->pHNext = NULL;
+        pList->pTail->pHNext = pLink;
+        pLink->pHPrev = pList->pTail;
+        pList->pTail = pLink;
+    }
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListCubeDelLiteral( Fxu_Cube * pCube, Fxu_Lit * pLink )
+{
+    Fxu_ListLit * pList = &(pCube->lLits);
+    if ( pList->pHead == pLink )
+         pList->pHead = pLink->pHNext;
+    if ( pList->pTail == pLink )
+         pList->pTail = pLink->pHPrev;
+    if ( pLink->pHPrev )
+         pLink->pHPrev->pHNext = pLink->pHNext;
+    if ( pLink->pHNext )
+         pLink->pHNext->pHPrev = pLink->pHPrev;
+    pList->nItems--;
+}
+
+
+// var -> literal
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListVarAddLiteral( Fxu_Var * pVar, Fxu_Lit * pLink )
+{
+    Fxu_ListLit * pList = &(pVar->lLits);
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pVPrev = NULL;
+        pLink->pVNext = NULL;
+    }
+    else
+    {
+        pLink->pVNext = NULL;
+        pList->pTail->pVNext = pLink;
+        pLink->pVPrev = pList->pTail;
+        pList->pTail = pLink;
+    }
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListVarDelLiteral( Fxu_Var * pVar, Fxu_Lit * pLink )
+{
+    Fxu_ListLit * pList = &(pVar->lLits);
+    if ( pList->pHead == pLink )
+         pList->pHead = pLink->pVNext;
+    if ( pList->pTail == pLink )
+         pList->pTail = pLink->pVPrev;
+    if ( pLink->pVPrev )
+         pLink->pVPrev->pVNext = pLink->pVNext;
+    if ( pLink->pVNext )
+         pLink->pVNext->pVPrev = pLink->pVPrev;
+    pList->nItems--;
+}
+
+
+
+// divisor -> pair
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListDoubleAddPairLast( Fxu_Double * pDiv, Fxu_Pair * pLink )
+{
+    Fxu_ListPair * pList = &pDiv->lPairs;
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pDPrev = NULL;
+        pLink->pDNext = NULL;
+    }
+    else
+    {
+        pLink->pDNext = NULL;
+        pList->pTail->pDNext = pLink;
+        pLink->pDPrev = pList->pTail;
+        pList->pTail = pLink;
+    }
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListDoubleAddPairFirst( Fxu_Double * pDiv, Fxu_Pair * pLink )
+{
+    Fxu_ListPair * pList = &pDiv->lPairs;
+    if ( pList->pHead == NULL )
+    {
+        pList->pHead = pLink;
+        pList->pTail = pLink;
+        pLink->pDPrev = NULL;
+        pLink->pDNext = NULL;
+    }
+    else
+    {
+        pLink->pDPrev = NULL;
+        pList->pHead->pDPrev = pLink;
+        pLink->pDNext = pList->pHead;
+        pList->pHead = pLink;
+    }
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the entry in the middle of the list after the spot.]
+
+  Description [Assumes that spot points to the link, after which the given
+  link should be added. Spot cannot be NULL or the tail of the list.
+  Therefore, the head and the tail of the list are not changed.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListDoubleAddPairMiddle( Fxu_Double * pDiv, Fxu_Pair * pSpot, Fxu_Pair * pLink )
+{
+    Fxu_ListPair * pList = &pDiv->lPairs;
+    assert( pSpot );
+    assert( pSpot != pList->pTail );
+    pLink->pDPrev = pSpot;
+    pLink->pDNext = pSpot->pDNext;
+    pLink->pDPrev->pDNext = pLink;
+    pLink->pDNext->pDPrev = pLink;
+    pList->nItems++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListDoubleDelPair( Fxu_Double * pDiv, Fxu_Pair * pLink )
+{
+    Fxu_ListPair * pList = &pDiv->lPairs;
+    if ( pList->pHead == pLink )
+         pList->pHead = pLink->pDNext;
+    if ( pList->pTail == pLink )
+         pList->pTail = pLink->pDPrev;
+    if ( pLink->pDPrev )
+         pLink->pDPrev->pDNext = pLink->pDNext;
+    if ( pLink->pDNext )
+         pLink->pDNext->pDPrev = pLink->pDPrev;
+    pList->nItems--;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_ListDoubleAddPairPlace( Fxu_Double * pDiv, Fxu_Pair * pPair, Fxu_Pair * pPairSpot )
+{
+    printf( "Fxu_ListDoubleAddPairPlace() is called!\n" );
+}
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuMatrix.c b/src/opt/fxu/fxuMatrix.c
new file mode 100644
index 00000000..93ec7b90
--- /dev/null
+++ b/src/opt/fxu/fxuMatrix.c
@@ -0,0 +1,374 @@
+/**CFile****************************************************************
+
+  FileName    [fxuMatrix.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Procedures to manipulate the sparse matrix.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuMatrix.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+extern unsigned int Cudd_Prime( unsigned int p );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Matrix * Fxu_MatrixAllocate()
+{
+    Fxu_Matrix * p;
+    p = ALLOC( Fxu_Matrix, 1 );
+    memset( p, 0, sizeof(Fxu_Matrix) );
+    p->nTableSize = Cudd_Prime(10000);
+    p->pTable = ALLOC( Fxu_ListDouble, p->nTableSize );
+    memset( p->pTable, 0, sizeof(Fxu_ListDouble) * p->nTableSize );
+#ifndef USE_SYSTEM_MEMORY_MANAGEMENT
+    {
+        // get the largest size in bytes for the following structures:
+        // Fxu_Cube, Fxu_Var, Fxu_Lit, Fxu_Pair, Fxu_Double, Fxu_Single
+        // (currently, Fxu_Var, Fxu_Pair, Fxu_Double take 10 machine words)
+        int nSizeMax, nSizeCur;
+        nSizeMax = -1;
+        nSizeCur = sizeof(Fxu_Cube);
+        if ( nSizeMax < nSizeCur )
+             nSizeMax = nSizeCur;
+        nSizeCur = sizeof(Fxu_Var);
+        if ( nSizeMax < nSizeCur )
+             nSizeMax = nSizeCur;
+        nSizeCur = sizeof(Fxu_Lit);
+        if ( nSizeMax < nSizeCur )
+             nSizeMax = nSizeCur;
+        nSizeCur = sizeof(Fxu_Pair);
+        if ( nSizeMax < nSizeCur )
+             nSizeMax = nSizeCur;
+        nSizeCur = sizeof(Fxu_Double);
+        if ( nSizeMax < nSizeCur )
+             nSizeMax = nSizeCur;
+        nSizeCur = sizeof(Fxu_Single);
+        if ( nSizeMax < nSizeCur )
+             nSizeMax = nSizeCur;
+        p->pMemMan  = Extra_MmFixedStart( nSizeMax ); 
+    }
+#endif
+    p->pHeapDouble = Fxu_HeapDoubleStart();
+    p->pHeapSingle = Fxu_HeapSingleStart();
+    p->vPairs = Vec_PtrAlloc( 100 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixDelete( Fxu_Matrix * p )
+{
+    Fxu_HeapDoubleCheck( p->pHeapDouble );
+    Fxu_HeapDoubleStop( p->pHeapDouble );
+    Fxu_HeapSingleStop( p->pHeapSingle );
+
+    // delete other things
+#ifdef USE_SYSTEM_MEMORY_MANAGEMENT
+    // this code is not needed when the custom memory manager is used
+    {
+        Fxu_Cube * pCube, * pCube2;
+        Fxu_Var * pVar, * pVar2;
+        Fxu_Lit * pLit, * pLit2;
+        Fxu_Double * pDiv, * pDiv2;
+        Fxu_Single * pSingle, * pSingle2;
+        Fxu_Pair * pPair, * pPair2;
+        int i;
+        // delete the divisors
+        Fxu_MatrixForEachDoubleSafe( p, pDiv, pDiv2, i )
+        {
+            Fxu_DoubleForEachPairSafe( pDiv, pPair, pPair2 )
+                MEM_FREE_FXU( p, Fxu_Pair, 1, pPair );
+               MEM_FREE_FXU( p, Fxu_Double, 1, pDiv );
+        }
+        Fxu_MatrixForEachSingleSafe( p, pSingle, pSingle2 )
+               MEM_FREE_FXU( p, Fxu_Single, 1, pSingle );
+        // delete the entries
+        Fxu_MatrixForEachCube( p, pCube )
+            Fxu_CubeForEachLiteralSafe( pCube, pLit, pLit2 )
+                MEM_FREE_FXU( p, Fxu_Lit, 1, pLit );
+        // delete the cubes
+        Fxu_MatrixForEachCubeSafe( p, pCube, pCube2 )
+            MEM_FREE_FXU( p, Fxu_Cube, 1, pCube );
+        // delete the vars
+        Fxu_MatrixForEachVariableSafe( p, pVar, pVar2 )
+            MEM_FREE_FXU( p, Fxu_Var, 1, pVar );
+    }
+#else
+    Extra_MmFixedStop( p->pMemMan );
+#endif
+
+    Vec_PtrFree( p->vPairs );
+    FREE( p->pppPairs );
+    FREE( p->ppPairs );
+//    FREE( p->pPairsTemp );
+    FREE( p->pTable );
+    FREE( p->ppVars );
+    FREE( p );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Adds a variable to the matrix.]
+
+  Description [This procedure always adds variables at the end of the matrix.
+  It assigns the var's node and number. It adds the var to the linked list of
+  all variables and to the table of all nodes.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Var * Fxu_MatrixAddVar( Fxu_Matrix * p )
+{
+    Fxu_Var * pVar;
+    pVar = MEM_ALLOC_FXU( p, Fxu_Var, 1 );
+    memset( pVar, 0, sizeof(Fxu_Var) );
+    pVar->iVar = p->lVars.nItems;
+    p->ppVars[pVar->iVar] = pVar;
+    Fxu_ListMatrixAddVariable( p, pVar );
+    return pVar;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds a literal to the matrix.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Cube * Fxu_MatrixAddCube( Fxu_Matrix * p, Fxu_Var * pVar, int iCube )
+{
+    Fxu_Cube * pCube;
+    pCube = MEM_ALLOC_FXU( p, Fxu_Cube, 1 );
+    memset( pCube, 0, sizeof(Fxu_Cube) );
+    pCube->pVar  = pVar;
+    pCube->iCube = iCube;
+    Fxu_ListMatrixAddCube( p, pCube );
+    return pCube;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds a literal to the matrix.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixAddLiteral( Fxu_Matrix * p, Fxu_Cube * pCube, Fxu_Var * pVar )
+{
+    Fxu_Lit * pLit;
+    pLit = MEM_ALLOC_FXU( p, Fxu_Lit, 1 );
+    memset( pLit, 0, sizeof(Fxu_Lit) );
+    // insert the literal into two linked lists
+    Fxu_ListCubeAddLiteral( pCube, pLit );
+    Fxu_ListVarAddLiteral( pVar, pLit );
+    // set the back pointers
+    pLit->pCube = pCube;
+    pLit->pVar  = pVar;
+    pLit->iCube = pCube->iCube;
+    pLit->iVar  = pVar->iVar;
+    // increment the literal counter
+    p->nEntries++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deletes the divisor from the matrix.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixDelDivisor( Fxu_Matrix * p, Fxu_Double * pDiv )
+{
+    // delete divisor from the table
+    Fxu_ListTableDelDivisor( p, pDiv );
+    // recycle the divisor
+    MEM_FREE_FXU( p, Fxu_Double, 1, pDiv );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deletes the literal fromthe matrix.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixDelLiteral( Fxu_Matrix * p, Fxu_Lit * pLit )
+{
+    // delete the literal
+    Fxu_ListCubeDelLiteral( pLit->pCube, pLit );
+    Fxu_ListVarDelLiteral( pLit->pVar, pLit );
+    MEM_FREE_FXU( p, Fxu_Lit, 1, pLit );
+    // increment the literal counter
+    p->nEntries--;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Creates and adds a single cube divisor.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixAddSingle( Fxu_Matrix * p, Fxu_Var * pVar1, Fxu_Var * pVar2, int Weight )
+{
+    Fxu_Single * pSingle;
+    assert( pVar1->iVar < pVar2->iVar );
+    pSingle = MEM_ALLOC_FXU( p, Fxu_Single, 1 );
+    memset( pSingle, 0, sizeof(Fxu_Single) );
+    pSingle->Num = p->lSingles.nItems;
+    pSingle->Weight = Weight;
+    pSingle->HNum = 0;
+    pSingle->pVar1 = pVar1;
+    pSingle->pVar2 = pVar2;
+    Fxu_ListMatrixAddSingle( p, pSingle );
+    // add to the heap
+    Fxu_HeapSingleInsert( p->pHeapSingle, pSingle );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixAddDivisor( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2 )
+{
+    Fxu_Pair * pPair;
+    Fxu_Double * pDiv;
+    int nBase, nLits1, nLits2;
+    int fFound;
+    unsigned Key;
+
+    // canonicize the pair
+    Fxu_PairCanonicize( &pCube1, &pCube2 );
+    // compute the hash key
+    Key = Fxu_PairHashKey( p, pCube1, pCube2, &nBase, &nLits1, &nLits2 );
+
+    // create the cube pair
+    pPair = Fxu_PairAlloc( p, pCube1, pCube2 );
+    pPair->nBase  = nBase;
+    pPair->nLits1 = nLits1;
+    pPair->nLits2 = nLits2;
+
+    // check if the divisor for this pair already exists
+    fFound = 0;
+    Key %= p->nTableSize;
+    Fxu_TableForEachDouble( p, Key, pDiv )
+    {
+        if ( Fxu_PairCompare( pPair, pDiv->lPairs.pTail ) ) // they are equal
+        {
+            fFound = 1;
+            break;
+        }
+    }
+
+    if ( !fFound )
+    {   // create the new divisor
+        pDiv = MEM_ALLOC_FXU( p, Fxu_Double, 1 );
+        memset( pDiv, 0, sizeof(Fxu_Double) );
+        pDiv->Key = Key;
+        // set the number of this divisor
+        pDiv->Num = p->nDivsTotal++; // p->nDivs;
+        // insert the divisor in the table
+        Fxu_ListTableAddDivisor( p, pDiv );
+        // set the initial cost of the divisor
+        pDiv->Weight -= pPair->nLits1 + pPair->nLits2;
+    }
+
+    // link the pair to the cubes
+    Fxu_PairAdd( pPair );
+    // connect the pair and the divisor
+    pPair->pDiv = pDiv;
+    Fxu_ListDoubleAddPairLast( pDiv, pPair );    
+    // update the max number of pairs in a divisor
+//    if ( p->nPairsMax < pDiv->lPairs.nItems )
+//        p->nPairsMax = pDiv->lPairs.nItems;
+    // update the divisor's weight
+    pDiv->Weight += pPair->nLits1 + pPair->nLits2 - 1 + pPair->nBase;
+    if ( fFound ) // update the divisor in the heap
+        Fxu_HeapDoubleUpdate( p->pHeapDouble, pDiv );
+    else  // add the new divisor to the heap
+        Fxu_HeapDoubleInsert( p->pHeapDouble, pDiv );
+}
+
+/*
+    {
+        int piVarsC1[100], piVarsC2[100], nVarsC1, nVarsC2;
+        Fxu_Double * pDivCur;
+        Fxu_MatrixGetDoubleVars( p, pDiv, piVarsC1, piVarsC2, &nVarsC1, &nVarsC2 );
+        pDivCur = Fxu_MatrixFindDouble( p, piVarsC1, piVarsC2, nVarsC1, nVarsC2 );
+        assert( pDivCur == pDiv );
+    }
+*/
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuPair.c b/src/opt/fxu/fxuPair.c
new file mode 100644
index 00000000..3c031ce8
--- /dev/null
+++ b/src/opt/fxu/fxuPair.c
@@ -0,0 +1,555 @@
+/**CFile****************************************************************
+
+  FileName    [fxuPair.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Operations on cube pairs.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuPair.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define MAX_PRIMES      304
+
+static s_Primes[MAX_PRIMES] =
+{
+    2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 
+    41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 
+    97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 
+    157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 
+    227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 
+    283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 
+    367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 
+    439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 
+    509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 
+    599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 
+    661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 
+    751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 
+    829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 
+    919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997, 
+    1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 
+    1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 
+    1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 
+    1259, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 
+    1327, 1361, 1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 
+    1447, 1451, 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 
+    1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 
+    1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667, 1669, 1693, 
+    1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759, 1777, 1783, 
+    1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 
+    1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987, 
+    1993, 1997, 1999, 2003 
+};
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Find the canonical permutation of two cubes in the pair.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_PairCanonicize( Fxu_Cube ** ppCube1, Fxu_Cube ** ppCube2 )
+{
+    Fxu_Lit * pLit1, * pLit2;
+    Fxu_Cube * pCubeTemp;
+
+    // walk through the cubes to determine 
+    // the one that has higher first variable
+    pLit1 = (*ppCube1)->lLits.pHead;
+    pLit2 = (*ppCube2)->lLits.pHead;
+    while ( 1 )
+    {
+        if ( pLit1->iVar == pLit2->iVar )
+        {
+            pLit1 = pLit1->pHNext;
+            pLit2 = pLit2->pHNext;
+            continue;
+        }
+        assert( pLit1 && pLit2 ); // this is true if the covers are SCC-free
+        if ( pLit1->iVar > pLit2->iVar )
+        { // swap the cubes
+            pCubeTemp = *ppCube1;
+            *ppCube1  = *ppCube2;
+            *ppCube2  = pCubeTemp;
+        }
+        break;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find the canonical permutation of two cubes in the pair.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_PairCanonicize2( Fxu_Cube ** ppCube1, Fxu_Cube ** ppCube2 )
+{
+    Fxu_Cube * pCubeTemp;
+    // canonicize the pair by ordering the cubes
+    if ( (*ppCube1)->iCube > (*ppCube2)->iCube )
+    { // swap the cubes
+        pCubeTemp = *ppCube1;
+        *ppCube1  = *ppCube2;
+        *ppCube2  = pCubeTemp;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Fxu_PairHashKeyArray( Fxu_Matrix * p, int piVarsC1[], int piVarsC2[], int nVarsC1, int nVarsC2 )
+{
+    int Offset1 = 100, Offset2 = 200, i;
+    unsigned Key;
+    // compute the hash key
+    Key = 0;
+    for ( i = 0; i < nVarsC1; i++ )
+        Key ^= s_Primes[Offset1+i] * piVarsC1[i];
+    for ( i = 0; i < nVarsC2; i++ )
+        Key ^= s_Primes[Offset2+i] * piVarsC2[i];
+    return Key;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the hash key of the divisor represented by the pair of cubes.]
+
+  Description [Goes through the variables in both cubes. Skips the identical
+  ones (this corresponds to making the cubes cube-free). Computes the hash 
+  value of the cubes. Assigns the number of literals in the base and in the 
+  cubes without base.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Fxu_PairHashKey( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2, 
+                         int * pnBase, int * pnLits1, int * pnLits2 )
+{
+    int Offset1 = 100, Offset2 = 200;
+    int nBase, nLits1, nLits2;
+    Fxu_Lit * pLit1, * pLit2;
+    unsigned Key;
+
+    // compute the hash key
+    Key    = 0;
+    nLits1 = 0;
+    nLits2 = 0;
+    nBase  = 0;
+    pLit1  = pCube1->lLits.pHead;
+    pLit2  = pCube2->lLits.pHead;
+    while ( 1 )
+    {
+        if ( pLit1 && pLit2 )
+        {
+            if ( pLit1->iVar == pLit2->iVar )
+            { // ensure cube-free
+                pLit1 = pLit1->pHNext;
+                pLit2 = pLit2->pHNext;
+                // add this literal to the base
+                nBase++;
+            }
+            else if ( pLit1->iVar < pLit2->iVar )
+            {
+                Key  ^= s_Primes[Offset1+nLits1] * pLit1->iVar;
+                pLit1 = pLit1->pHNext;
+                nLits1++;
+            }
+            else
+            {
+                Key  ^= s_Primes[Offset2+nLits2] * pLit2->iVar;
+                pLit2 = pLit2->pHNext;
+                nLits2++;
+            }
+        }
+        else if ( pLit1 && !pLit2 )
+        {
+            Key  ^= s_Primes[Offset1+nLits1] * pLit1->iVar;
+            pLit1 = pLit1->pHNext;
+            nLits1++;
+        }
+        else if ( !pLit1 && pLit2 )
+        {
+            Key  ^= s_Primes[Offset2+nLits2] * pLit2->iVar;
+            pLit2 = pLit2->pHNext;
+            nLits2++;
+        }
+        else
+            break;
+    }
+    *pnBase  = nBase;
+    *pnLits1 = nLits1;
+    *pnLits2 = nLits2;
+    return Key;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compares the two pairs.]
+
+  Description [Returns 1 if the divisors represented by these pairs
+  are equal.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_PairCompare( Fxu_Pair * pPair1, Fxu_Pair * pPair2 )
+{
+    Fxu_Lit * pD1C1, * pD1C2;
+    Fxu_Lit * pD2C1, * pD2C2;
+    int TopVar1, TopVar2;
+    int Code;
+
+    if ( pPair1->nLits1 != pPair2->nLits1 )
+        return 0;
+    if ( pPair1->nLits2 != pPair2->nLits2 )
+        return 0;
+
+    pD1C1 = pPair1->pCube1->lLits.pHead;
+    pD1C2 = pPair1->pCube2->lLits.pHead;
+
+    pD2C1 = pPair2->pCube1->lLits.pHead;
+    pD2C2 = pPair2->pCube2->lLits.pHead;
+
+    Code  = pD1C1? 8: 0;
+    Code |= pD1C2? 4: 0;
+    Code |= pD2C1? 2: 0;
+    Code |= pD2C2? 1: 0;
+    assert( Code == 15 );
+
+    while ( 1 )
+    {
+        switch ( Code )
+        {
+        case 0:  // -- --      NULL   NULL     NULL   NULL 
+            return 1;
+        case 1:  // -- -1      NULL   NULL     NULL   pD2C2
+            return 0;
+        case 2:  // -- 1-      NULL   NULL     pD2C1  NULL 
+            return 0;
+        case 3:  // -- 11      NULL   NULL     pD2C1  pD2C2
+            if ( pD2C1->iVar != pD2C2->iVar )
+                return 0;
+            pD2C1 = pD2C1->pHNext;
+            pD2C2 = pD2C2->pHNext;
+            break;
+        case 4:  // -1 --      NULL   pD1C2    NULL   NULL 
+            return 0;
+        case 5:  // -1 -1      NULL   pD1C2    NULL   pD2C2
+            if ( pD1C2->iVar != pD2C2->iVar )
+                return 0;
+            pD1C2 = pD1C2->pHNext;
+            pD2C2 = pD2C2->pHNext;
+            break;
+        case 6:  // -1 1-      NULL   pD1C2    pD2C1  NULL 
+            return 0;
+        case 7:  // -1 11      NULL   pD1C2    pD2C1  pD2C2
+            TopVar2 = Fxu_Min( pD2C1->iVar, pD2C2->iVar );
+            if ( TopVar2 == pD1C2->iVar )
+            {
+                if ( pD2C1->iVar <= pD2C2->iVar )
+                    return 0;
+                pD1C2 = pD1C2->pHNext;
+                pD2C2 = pD2C2->pHNext;
+            }
+            else if ( TopVar2 < pD1C2->iVar )
+            {
+                if ( pD2C1->iVar != pD2C2->iVar )
+                    return 0;
+                pD2C1 = pD2C1->pHNext;
+                pD2C2 = pD2C2->pHNext;
+            }
+            else
+                return 0;
+            break;
+        case 8:  // 1- --      pD1C1  NULL     NULL   NULL 
+            return 0;
+        case 9:  // 1- -1      pD1C1  NULL     NULL   pD2C2
+            return 0;
+        case 10: // 1- 1-      pD1C1  NULL     pD2C1  NULL 
+            if ( pD1C1->iVar != pD2C1->iVar )
+                return 0;
+            pD1C1 = pD1C1->pHNext;
+            pD2C1 = pD2C1->pHNext;
+            break;
+        case 11: // 1- 11      pD1C1  NULL     pD2C1  pD2C2
+            TopVar2 = Fxu_Min( pD2C1->iVar, pD2C2->iVar );
+            if ( TopVar2 == pD1C1->iVar )
+            {
+                if ( pD2C1->iVar >= pD2C2->iVar )
+                    return 0;
+                pD1C1 = pD1C1->pHNext;
+                pD2C1 = pD2C1->pHNext;
+            }
+            else if ( TopVar2 < pD1C1->iVar )
+            {
+                if ( pD2C1->iVar != pD2C2->iVar )
+                    return 0;
+                pD2C1 = pD2C1->pHNext;
+                pD2C2 = pD2C2->pHNext;
+            }
+            else
+                return 0;
+            break;
+        case 12: // 11 --      pD1C1  pD1C2    NULL   NULL 
+            if ( pD1C1->iVar != pD1C2->iVar )
+                return 0;
+            pD1C1 = pD1C1->pHNext;
+            pD1C2 = pD1C2->pHNext;
+            break;
+        case 13: // 11 -1      pD1C1  pD1C2    NULL   pD2C2
+            TopVar1 = Fxu_Min( pD1C1->iVar, pD1C2->iVar );
+            if ( TopVar1 == pD2C2->iVar )
+            {
+                if ( pD1C1->iVar <= pD1C2->iVar )
+                    return 0;
+                pD1C2 = pD1C2->pHNext;
+                pD2C2 = pD2C2->pHNext;
+            }
+            else if ( TopVar1 < pD2C2->iVar )
+            {
+                if ( pD1C1->iVar != pD1C2->iVar )
+                    return 0;
+                pD1C1 = pD1C1->pHNext;
+                pD1C2 = pD1C2->pHNext;
+            }
+            else
+                return 0;
+            break;
+        case 14: // 11 1-      pD1C1  pD1C2    pD2C1  NULL 
+            TopVar1 = Fxu_Min( pD1C1->iVar, pD1C2->iVar );
+            if ( TopVar1 == pD2C1->iVar )
+            {
+                if ( pD1C1->iVar >= pD1C2->iVar )
+                    return 0;
+                pD1C1 = pD1C1->pHNext;
+                pD2C1 = pD2C1->pHNext;
+            }
+            else if ( TopVar1 < pD2C1->iVar )
+            {
+                if ( pD1C1->iVar != pD1C2->iVar )
+                    return 0;
+                pD1C1 = pD1C1->pHNext;
+                pD1C2 = pD1C2->pHNext;
+            }
+            else
+                return 0;
+            break;
+        case 15: // 11 11      pD1C1  pD1C2    pD2C1  pD2C2
+            TopVar1 = Fxu_Min( pD1C1->iVar, pD1C2->iVar );
+            TopVar2 = Fxu_Min( pD2C1->iVar, pD2C2->iVar );
+            if ( TopVar1 == TopVar2 )
+            {
+                if ( pD1C1->iVar == pD1C2->iVar )
+                {
+                    if ( pD2C1->iVar != pD2C2->iVar )
+                        return 0;
+                    pD1C1 = pD1C1->pHNext;
+                    pD1C2 = pD1C2->pHNext;
+                    pD2C1 = pD2C1->pHNext;
+                    pD2C2 = pD2C2->pHNext;
+                }
+                else
+                {
+                    if ( pD2C1->iVar == pD2C2->iVar )
+                        return 0;
+                    if ( pD1C1->iVar < pD1C2->iVar )
+                    {
+                        if ( pD2C1->iVar > pD2C2->iVar )
+                            return 0;
+                        pD1C1 = pD1C1->pHNext;
+                        pD2C1 = pD2C1->pHNext;
+                    }
+                    else
+                    {
+                        if ( pD2C1->iVar < pD2C2->iVar )
+                            return 0;
+                        pD1C2 = pD1C2->pHNext;
+                        pD2C2 = pD2C2->pHNext;
+                    }
+                }
+            }
+            else if ( TopVar1 < TopVar2 )
+            {
+                if ( pD1C1->iVar != pD1C2->iVar )
+                    return 0;
+                pD1C1 = pD1C1->pHNext;
+                pD1C2 = pD1C2->pHNext;
+            }
+            else 
+            {
+                if ( pD2C1->iVar != pD2C2->iVar )
+                    return 0;
+                pD2C1 = pD2C1->pHNext;
+                pD2C2 = pD2C2->pHNext;
+            }
+            break;
+        default:
+            assert( 0 );
+            break;
+        }
+
+        Code  = pD1C1? 8: 0;
+        Code |= pD1C2? 4: 0;
+        Code |= pD2C1? 2: 0;
+        Code |= pD2C2? 1: 0;
+    }
+    return 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates the storage for cubes pairs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_PairAllocStorage( Fxu_Var * pVar, int nCubes )
+{
+    int k;
+//    assert( pVar->nCubes == 0 );
+    pVar->nCubes  = nCubes;
+    // allocate memory for all the pairs
+    pVar->ppPairs    = ALLOC( Fxu_Pair **, nCubes );
+    pVar->ppPairs[0] = ALLOC( Fxu_Pair *,  nCubes * nCubes );
+    memset( pVar->ppPairs[0], 0, sizeof(Fxu_Pair *) * nCubes * nCubes );
+    for ( k = 1; k < nCubes; k++ )
+        pVar->ppPairs[k] = pVar->ppPairs[k-1] + nCubes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Clears all pairs associated with this cube.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_PairClearStorage( Fxu_Cube * pCube )
+{
+    Fxu_Var * pVar;
+    int i;
+    pVar = pCube->pVar;
+    for ( i = 0; i < pVar->nCubes; i++ )
+    {
+        pVar->ppPairs[pCube->iCube][i] = NULL;
+        pVar->ppPairs[i][pCube->iCube] = NULL;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Clears all pairs associated with this cube.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_PairFreeStorage( Fxu_Var * pVar )
+{
+    if ( pVar->ppPairs )
+    {
+        FREE( pVar->ppPairs[0] );
+        FREE( pVar->ppPairs );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the pair to storage.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Pair * Fxu_PairAlloc( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2 )
+{
+    Fxu_Pair * pPair;
+       assert( pCube1->pVar == pCube2->pVar );
+    pPair = MEM_ALLOC_FXU( p, Fxu_Pair, 1 );
+    memset( pPair, 0, sizeof(Fxu_Pair) );
+    pPair->pCube1 = pCube1;
+    pPair->pCube2 = pCube2;
+    pPair->iCube1 = pCube1->iCube;
+    pPair->iCube2 = pCube2->iCube;
+    return pPair;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the pair to storage.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_PairAdd( Fxu_Pair * pPair )
+{
+    Fxu_Var * pVar;
+
+    pVar = pPair->pCube1->pVar;
+    assert( pVar == pPair->pCube2->pVar );
+
+    pVar->ppPairs[pPair->iCube1][pPair->iCube2] = pPair;
+    pVar->ppPairs[pPair->iCube2][pPair->iCube1] = pPair;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuPrint.c b/src/opt/fxu/fxuPrint.c
new file mode 100644
index 00000000..232b109a
--- /dev/null
+++ b/src/opt/fxu/fxuPrint.c
@@ -0,0 +1,195 @@
+/**CFile****************************************************************
+
+  FileName    [fxuPrint.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Various printing procedures.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuPrint.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixPrint( FILE * pFile, Fxu_Matrix * p )
+{
+    Fxu_Var * pVar;
+    Fxu_Cube * pCube;
+    Fxu_Double * pDiv;
+    Fxu_Single * pSingle;
+    Fxu_Lit * pLit;
+    Fxu_Pair * pPair;
+    int i, LastNum;
+    int fStdout;
+
+    fStdout = 1;
+    if ( pFile == NULL )
+    {
+        pFile = fopen( "matrix.txt", "w" );
+        fStdout = 0;
+    }
+
+    fprintf( pFile, "Matrix has %d vars, %d cubes, %d literals, %d divisors.\n", 
+        p->lVars.nItems, p->lCubes.nItems, p->nEntries, p->nDivs );
+    fprintf( pFile, "Divisors selected so far: single = %d, double = %d.\n", 
+        p->nDivs1, p->nDivs2 );
+    fprintf( pFile, "\n" );
+
+    // print the numbers on top of the matrix
+    for ( i = 0; i < 12; i++ )
+        fprintf( pFile, " " );
+    Fxu_MatrixForEachVariable( p, pVar )
+        fprintf( pFile, "%d", pVar->iVar % 10 );
+    fprintf( pFile, "\n" );
+
+    // print the rows
+    Fxu_MatrixForEachCube( p, pCube )
+    {
+        fprintf( pFile, "%4d", pCube->iCube );
+        fprintf( pFile, "  " );
+        fprintf( pFile, "%4d", pCube->pVar->iVar );
+        fprintf( pFile, "  " );
+
+        // print the literals
+        LastNum = -1;
+        Fxu_CubeForEachLiteral( pCube, pLit )
+        {
+            for ( i = LastNum + 1; i < pLit->pVar->iVar; i++ )
+                fprintf( pFile, "." );
+            fprintf( pFile, "1" );
+            LastNum = i;
+        }
+        for ( i = LastNum + 1; i < p->lVars.nItems; i++ )
+            fprintf( pFile, "." );
+        fprintf( pFile, "\n" );
+    }
+    fprintf( pFile, "\n" );
+
+    // print the double-cube divisors
+    fprintf( pFile, "The double divisors are:\n" );
+    Fxu_MatrixForEachDouble( p, pDiv, i )
+    {
+        fprintf( pFile, "Divisor #%3d (lit=%d,%d) (w=%2d):  ", 
+            pDiv->Num, pDiv->lPairs.pHead->nLits1, 
+            pDiv->lPairs.pHead->nLits2, pDiv->Weight );
+        Fxu_DoubleForEachPair( pDiv, pPair )
+            fprintf( pFile, " <%d, %d> (b=%d)", 
+                pPair->pCube1->iCube, pPair->pCube2->iCube, pPair->nBase );
+        fprintf( pFile, "\n" );
+    }
+    fprintf( pFile, "\n" );
+
+    // print the divisors associated with each cube
+    fprintf( pFile, "The cubes are:\n" );
+    Fxu_MatrixForEachCube( p, pCube )
+    {
+        fprintf( pFile, "Cube #%3d: ", pCube->iCube );
+        if ( pCube->pVar->ppPairs )
+            Fxu_CubeForEachPair( pCube, pPair, i )
+                fprintf( pFile, " <%d %d> (d=%d) (b=%d)", 
+                    pPair->iCube1, pPair->iCube2, pPair->pDiv->Num, pPair->nBase );
+        fprintf( pFile, "\n" );
+    }
+    fprintf( pFile, "\n" );
+
+    // print the single-cube divisors
+    fprintf( pFile, "The single divisors are:\n" );
+    Fxu_MatrixForEachSingle( p, pSingle )
+    {
+        fprintf( pFile, "Single-cube divisor #%5d: Var1 = %4d. Var2 = %4d. Weight = %2d\n", 
+            pSingle->Num, pSingle->pVar1->iVar, pSingle->pVar2->iVar, pSingle->Weight );
+    }
+    fprintf( pFile, "\n" );
+
+/*
+    {
+        int Index;
+        fprintf( pFile, "Distribution of divisors in the hash table:\n" );
+        for ( Index = 0; Index < p->nTableSize; Index++ )
+            fprintf( pFile, " %d", p->pTable[Index].nItems );
+        fprintf( pFile, "\n" );
+    }
+*/
+    if ( !fStdout )
+        fclose( pFile );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixPrintDivisorProfile( FILE * pFile, Fxu_Matrix * p )
+{
+    Fxu_Double * pDiv;
+    int WeightMax;
+    int * pProfile;
+    int Counter1; // the number of -1 weight
+    int CounterL; // the number of less than -1 weight
+    int i;
+
+    WeightMax = Fxu_HeapDoubleReadMaxWeight( p->pHeapDouble );
+    pProfile = ALLOC( int, (WeightMax + 1) );
+    memset( pProfile, 0, sizeof(int) * (WeightMax + 1) );
+
+    Counter1 = 0;
+    CounterL = 0;
+    Fxu_MatrixForEachDouble( p, pDiv, i )
+    {
+        assert( pDiv->Weight <= WeightMax );
+        if ( pDiv->Weight == -1 )
+            Counter1++;
+        else if ( pDiv->Weight < 0 )
+            CounterL++;
+        else
+            pProfile[ pDiv->Weight ]++;
+    }
+
+    fprintf( pFile, "The double divisors profile:\n" );
+    fprintf( pFile, "Weight  < -1 divisors = %6d\n", CounterL );
+    fprintf( pFile, "Weight    -1 divisors = %6d\n", Counter1 );
+    for ( i = 0; i <= WeightMax; i++ )
+        if ( pProfile[i] )
+            fprintf( pFile, "Weight   %3d divisors = %6d\n", i, pProfile[i] );
+    fprintf( pFile, "End of divisor profile printout\n" );
+    FREE( pProfile );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuReduce.c b/src/opt/fxu/fxuReduce.c
new file mode 100644
index 00000000..0ab8a157
--- /dev/null
+++ b/src/opt/fxu/fxuReduce.c
@@ -0,0 +1,204 @@
+/**CFile****************************************************************
+
+  FileName    [fxuReduce.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Procedures to reduce the number of considered cube pairs.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuReduce.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "fxuInt.h"
+#include "fxu.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Fxu_CountPairDiffs( char * pCover, unsigned char pDiffs[] );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Precomputes the pairs to use for creating two-cube divisors.]
+
+  Description [This procedure takes the matrix with variables and cubes 
+  allocated (p), the original covers of the nodes (i-sets) and their number 
+  (ppCovers,nCovers). The maximum number of pairs to compute and the total 
+  number of pairs in existence. This procedure adds to the storage of
+  divisors exactly the given number of pairs (nPairsMax) while taking
+  first those pairs that have the smallest number of literals in their
+  cube-free form.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_PreprocessCubePairs( Fxu_Matrix * p, Vec_Ptr_t * vCovers, int nPairsTotal, int nPairsMax )
+{
+    unsigned char * pnLitsDiff;   // storage for the counters of diff literals
+    int * pnPairCounters;         // the counters of pairs for each number of diff literals
+    Fxu_Cube * pCubeFirst, * pCubeLast;
+    Fxu_Cube * pCube1, * pCube2;
+    Fxu_Var * pVar;
+    int nCubes, nBitsMax, nSum;
+    int CutOffNum, CutOffQuant;
+    int iPair, iQuant, k, c;
+    int clk = clock();
+    char * pSopCover;
+    int nFanins;
+
+    assert( nPairsMax < nPairsTotal );
+
+    // allocate storage for counter of diffs
+    pnLitsDiff = ALLOC( unsigned char, nPairsTotal );
+    // go through the covers and precompute the distances between the pairs
+    iPair    =  0;
+    nBitsMax = -1;
+    for ( c = 0; c < vCovers->nSize; c++ )
+        if ( pSopCover = vCovers->pArray[c] )
+        {
+            nFanins = Abc_SopGetVarNum(pSopCover);
+            // precompute the differences
+            Fxu_CountPairDiffs( pSopCover, pnLitsDiff + iPair );
+            // update the counter
+            nCubes = Abc_SopGetCubeNum( pSopCover );
+            iPair += nCubes * (nCubes - 1) / 2;
+            if ( nBitsMax < nFanins )
+                nBitsMax = nFanins;
+        }
+    assert( iPair == nPairsTotal );
+
+    // allocate storage for counters of cube pairs by difference
+    pnPairCounters = ALLOC( int, 2 * nBitsMax );
+    memset( pnPairCounters, 0, sizeof(int) * 2 * nBitsMax );
+    // count the number of different pairs
+    for ( k = 0; k < nPairsTotal; k++ )
+        pnPairCounters[ pnLitsDiff[k] ]++;
+    // determine what pairs to take starting from the lower
+    // so that there would be exactly pPairsMax pairs
+    if ( pnPairCounters[0] != 0 )
+    {
+        printf( "The SOPs of the nodes are not cube-free. Run \"bdd; sop\" before \"fx\".\n" );
+        return 0;
+    }
+    if ( pnPairCounters[1] != 0 )
+    {
+        printf( "The SOPs of the nodes are not SCC-free. Run \"bdd; sop\" before \"fx\".\n" );
+        return 0;
+    }
+    assert( pnPairCounters[0] == 0 ); // otherwise, covers are not dup-free
+    assert( pnPairCounters[1] == 0 ); // otherwise, covers are not SCC-free
+    nSum = 0;
+    for ( k = 0; k < 2 * nBitsMax; k++ )
+    {
+        nSum += pnPairCounters[k];
+        if ( nSum >= nPairsMax )
+        {
+            CutOffNum   = k;
+            CutOffQuant = pnPairCounters[k] - (nSum - nPairsMax);
+            break;
+        }
+    }
+    FREE( pnPairCounters );
+
+    // set to 0 all the pairs above the cut-off number and quantity
+    iQuant = 0;
+    iPair  = 0;
+    for ( k = 0; k < nPairsTotal; k++ )
+        if ( pnLitsDiff[k] > CutOffNum ) 
+            pnLitsDiff[k] = 0;
+        else if ( pnLitsDiff[k] == CutOffNum )
+        {
+            if ( iQuant++ >= CutOffQuant )
+                pnLitsDiff[k] = 0;
+            else
+                iPair++;
+        }
+        else
+            iPair++;
+    assert( iPair == nPairsMax );
+
+    // collect the corresponding pairs and add the divisors
+    iPair = 0;
+    for ( c = 0; c < vCovers->nSize; c++ )
+        if ( pSopCover = vCovers->pArray[c] )
+        {
+            // get the var
+            pVar = p->ppVars[2*c+1];
+            // get the first cube
+            pCubeFirst = pVar->pFirst;
+            // get the last cube
+            pCubeLast = pCubeFirst;
+            for ( k = 0; k < pVar->nCubes; k++ )
+                pCubeLast = pCubeLast->pNext;
+            assert( pCubeLast == NULL || pCubeLast->pVar != pVar );
+
+            // go through the cube pairs
+            for ( pCube1 = pCubeFirst; pCube1 != pCubeLast; pCube1 = pCube1->pNext )
+                for ( pCube2 = pCube1->pNext; pCube2 != pCubeLast; pCube2 = pCube2->pNext )
+                    if ( pnLitsDiff[iPair++] )
+                    {   // create the divisors for this pair
+                        Fxu_MatrixAddDivisor( p, pCube1, pCube2 );
+                    }
+        }
+    assert( iPair == nPairsTotal );
+    FREE( pnLitsDiff );
+//PRT( "Preprocess", clock() - clk );
+    return 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the differences in each cube pair in the cover.]
+
+  Description [Takes the cover (pCover) and the array where the
+  diff counters go (pDiffs). The array pDiffs should have as many
+  entries as there are different pairs of cubes in the cover: n(n-1)/2.
+  Fills out the array pDiffs with the following info: For each cube
+  pair, included in the array is the number of literals in both cubes
+  after they are made cube free.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_CountPairDiffs( char * pCover, unsigned char pDiffs[] )
+{
+    char * pCube1, * pCube2;
+    int nOnes, nCubePairs, nFanins, v;
+    nCubePairs = 0;
+    nFanins = Abc_SopGetVarNum(pCover);
+    Abc_SopForEachCube( pCover, nFanins, pCube1 )
+    Abc_SopForEachCube( pCube1, nFanins, pCube2 )
+    {
+        if ( pCube1 == pCube2 )
+            continue;
+        nOnes = 0;
+        for ( v = 0; v < nFanins; v++ )
+            nOnes += (pCube1[v] != pCube2[v]);
+        pDiffs[nCubePairs++] = nOnes;
+    }
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuSelect.c b/src/opt/fxu/fxuSelect.c
new file mode 100644
index 00000000..b9265487
--- /dev/null
+++ b/src/opt/fxu/fxuSelect.c
@@ -0,0 +1,603 @@
+/**CFile****************************************************************
+
+  FileName    [fxuSelect.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Procedures to select the best divisor/complement pair.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuSelect.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define MAX_SIZE_LOOKAHEAD      20
+
+static int Fxu_MatrixFindComplement( Fxu_Matrix * p, int iVar );
+
+static Fxu_Double * Fxu_MatrixFindComplementSingle( Fxu_Matrix * p, Fxu_Single * pSingle );
+static Fxu_Single * Fxu_MatrixFindComplementDouble2( Fxu_Matrix * p, Fxu_Double * pDouble );
+static Fxu_Double * Fxu_MatrixFindComplementDouble4( Fxu_Matrix * p, Fxu_Double * pDouble );
+
+Fxu_Double * Fxu_MatrixFindDouble( Fxu_Matrix * p, 
+     int piVarsC1[], int piVarsC2[], int nVarsC1, int nVarsC2 );
+void Fxu_MatrixGetDoubleVars( Fxu_Matrix * p, Fxu_Double * pDouble, 
+    int piVarsC1[], int piVarsC2[], int * pnVarsC1, int * pnVarsC2 );
+
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Selects the best pair (Single,Double) and returns their weight.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_Select( Fxu_Matrix * p, Fxu_Single ** ppSingle, Fxu_Double ** ppDouble )
+{
+    // the top entries
+    Fxu_Single * pSingles[MAX_SIZE_LOOKAHEAD];
+    Fxu_Double * pDoubles[MAX_SIZE_LOOKAHEAD];
+    // the complements
+    Fxu_Double * pSCompl[MAX_SIZE_LOOKAHEAD];
+    Fxu_Single * pDComplS[MAX_SIZE_LOOKAHEAD];
+    Fxu_Double * pDComplD[MAX_SIZE_LOOKAHEAD];
+    Fxu_Pair * pPair;
+    int nSingles;
+    int nDoubles;
+    int i;
+    int WeightBest;
+    int WeightCur;
+    int iNum, fBestS;
+
+    // collect the top entries from the queues
+    for ( nSingles = 0; nSingles < MAX_SIZE_LOOKAHEAD; nSingles++ )
+    {
+        pSingles[nSingles] = Fxu_HeapSingleGetMax( p->pHeapSingle );
+        if ( pSingles[nSingles] == NULL )
+            break;
+    }
+    // put them back into the queue
+    for ( i = 0; i < nSingles; i++ )
+        if ( pSingles[i] )
+            Fxu_HeapSingleInsert( p->pHeapSingle, pSingles[i] );
+        
+    // the same for doubles
+    // collect the top entries from the queues
+    for ( nDoubles = 0; nDoubles < MAX_SIZE_LOOKAHEAD; nDoubles++ )
+    {
+        pDoubles[nDoubles] = Fxu_HeapDoubleGetMax( p->pHeapDouble );
+        if ( pDoubles[nDoubles] == NULL )
+            break;
+    }
+    // put them back into the queue
+    for ( i = 0; i < nDoubles; i++ )
+        if ( pDoubles[i] )
+            Fxu_HeapDoubleInsert( p->pHeapDouble, pDoubles[i] );
+
+    // for each single, find the complement double (if any)
+    for ( i = 0; i < nSingles; i++ )
+        if ( pSingles[i] )
+            pSCompl[i] = Fxu_MatrixFindComplementSingle( p, pSingles[i] );
+
+    // for each double, find the complement single or double (if any)
+    for ( i = 0; i < nDoubles; i++ )
+        if ( pDoubles[i] )
+        {
+            pPair = pDoubles[i]->lPairs.pHead;
+            if ( pPair->nLits1 == 1 && pPair->nLits2 == 1 )
+            {
+                pDComplS[i] = Fxu_MatrixFindComplementDouble2( p, pDoubles[i] );
+                pDComplD[i] = NULL;
+            }
+//            else if ( pPair->nLits1 == 2 && pPair->nLits2 == 2 )
+//            {
+//                pDComplS[i] = NULL;
+//                pDComplD[i] = Fxu_MatrixFindComplementDouble4( p, pDoubles[i] );
+//            }
+            else
+            {
+                pDComplS[i] = NULL;
+                pDComplD[i] = NULL;
+            }
+        }
+
+    // select the best pair
+    WeightBest = -1;
+    for ( i = 0; i < nSingles; i++ )
+    {
+        WeightCur = pSingles[i]->Weight;
+        if ( pSCompl[i] )
+        {
+            // add the weight of the double
+            WeightCur += pSCompl[i]->Weight;
+            // there is no need to implement this double, so...
+            pPair      = pSCompl[i]->lPairs.pHead;
+            WeightCur += pPair->nLits1 + pPair->nLits2;
+        }
+        if ( WeightBest < WeightCur )
+        {
+            WeightBest = WeightCur;
+            *ppSingle = pSingles[i];
+            *ppDouble = pSCompl[i];
+            fBestS = 1;
+            iNum = i;
+        }
+    }
+    for ( i = 0; i < nDoubles; i++ )
+    {
+        WeightCur = pDoubles[i]->Weight;
+        if ( pDComplS[i] )
+        {
+            // add the weight of the single
+            WeightCur += pDComplS[i]->Weight;
+            // there is no need to implement this double, so...
+            pPair      = pDoubles[i]->lPairs.pHead;
+            WeightCur += pPair->nLits1 + pPair->nLits2;
+        }
+        if ( WeightBest < WeightCur )
+        {
+            WeightBest = WeightCur;
+            *ppSingle = pDComplS[i];
+            *ppDouble = pDoubles[i];
+            fBestS = 0;
+            iNum = i;
+        }
+    }
+/*
+    // print the statistics
+    printf( "\n" );
+    for ( i = 0; i < nSingles; i++ )
+    {
+        printf( "Single #%d: Weight = %3d. ", i, pSingles[i]->Weight );
+        printf( "Compl: " );
+        if ( pSCompl[i] == NULL )
+            printf( "None." );
+        else
+            printf( "D  Weight = %3d  Sum = %3d", 
+                pSCompl[i]->Weight, pSCompl[i]->Weight + pSingles[i]->Weight );
+        printf( "\n" );
+    }
+    printf( "\n" );
+    for ( i = 0; i < nDoubles; i++ )
+    {
+        printf( "Double #%d: Weight = %3d. ", i, pDoubles[i]->Weight );
+        printf( "Compl: " );
+        if ( pDComplS[i] == NULL && pDComplD[i] == NULL )
+            printf( "None." );
+        else if ( pDComplS[i] )
+            printf( "S  Weight = %3d  Sum = %3d", 
+                pDComplS[i]->Weight, pDComplS[i]->Weight + pDoubles[i]->Weight );
+        else if ( pDComplD[i] )
+            printf( "D  Weight = %3d  Sum = %3d", 
+                pDComplD[i]->Weight, pDComplD[i]->Weight + pDoubles[i]->Weight );
+        printf( "\n" );
+    }
+    if ( WeightBest == -1 )
+        printf( "Selected NONE\n" );
+    else
+    {
+        printf( "Selected = %s.  ", fBestS? "S": "D" );
+        printf( "Number = %d.  ", iNum );
+        printf( "Weight = %d.\n", WeightBest );
+    }
+    printf( "\n" );
+*/
+    return WeightBest;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Double * Fxu_MatrixFindComplementSingle( Fxu_Matrix * p, Fxu_Single * pSingle )
+{
+//    int * pValue2Node = p->pValue2Node;
+    int iVar1,  iVar2;
+    int iVar1C, iVar2C;
+    // get the variables of this single div
+    iVar1  = pSingle->pVar1->iVar;
+    iVar2  = pSingle->pVar2->iVar;
+    iVar1C = Fxu_MatrixFindComplement( p, iVar1 );
+    iVar2C = Fxu_MatrixFindComplement( p, iVar2 );
+    if ( iVar1C == -1 || iVar2C == -1 )
+        return NULL;
+    assert( iVar1C < iVar2C );
+    return Fxu_MatrixFindDouble( p, &iVar1C, &iVar2C, 1, 1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Single * Fxu_MatrixFindComplementDouble2( Fxu_Matrix * p, Fxu_Double * pDouble )
+{
+//    int * pValue2Node = p->pValue2Node;
+    int piVarsC1[10], piVarsC2[10];
+    int nVarsC1, nVarsC2;
+    int iVar1,  iVar2, iVarTemp;
+    int iVar1C, iVar2C;
+    Fxu_Single * pSingle;
+
+    // get the variables of this double div
+    Fxu_MatrixGetDoubleVars( p, pDouble, piVarsC1, piVarsC2, &nVarsC1, &nVarsC2 );
+    assert( nVarsC1 == 1 );
+    assert( nVarsC2 == 1 );
+    iVar1 = piVarsC1[0];
+    iVar2 = piVarsC2[0];
+    assert( iVar1 < iVar2 );
+
+    iVar1C = Fxu_MatrixFindComplement( p, iVar1 );
+    iVar2C = Fxu_MatrixFindComplement( p, iVar2 );
+    if ( iVar1C == -1 || iVar2C == -1 )
+        return NULL;
+ 
+    // go through the queque and find this one
+//    assert( iVar1C < iVar2C );
+    if ( iVar1C > iVar2C )
+    {
+        iVarTemp = iVar1C;
+        iVar1C = iVar2C;
+        iVar2C = iVarTemp;
+    }
+
+    Fxu_MatrixForEachSingle( p, pSingle )
+        if ( pSingle->pVar1->iVar == iVar1C && pSingle->pVar2->iVar == iVar2C )
+            return pSingle;
+    return NULL;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Double * Fxu_MatrixFindComplementDouble4( Fxu_Matrix * p, Fxu_Double * pDouble )
+{
+//    int * pValue2Node = p->pValue2Node;
+    int piVarsC1[10], piVarsC2[10];
+    int nVarsC1, nVarsC2;
+    int iVar11,  iVar12,  iVar21,  iVar22;
+    int iVar11C, iVar12C, iVar21C, iVar22C;
+    int RetValue;
+
+    // get the variables of this double div
+    Fxu_MatrixGetDoubleVars( p, pDouble, piVarsC1, piVarsC2, &nVarsC1, &nVarsC2 );
+    assert( nVarsC1 == 2 && nVarsC2 == 2 );
+
+    iVar11 = piVarsC1[0];
+    iVar12 = piVarsC1[1];
+    iVar21 = piVarsC2[0];
+    iVar22 = piVarsC2[1];
+    assert( iVar11 < iVar21 );
+
+    iVar11C = Fxu_MatrixFindComplement( p, iVar11 );
+    iVar12C = Fxu_MatrixFindComplement( p, iVar12 );
+    iVar21C = Fxu_MatrixFindComplement( p, iVar21 );
+    iVar22C = Fxu_MatrixFindComplement( p, iVar22 );
+    if ( iVar11C == -1 || iVar12C == -1 || iVar21C == -1 || iVar22C == -1 )
+        return NULL;
+    if ( iVar11C != iVar21 || iVar12C != iVar22 || 
+         iVar21C != iVar11 || iVar22C != iVar12 )
+         return NULL;
+
+    // a'b' + ab   =>  a'b  + ab'
+    // a'b  + ab'  =>  a'b' + ab
+    // swap the second pair in each cube
+    RetValue    = piVarsC1[1];
+    piVarsC1[1] = piVarsC2[1];
+    piVarsC2[1] = RetValue;
+
+    return Fxu_MatrixFindDouble( p, piVarsC1, piVarsC2, 2, 2 );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_MatrixFindComplement( Fxu_Matrix * p, int iVar )
+{
+    return iVar ^ 1;
+/*
+//    int * pValue2Node = p->pValue2Node;
+    int iVarC;
+    int iNode;
+    int Beg, End;
+
+    // get the nodes
+    iNode = pValue2Node[iVar];
+    // get the first node with the same var
+    for ( Beg = iVar; Beg >= 0; Beg-- )
+        if ( pValue2Node[Beg] != iNode )
+        {
+            Beg++;
+            break;
+        }
+    // get the last node with the same var
+    for ( End = iVar;          ; End++ )
+        if ( pValue2Node[End] != iNode )
+        {
+            End--;
+            break;
+        }
+
+    // if one of the vars is not binary, quit
+    if ( End - Beg > 1 )
+        return -1;
+
+    // get the complements
+    if ( iVar == Beg )
+        iVarC = End;
+    else if ( iVar == End ) 
+        iVarC = Beg;
+    else
+    {
+        assert( 0 );
+    }
+    return iVarC;
+*/
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixGetDoubleVars( Fxu_Matrix * p, Fxu_Double * pDouble, 
+    int piVarsC1[], int piVarsC2[], int * pnVarsC1, int * pnVarsC2 )
+{
+    Fxu_Pair * pPair;
+    Fxu_Lit * pLit1, * pLit2;
+    int nLits1, nLits2;
+
+    // get the first pair
+    pPair = pDouble->lPairs.pHead;
+    // init the parameters
+    nLits1 = 0;
+    nLits2 = 0;
+    pLit1 = pPair->pCube1->lLits.pHead;
+    pLit2 = pPair->pCube2->lLits.pHead;
+    while ( 1 )
+    {
+        if ( pLit1 && pLit2 )
+        {
+            if ( pLit1->iVar == pLit2->iVar )
+            { // ensure cube-free
+                pLit1 = pLit1->pHNext;
+                pLit2 = pLit2->pHNext;
+            }
+            else if ( pLit1->iVar < pLit2->iVar )
+            {
+                piVarsC1[nLits1++] = pLit1->iVar;
+                 pLit1 = pLit1->pHNext;
+           }
+            else
+            {
+                piVarsC2[nLits2++] = pLit2->iVar;
+                pLit2 = pLit2->pHNext;
+            }
+        }
+        else if ( pLit1 && !pLit2 )
+        {
+            piVarsC1[nLits1++] = pLit1->iVar;
+            pLit1 = pLit1->pHNext;
+        }
+        else if ( !pLit1 && pLit2 )
+        {
+            piVarsC2[nLits2++] = pLit2->iVar;
+            pLit2 = pLit2->pHNext;
+        }
+        else
+            break;
+    }
+    *pnVarsC1 = nLits1;
+    *pnVarsC2 = nLits2;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Fxu_Double * Fxu_MatrixFindDouble( Fxu_Matrix * p, 
+     int piVarsC1[], int piVarsC2[], int nVarsC1, int nVarsC2 )
+{
+    int piVarsC1_[100], piVarsC2_[100];
+    int nVarsC1_, nVarsC2_, i;
+    Fxu_Double * pDouble;
+    Fxu_Pair * pPair;
+    unsigned Key;
+
+    assert( nVarsC1 > 0 );
+    assert( nVarsC2 > 0 );
+    assert( piVarsC1[0] < piVarsC2[0] );
+
+    // get the hash key
+    Key = Fxu_PairHashKeyArray( p, piVarsC1, piVarsC2, nVarsC1, nVarsC2 );
+    
+    // check if the divisor for this pair already exists
+    Key %= p->nTableSize;
+    Fxu_TableForEachDouble( p, Key, pDouble )
+    {
+        pPair = pDouble->lPairs.pHead;
+        if ( pPair->nLits1 != nVarsC1 )
+            continue;
+        if ( pPair->nLits2 != nVarsC2 )
+            continue;
+        // get the cubes of this divisor
+        Fxu_MatrixGetDoubleVars( p, pDouble, piVarsC1_, piVarsC2_, &nVarsC1_, &nVarsC2_ );
+        // compare lits of the first cube
+        for ( i = 0; i < nVarsC1; i++ )
+            if ( piVarsC1[i] != piVarsC1_[i] )
+                break;
+        if ( i != nVarsC1 )
+            continue;
+        // compare lits of the second cube
+        for ( i = 0; i < nVarsC2; i++ )
+            if ( piVarsC2[i] != piVarsC2_[i] )
+                break;
+        if ( i != nVarsC2 )
+            continue;
+        return pDouble;
+    }
+    return NULL;
+}
+
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_SelectSCD( Fxu_Matrix * p, int WeightLimit, Fxu_Var ** ppVar1, Fxu_Var ** ppVar2 )
+{
+//    int * pValue2Node = p->pValue2Node;
+    Fxu_Var * pVar1;
+    Fxu_Var * pVar2, * pVarTemp;
+    Fxu_Lit * pLitV, * pLitH;
+    int Coin;
+    int CounterAll;
+    int CounterTest;
+    int WeightCur;
+    int WeightBest;
+
+    CounterAll = 0;
+    CounterTest = 0;
+
+    WeightBest = -10;
+    
+    // iterate through the columns in the matrix
+    Fxu_MatrixForEachVariable( p, pVar1 )
+    {
+        // start collecting the affected vars
+        Fxu_MatrixRingVarsStart( p );
+
+        // go through all the literals of this variable
+        for ( pLitV = pVar1->lLits.pHead; pLitV; pLitV = pLitV->pVNext )
+        {
+            // for this literal, go through all the horizontal literals
+            for ( pLitH = pLitV->pHNext; pLitH; pLitH = pLitH->pHNext )
+            {
+                // get another variable
+                pVar2 = pLitH->pVar;
+                CounterAll++;
+                // skip the var if it is already used
+                if ( pVar2->pOrder )
+                    continue;
+                // skip the var if it belongs to the same node
+//                if ( pValue2Node[pVar1->iVar] == pValue2Node[pVar2->iVar] )
+//                    continue;
+                // collect the var
+                Fxu_MatrixRingVarsAdd( p, pVar2 );
+            }
+        }
+        // stop collecting the selected vars
+        Fxu_MatrixRingVarsStop( p );
+
+        // iterate through the selected vars
+        Fxu_MatrixForEachVarInRing( p, pVar2 )
+        {
+            CounterTest++;
+
+            // count the coincidence
+            Coin = Fxu_SingleCountCoincidence( p, pVar1, pVar2 );
+            assert( Coin > 0 );
+
+            // get the new weight
+            WeightCur = Coin - 2;
+
+            // compare the weights
+            if ( WeightBest < WeightCur )
+            {
+                WeightBest = WeightCur;
+                *ppVar1 = pVar1;
+                *ppVar2 = pVar2;
+            }
+        }
+        // unmark the vars
+        Fxu_MatrixForEachVarInRingSafe( p, pVar2, pVarTemp )
+            pVar2->pOrder = NULL;
+        Fxu_MatrixRingVarsReset( p );
+    }
+
+//    if ( WeightBest == WeightLimit )
+//        return -1;
+    return WeightBest;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuSingle.c b/src/opt/fxu/fxuSingle.c
new file mode 100644
index 00000000..73d9a76c
--- /dev/null
+++ b/src/opt/fxu/fxuSingle.c
@@ -0,0 +1,284 @@
+/**CFile****************************************************************
+
+  FileName    [fxuSingle.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Procedures to compute the set of single-cube divisors.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuSingle.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+#include "vec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Fxu_MatrixComputeSinglesOneCollect( Fxu_Matrix * p, Fxu_Var * pVar, Vec_Ptr_t * vSingles );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes and adds all single-cube divisors to storage.]
+
+  Description [This procedure should be called once when the matrix is
+  already contructed before the process of logic extraction begins..]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixComputeSingles( Fxu_Matrix * p, int fUse0, int nSingleMax )
+{
+    Fxu_Var * pVar;
+    Vec_Ptr_t * vSingles;
+    int i, k;
+    // set the weight limit
+    p->nWeightLimit = 1 - fUse0;
+    // iterate through columns in the matrix and collect single-cube divisors
+    vSingles = Vec_PtrAlloc( 10000 );
+    Fxu_MatrixForEachVariable( p, pVar )
+        Fxu_MatrixComputeSinglesOneCollect( p, pVar, vSingles );
+    p->nSingleTotal = Vec_PtrSize(vSingles) / 3;
+    // check if divisors should be filtered
+    if ( Vec_PtrSize(vSingles) > nSingleMax )
+    {
+        int * pWeigtCounts, nDivCount, Weight, i, c;;
+        assert( Vec_PtrSize(vSingles) % 3 == 0 );
+        // count how many divisors have the given weight
+        pWeigtCounts = ALLOC( int, 1000 );
+        memset( pWeigtCounts, 0, sizeof(int) * 1000 );
+        for ( i = 2; i < Vec_PtrSize(vSingles); i += 3 )
+        {
+            Weight = (int)Vec_PtrEntry(vSingles, i);
+            if ( Weight >= 999 )
+                pWeigtCounts[999]++;
+            else
+                pWeigtCounts[Weight]++;
+        }
+        // select the bound on the weight (above this bound, singles will be included)
+        nDivCount = 0;
+        for ( c = 999; c >= 0; c-- )
+        {
+            nDivCount += pWeigtCounts[c];
+            if ( nDivCount >= nSingleMax )
+                break;
+        }
+        free( pWeigtCounts );
+        // collect singles with the given costs
+        k = 0;
+        for ( i = 2; i < Vec_PtrSize(vSingles); i += 3 )
+        {
+            Weight = (int)Vec_PtrEntry(vSingles, i);
+            if ( Weight < c )
+                continue;
+            Vec_PtrWriteEntry( vSingles, k++, Vec_PtrEntry(vSingles, i-2) );
+            Vec_PtrWriteEntry( vSingles, k++, Vec_PtrEntry(vSingles, i-1) );
+            Vec_PtrWriteEntry( vSingles, k++, Vec_PtrEntry(vSingles, i) );
+            if ( k/3 == nSingleMax )
+                break;
+        }
+        Vec_PtrShrink( vSingles, k );
+        // adjust the weight limit
+        p->nWeightLimit = c;
+    }
+    // collect the selected divisors
+    assert( Vec_PtrSize(vSingles) % 3 == 0 );
+    for ( i = 0; i < Vec_PtrSize(vSingles); i += 3 )
+    {
+        Fxu_MatrixAddSingle( p, 
+            Vec_PtrEntry(vSingles,i), 
+            Vec_PtrEntry(vSingles,i+1), 
+            (int)Vec_PtrEntry(vSingles,i+2) );
+    }
+    Vec_PtrFree( vSingles );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the single-cube divisors associated with a new column.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixComputeSinglesOneCollect( Fxu_Matrix * p, Fxu_Var * pVar, Vec_Ptr_t * vSingles )
+{
+    Fxu_Lit * pLitV, * pLitH;
+    Fxu_Var * pVar2;
+    int Coin;
+    int WeightCur;
+
+    // start collecting the affected vars
+    Fxu_MatrixRingVarsStart( p );
+    // go through all the literals of this variable
+    for ( pLitV = pVar->lLits.pHead; pLitV; pLitV = pLitV->pVNext )
+        // for this literal, go through all the horizontal literals
+        for ( pLitH = pLitV->pHPrev; pLitH; pLitH = pLitH->pHPrev )
+        {
+            // get another variable
+            pVar2 = pLitH->pVar;
+            // skip the var if it is already used
+            if ( pVar2->pOrder )
+                continue;
+            // skip the var if it belongs to the same node
+//            if ( pValue2Node[pVar->iVar] == pValue2Node[pVar2->iVar] )
+//                continue;
+            // collect the var
+            Fxu_MatrixRingVarsAdd( p, pVar2 );
+        }
+    // stop collecting the selected vars
+    Fxu_MatrixRingVarsStop( p );
+
+    // iterate through the selected vars
+    Fxu_MatrixForEachVarInRing( p, pVar2 )
+    {
+        // count the coincidence
+        Coin = Fxu_SingleCountCoincidence( p, pVar2, pVar );
+        assert( Coin > 0 );
+        // get the new weight
+        WeightCur = Coin - 2;
+        // peformance fix (August 24, 2007)
+        if ( WeightCur >= p->nWeightLimit )
+        {
+            Vec_PtrPush( vSingles, pVar2 );
+            Vec_PtrPush( vSingles, pVar );
+            Vec_PtrPush( vSingles, (void *)WeightCur );
+        }
+    }
+
+    // unmark the vars
+    Fxu_MatrixRingVarsUnmark( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the single-cube divisors associated with a new column.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_MatrixComputeSinglesOne( Fxu_Matrix * p, Fxu_Var * pVar )
+{
+    Fxu_Lit * pLitV, * pLitH;
+    Fxu_Var * pVar2;
+    int Coin;
+    int WeightCur;
+
+    // start collecting the affected vars
+    Fxu_MatrixRingVarsStart( p );
+    // go through all the literals of this variable
+    for ( pLitV = pVar->lLits.pHead; pLitV; pLitV = pLitV->pVNext )
+        // for this literal, go through all the horizontal literals
+        for ( pLitH = pLitV->pHPrev; pLitH; pLitH = pLitH->pHPrev )
+        {
+            // get another variable
+            pVar2 = pLitH->pVar;
+            // skip the var if it is already used
+            if ( pVar2->pOrder )
+                continue;
+            // skip the var if it belongs to the same node
+//            if ( pValue2Node[pVar->iVar] == pValue2Node[pVar2->iVar] )
+//                continue;
+            // collect the var
+            Fxu_MatrixRingVarsAdd( p, pVar2 );
+        }
+    // stop collecting the selected vars
+    Fxu_MatrixRingVarsStop( p );
+
+    // iterate through the selected vars
+    Fxu_MatrixForEachVarInRing( p, pVar2 )
+    {
+        // count the coincidence
+        Coin = Fxu_SingleCountCoincidence( p, pVar2, pVar );
+        assert( Coin > 0 );
+        // get the new weight
+        WeightCur = Coin - 2;
+        // peformance fix (August 24, 2007)
+//        if ( WeightCur >= 0 )
+//        Fxu_MatrixAddSingle( p, pVar2, pVar, WeightCur );
+        if ( WeightCur >= p->nWeightLimit )
+            Fxu_MatrixAddSingle( p, pVar2, pVar, WeightCur );
+    }
+    // unmark the vars
+    Fxu_MatrixRingVarsUnmark( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the coincidence count of two columns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_SingleCountCoincidence( Fxu_Matrix * p, Fxu_Var * pVar1, Fxu_Var * pVar2 )
+{
+    Fxu_Lit * pLit1, * pLit2;
+    int Result;
+
+    // compute the coincidence count
+    Result = 0;
+    pLit1  = pVar1->lLits.pHead;
+    pLit2  = pVar2->lLits.pHead;
+    while ( 1 )
+    {
+        if ( pLit1 && pLit2 )
+        {
+            if ( pLit1->pCube->pVar->iVar == pLit2->pCube->pVar->iVar )
+            { // the variables are the same
+                if ( pLit1->iCube == pLit2->iCube )
+                { // the literals are the same
+                    pLit1 = pLit1->pVNext;
+                    pLit2 = pLit2->pVNext;
+                    // add this literal to the coincidence
+                    Result++;
+                }
+                else if ( pLit1->iCube < pLit2->iCube )
+                    pLit1 = pLit1->pVNext;
+                else
+                    pLit2 = pLit2->pVNext;
+            }
+            else if ( pLit1->pCube->pVar->iVar < pLit2->pCube->pVar->iVar )
+                pLit1 = pLit1->pVNext;
+            else
+                pLit2 = pLit2->pVNext;
+        }
+        else if ( pLit1 && !pLit2 )
+            pLit1 = pLit1->pVNext;
+        else if ( !pLit1 && pLit2 )
+            pLit2 = pLit2->pVNext;
+        else
+            break;
+    }
+    return Result;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/fxuUpdate.c b/src/opt/fxu/fxuUpdate.c
new file mode 100644
index 00000000..274f79f6
--- /dev/null
+++ b/src/opt/fxu/fxuUpdate.c
@@ -0,0 +1,806 @@
+/**CFile****************************************************************
+
+  FileName    [fxuUpdate.c]
+
+  PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
+
+  Synopsis    [Updating the sparse matrix when divisors are accepted.]
+
+  Author      [MVSIS Group]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - February 1, 2003.]
+
+  Revision    [$Id: fxuUpdate.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fxuInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Fxu_UpdateDoublePairs( Fxu_Matrix * p, Fxu_Double * pDouble, Fxu_Var * pVar );
+static void Fxu_UpdateMatrixDoubleCreateCubes( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2, Fxu_Double * pDiv );
+static void Fxu_UpdateMatrixDoubleClean( Fxu_Matrix * p, Fxu_Cube * pCubeUse, Fxu_Cube * pCubeRem );
+static void Fxu_UpdateMatrixSingleClean( Fxu_Matrix * p, Fxu_Var * pVar1, Fxu_Var * pVar2, Fxu_Var * pVarNew );
+
+static void Fxu_UpdateCreateNewVars( Fxu_Matrix * p, Fxu_Var ** ppVarC, Fxu_Var ** ppVarD, int nCubes );
+static int  Fxu_UpdatePairCompare( Fxu_Pair ** ppP1, Fxu_Pair ** ppP2 );
+static void Fxu_UpdatePairsSort( Fxu_Matrix * p, Fxu_Double * pDouble );
+
+static void Fxu_UpdateCleanOldDoubles( Fxu_Matrix * p, Fxu_Double * pDiv, Fxu_Cube * pCube );
+static void Fxu_UpdateAddNewDoubles( Fxu_Matrix * p, Fxu_Cube * pCube );
+static void Fxu_UpdateCleanOldSingles( Fxu_Matrix * p );
+static void Fxu_UpdateAddNewSingles( Fxu_Matrix * p, Fxu_Var * pVar );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the matrix after selecting two divisors.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_Update( Fxu_Matrix * p, Fxu_Single * pSingle, Fxu_Double * pDouble )
+{
+    Fxu_Cube * pCube, * pCubeNew;
+    Fxu_Var * pVarC, * pVarD;
+    Fxu_Var * pVar1, * pVar2;
+
+    // consider trivial cases
+    if ( pSingle == NULL )
+    {
+        assert( pDouble->Weight == Fxu_HeapDoubleReadMaxWeight( p->pHeapDouble ) );
+        Fxu_UpdateDouble( p );
+        return;
+    }
+    if ( pDouble == NULL )
+    {
+        assert( pSingle->Weight == Fxu_HeapSingleReadMaxWeight( p->pHeapSingle ) );
+        Fxu_UpdateSingle( p );
+        return;
+    }
+
+    // get the variables of the single
+    pVar1 = pSingle->pVar1;
+    pVar2 = pSingle->pVar2;
+
+    // remove the best double from the heap
+    Fxu_HeapDoubleDelete( p->pHeapDouble, pDouble );
+    // remove the best divisor from the table
+    Fxu_ListTableDelDivisor( p, pDouble );
+
+    // create two new columns (vars)
+    Fxu_UpdateCreateNewVars( p, &pVarC, &pVarD, 1 );
+    // create one new row (cube)
+    pCubeNew = Fxu_MatrixAddCube( p, pVarD, 0 );
+    pCubeNew->pFirst = pCubeNew;
+    // set the first cube of the positive var
+    pVarD->pFirst = pCubeNew;
+
+    // start collecting the affected vars and cubes
+    Fxu_MatrixRingCubesStart( p );
+    Fxu_MatrixRingVarsStart( p );
+    // add the vars
+    Fxu_MatrixRingVarsAdd( p, pVar1 );
+    Fxu_MatrixRingVarsAdd( p, pVar2 );
+    // remove the literals and collect the affected cubes
+    // remove the divisors associated with this cube
+       // add to the affected cube the literal corresponding to the new column
+    Fxu_UpdateMatrixSingleClean( p, pVar1, pVar2, pVarD );
+    // replace each two cubes of the pair by one new cube
+    // the new cube contains the base and the new literal
+    Fxu_UpdateDoublePairs( p, pDouble, pVarC );
+    // stop collecting the affected vars and cubes
+    Fxu_MatrixRingCubesStop( p );
+    Fxu_MatrixRingVarsStop( p );
+
+    // add the literals to the new cube
+    assert( pVar1->iVar < pVar2->iVar );
+    assert( Fxu_SingleCountCoincidence( p, pVar1, pVar2 ) == 0 );
+    Fxu_MatrixAddLiteral( p, pCubeNew, pVar1 );
+    Fxu_MatrixAddLiteral( p, pCubeNew, pVar2 );
+
+    // create new doubles; we cannot add them in the same loop
+    // because we first have to create *all* new cubes for each node
+    Fxu_MatrixForEachCubeInRing( p, pCube )
+           Fxu_UpdateAddNewDoubles( p, pCube );
+    // update the singles after removing some literals
+    Fxu_UpdateCleanOldSingles( p );
+
+    // undo the temporary rings with cubes and vars
+    Fxu_MatrixRingCubesUnmark( p );
+    Fxu_MatrixRingVarsUnmark( p );
+    // we should undo the rings before creating new singles
+
+    // create new singles
+    Fxu_UpdateAddNewSingles( p, pVarC );
+    Fxu_UpdateAddNewSingles( p, pVarD );
+
+    // recycle the divisor
+    MEM_FREE_FXU( p, Fxu_Double, 1, pDouble );
+    p->nDivs3++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates after accepting single cube divisor.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateSingle( Fxu_Matrix * p )
+{
+    Fxu_Single * pSingle;
+    Fxu_Cube * pCube, * pCubeNew;
+    Fxu_Var * pVarC, * pVarD;
+    Fxu_Var * pVar1, * pVar2;
+
+    // read the best divisor from the heap
+    pSingle = Fxu_HeapSingleReadMax( p->pHeapSingle );
+    // get the variables of this single-cube divisor
+    pVar1 = pSingle->pVar1;
+    pVar2 = pSingle->pVar2;
+
+    // create two new columns (vars)
+    Fxu_UpdateCreateNewVars( p, &pVarC, &pVarD, 1 );
+    // create one new row (cube)
+    pCubeNew = Fxu_MatrixAddCube( p, pVarD, 0 );
+    pCubeNew->pFirst = pCubeNew;
+    // set the first cube
+    pVarD->pFirst = pCubeNew;
+
+    // start collecting the affected vars and cubes
+    Fxu_MatrixRingCubesStart( p );
+    Fxu_MatrixRingVarsStart( p );
+    // add the vars
+    Fxu_MatrixRingVarsAdd( p, pVar1 );
+    Fxu_MatrixRingVarsAdd( p, pVar2 );
+    // remove the literals and collect the affected cubes
+    // remove the divisors associated with this cube
+       // add to the affected cube the literal corresponding to the new column
+    Fxu_UpdateMatrixSingleClean( p, pVar1, pVar2, pVarD );
+    // stop collecting the affected vars and cubes
+    Fxu_MatrixRingCubesStop( p );
+    Fxu_MatrixRingVarsStop( p );
+
+    // add the literals to the new cube
+    assert( pVar1->iVar < pVar2->iVar );
+    assert( Fxu_SingleCountCoincidence( p, pVar1, pVar2 ) == 0 );
+    Fxu_MatrixAddLiteral( p, pCubeNew, pVar1 );
+    Fxu_MatrixAddLiteral( p, pCubeNew, pVar2 );
+
+    // create new doubles; we cannot add them in the same loop
+    // because we first have to create *all* new cubes for each node
+    Fxu_MatrixForEachCubeInRing( p, pCube )
+           Fxu_UpdateAddNewDoubles( p, pCube );
+    // update the singles after removing some literals
+    Fxu_UpdateCleanOldSingles( p );
+    // we should undo the rings before creating new singles
+
+    // unmark the cubes
+    Fxu_MatrixRingCubesUnmark( p );
+    Fxu_MatrixRingVarsUnmark( p );
+
+    // create new singles
+    Fxu_UpdateAddNewSingles( p, pVarC );
+    Fxu_UpdateAddNewSingles( p, pVarD );
+    p->nDivs1++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the matrix after accepting a double cube divisor.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateDouble( Fxu_Matrix * p )
+{
+    Fxu_Double * pDiv;
+    Fxu_Cube * pCube, * pCubeNew1, * pCubeNew2;
+    Fxu_Var * pVarC, * pVarD;
+
+    // remove the best divisor from the heap
+    pDiv = Fxu_HeapDoubleGetMax( p->pHeapDouble );
+    // remove the best divisor from the table
+    Fxu_ListTableDelDivisor( p, pDiv );
+
+    // create two new columns (vars)
+    Fxu_UpdateCreateNewVars( p, &pVarC, &pVarD, 2 );
+    // create two new rows (cubes)
+    pCubeNew1 = Fxu_MatrixAddCube( p, pVarD, 0 );
+    pCubeNew1->pFirst = pCubeNew1;
+    pCubeNew2 = Fxu_MatrixAddCube( p, pVarD, 1 );
+    pCubeNew2->pFirst = pCubeNew1;
+    // set the first cube
+    pVarD->pFirst = pCubeNew1;
+
+    // add the literals to the new cubes
+    Fxu_UpdateMatrixDoubleCreateCubes( p, pCubeNew1, pCubeNew2, pDiv );
+
+    // start collecting the affected cubes and vars
+    Fxu_MatrixRingCubesStart( p );
+    Fxu_MatrixRingVarsStart( p );
+    // replace each two cubes of the pair by one new cube
+    // the new cube contains the base and the new literal
+    Fxu_UpdateDoublePairs( p, pDiv, pVarD );
+    // stop collecting the affected cubes and vars
+    Fxu_MatrixRingCubesStop( p );
+    Fxu_MatrixRingVarsStop( p );
+    
+    // create new doubles; we cannot add them in the same loop
+    // because we first have to create *all* new cubes for each node
+    Fxu_MatrixForEachCubeInRing( p, pCube )
+           Fxu_UpdateAddNewDoubles( p, pCube );
+    // update the singles after removing some literals
+    Fxu_UpdateCleanOldSingles( p );
+
+    // undo the temporary rings with cubes and vars
+    Fxu_MatrixRingCubesUnmark( p );
+    Fxu_MatrixRingVarsUnmark( p );
+    // we should undo the rings before creating new singles
+
+    // create new singles
+    Fxu_UpdateAddNewSingles( p, pVarC );
+    Fxu_UpdateAddNewSingles( p, pVarD );
+
+    // recycle the divisor
+    MEM_FREE_FXU( p, Fxu_Double, 1, pDiv );
+    p->nDivs2++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Update the pairs.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateDoublePairs( Fxu_Matrix * p, Fxu_Double * pDouble, Fxu_Var * pVar )
+{
+    Fxu_Pair * pPair;
+    Fxu_Cube * pCubeUse, * pCubeRem;
+    int i;
+
+    // collect and sort the pairs
+    Fxu_UpdatePairsSort( p, pDouble );
+//    for ( i = 0; i < p->nPairsTemp; i++ )
+    for ( i = 0; i < p->vPairs->nSize; i++ )
+    {
+        // get the pair
+//        pPair = p->pPairsTemp[i];
+        pPair = p->vPairs->pArray[i];
+        // out of the two cubes, select the one which comes earlier
+        pCubeUse = Fxu_PairMinCube( pPair );
+        pCubeRem = Fxu_PairMaxCube( pPair );
+        // collect the affected cube
+        assert( pCubeUse->pOrder == NULL );
+        Fxu_MatrixRingCubesAdd( p, pCubeUse );
+
+        // remove some literals from pCubeUse and all literals from pCubeRem
+        Fxu_UpdateMatrixDoubleClean( p, pCubeUse, pCubeRem );
+        // add a literal that depends on the new variable
+        Fxu_MatrixAddLiteral( p, pCubeUse, pVar );    
+        // check the literal count
+        assert( pCubeUse->lLits.nItems == pPair->nBase + 1 );
+        assert( pCubeRem->lLits.nItems == 0 );
+
+        // update the divisors by removing useless pairs
+        Fxu_UpdateCleanOldDoubles( p, pDouble, pCubeUse );
+        Fxu_UpdateCleanOldDoubles( p, pDouble, pCubeRem );
+        // remove the pair
+        MEM_FREE_FXU( p, Fxu_Pair, 1, pPair );
+    }
+    p->vPairs->nSize = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Add two cubes corresponding to the given double-cube divisor.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateMatrixDoubleCreateCubes( Fxu_Matrix * p, Fxu_Cube * pCube1, Fxu_Cube * pCube2, Fxu_Double * pDiv )
+{
+    Fxu_Lit * pLit1, * pLit2;
+    Fxu_Pair * pPair;
+    int nBase, nLits1, nLits2;
+
+    // fill in the SOP and copy the fanins
+    nBase = nLits1 = nLits2 = 0;
+    pPair = pDiv->lPairs.pHead;
+    pLit1 = pPair->pCube1->lLits.pHead;
+    pLit2 = pPair->pCube2->lLits.pHead;
+    while ( 1 )
+    {
+        if ( pLit1 && pLit2 )
+        {
+            if ( pLit1->iVar == pLit2->iVar )
+            { // skip the cube free part
+                pLit1 = pLit1->pHNext;
+                pLit2 = pLit2->pHNext;
+                nBase++;
+            }
+            else if ( pLit1->iVar < pLit2->iVar )
+            {    // add literal to the first cube
+                Fxu_MatrixAddLiteral( p, pCube1, pLit1->pVar );
+                // move to the next literal in this cube
+                pLit1 = pLit1->pHNext;
+                nLits1++;
+            }
+            else
+            {    // add literal to the second cube
+                Fxu_MatrixAddLiteral( p, pCube2, pLit2->pVar );
+                // move to the next literal in this cube
+                pLit2 = pLit2->pHNext;
+                nLits2++;
+            }
+        }
+        else if ( pLit1 && !pLit2 )
+        {    // add literal to the first cube
+            Fxu_MatrixAddLiteral( p, pCube1, pLit1->pVar );
+            // move to the next literal in this cube
+            pLit1 = pLit1->pHNext;
+            nLits1++;
+        }
+        else if ( !pLit1 && pLit2 )
+        {    // add literal to the second cube
+            Fxu_MatrixAddLiteral( p, pCube2, pLit2->pVar );
+            // move to the next literal in this cube
+            pLit2 = pLit2->pHNext;
+            nLits2++;
+        }
+        else
+            break;
+    }
+    assert( pPair->nLits1 == nLits1 );
+    assert( pPair->nLits2 == nLits2 );
+    assert( pPair->nBase == nBase );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Create the node equal to double-cube divisor.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateMatrixDoubleClean( Fxu_Matrix * p, Fxu_Cube * pCubeUse, Fxu_Cube * pCubeRem )
+{
+    Fxu_Lit * pLit1, * bLit1Next;
+    Fxu_Lit * pLit2, * bLit2Next;
+
+    // initialize the starting literals
+    pLit1     = pCubeUse->lLits.pHead;
+    pLit2     = pCubeRem->lLits.pHead;
+    bLit1Next = pLit1? pLit1->pHNext: NULL;
+    bLit2Next = pLit2? pLit2->pHNext: NULL;
+    // go through the pair and remove the literals in the base
+    // from the first cube and all literals from the second cube
+    while ( 1 )
+    {
+        if ( pLit1 && pLit2 )
+        {
+            if ( pLit1->iVar == pLit2->iVar )
+            {  // this literal is present in both cubes - it belongs to the base
+                // mark the affected var
+                if ( pLit1->pVar->pOrder == NULL )
+                    Fxu_MatrixRingVarsAdd( p, pLit1->pVar );
+                // leave the base in pCubeUse; delete it from pCubeRem
+                Fxu_MatrixDelLiteral( p, pLit2 );
+                // step to the next literals
+                pLit1     = bLit1Next;
+                pLit2     = bLit2Next;
+                bLit1Next = pLit1? pLit1->pHNext: NULL;
+                bLit2Next = pLit2? pLit2->pHNext: NULL;
+            }
+            else if ( pLit1->iVar < pLit2->iVar )
+            { // this literal is present in pCubeUse - remove it
+                // mark the affected var
+                if ( pLit1->pVar->pOrder == NULL )
+                    Fxu_MatrixRingVarsAdd( p, pLit1->pVar );
+                // delete this literal
+                Fxu_MatrixDelLiteral( p, pLit1 );
+                // step to the next literals
+                pLit1     = bLit1Next;
+                bLit1Next = pLit1? pLit1->pHNext: NULL;
+            }
+            else
+            { // this literal is present in pCubeRem - remove it
+                // mark the affected var
+                if ( pLit2->pVar->pOrder == NULL )
+                    Fxu_MatrixRingVarsAdd( p, pLit2->pVar );
+                // delete this literal
+                Fxu_MatrixDelLiteral( p, pLit2 );
+                // step to the next literals
+                pLit2     = bLit2Next;
+                bLit2Next = pLit2? pLit2->pHNext: NULL;
+            }
+        }
+        else if ( pLit1 && !pLit2 )
+        { // this literal is present in pCubeUse - leave it
+            // mark the affected var
+            if ( pLit1->pVar->pOrder == NULL )
+                Fxu_MatrixRingVarsAdd( p, pLit1->pVar );
+            // delete this literal
+            Fxu_MatrixDelLiteral( p, pLit1 );
+            // step to the next literals
+            pLit1     = bLit1Next;
+            bLit1Next = pLit1? pLit1->pHNext: NULL;
+        }
+        else if ( !pLit1 && pLit2 )
+        { // this literal is present in pCubeRem - remove it
+            // mark the affected var
+            if ( pLit2->pVar->pOrder == NULL )
+                Fxu_MatrixRingVarsAdd( p, pLit2->pVar );
+            // delete this literal
+            Fxu_MatrixDelLiteral( p, pLit2 );
+            // step to the next literals
+            pLit2     = bLit2Next;
+            bLit2Next = pLit2? pLit2->pHNext: NULL;
+        }
+        else
+            break;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the matrix after selecting a single cube divisor.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateMatrixSingleClean( Fxu_Matrix * p, Fxu_Var * pVar1, Fxu_Var * pVar2, Fxu_Var * pVarNew )
+{
+    Fxu_Lit * pLit1, * bLit1Next;
+    Fxu_Lit * pLit2, * bLit2Next;
+
+    // initialize the starting literals
+    pLit1     = pVar1->lLits.pHead;
+    pLit2     = pVar2->lLits.pHead;
+    bLit1Next = pLit1? pLit1->pVNext: NULL;
+    bLit2Next = pLit2? pLit2->pVNext: NULL;
+    while ( 1 )
+    {
+        if ( pLit1 && pLit2 )
+        {
+            if ( pLit1->pCube->pVar->iVar == pLit2->pCube->pVar->iVar )
+            { // these literals coincide 
+                if ( pLit1->iCube == pLit2->iCube )
+                { // these literals coincide 
+                
+                    // collect the affected cube
+                    assert( pLit1->pCube->pOrder == NULL );
+                    Fxu_MatrixRingCubesAdd( p, pLit1->pCube );
+
+                    // add the literal to this cube corresponding to the new column
+                    Fxu_MatrixAddLiteral( p, pLit1->pCube, pVarNew );
+                    // clean the old cubes
+                    Fxu_UpdateCleanOldDoubles( p, NULL, pLit1->pCube );
+
+                    // remove the literals 
+                    Fxu_MatrixDelLiteral( p, pLit1 );
+                    Fxu_MatrixDelLiteral( p, pLit2 );
+
+                    // go to the next literals
+                    pLit1     = bLit1Next;
+                    pLit2     = bLit2Next;
+                    bLit1Next = pLit1? pLit1->pVNext: NULL;
+                    bLit2Next = pLit2? pLit2->pVNext: NULL;
+                }
+                else if ( pLit1->iCube < pLit2->iCube )
+                {
+                    pLit1     = bLit1Next;
+                    bLit1Next = pLit1? pLit1->pVNext: NULL;
+                }
+                else
+                {
+                    pLit2     = bLit2Next;
+                    bLit2Next = pLit2? pLit2->pVNext: NULL;
+                }
+            }
+            else if ( pLit1->pCube->pVar->iVar < pLit2->pCube->pVar->iVar )
+            {
+                pLit1     = bLit1Next;
+                bLit1Next = pLit1? pLit1->pVNext: NULL;
+            }
+            else
+            {
+                pLit2     = bLit2Next;
+                bLit2Next = pLit2? pLit2->pVNext: NULL;
+            }
+        }
+        else if ( pLit1 && !pLit2 )
+        {
+            pLit1     = bLit1Next;
+            bLit1Next = pLit1? pLit1->pVNext: NULL;
+        }
+        else if ( !pLit1 && pLit2 )
+        {
+            pLit2     = bLit2Next;
+            bLit2Next = pLit2? pLit2->pVNext: NULL;
+        }
+        else
+            break;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sort the pairs.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdatePairsSort( Fxu_Matrix * p, Fxu_Double * pDouble )
+{
+    Fxu_Pair * pPair;
+    // order the pairs by the first cube to ensure that new literals are added 
+    // to the matrix from top to bottom - collect pairs into the array
+    p->vPairs->nSize = 0;
+    Fxu_DoubleForEachPair( pDouble, pPair )
+        Vec_PtrPush( p->vPairs, pPair );
+    if ( p->vPairs->nSize < 2 )
+        return;
+    // sort
+    qsort( (void *)p->vPairs->pArray, p->vPairs->nSize, sizeof(Fxu_Pair *), 
+        (int (*)(const void *, const void *)) Fxu_UpdatePairCompare );
+    assert( Fxu_UpdatePairCompare( (Fxu_Pair**)p->vPairs->pArray, (Fxu_Pair**)p->vPairs->pArray + p->vPairs->nSize - 1 ) < 0 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compares the vars by their number.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fxu_UpdatePairCompare( Fxu_Pair ** ppP1, Fxu_Pair ** ppP2 )
+{
+    Fxu_Cube * pC1 = (*ppP1)->pCube1;
+    Fxu_Cube * pC2 = (*ppP2)->pCube1;
+    int iP1CubeMin, iP2CubeMin;
+    if ( pC1->pVar->iVar < pC2->pVar->iVar )
+        return -1;
+    if ( pC1->pVar->iVar > pC2->pVar->iVar )
+        return 1;
+    iP1CubeMin = Fxu_PairMinCubeInt( *ppP1 );
+    iP2CubeMin = Fxu_PairMinCubeInt( *ppP2 );
+    if ( iP1CubeMin < iP2CubeMin )
+        return -1;
+    if ( iP1CubeMin > iP2CubeMin )
+        return 1;
+    assert( 0 );
+    return 0;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Create new variables.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateCreateNewVars( Fxu_Matrix * p, Fxu_Var ** ppVarC, Fxu_Var ** ppVarD, int nCubes )
+{
+    Fxu_Var * pVarC, * pVarD;
+
+    // add a new column for the complement
+    pVarC = Fxu_MatrixAddVar( p );
+    pVarC->nCubes = 0;
+    // add a new column for the divisor
+    pVarD = Fxu_MatrixAddVar( p );
+    pVarD->nCubes = nCubes;
+
+    // mark this entry in the Value2Node array
+//    assert( p->pValue2Node[pVarC->iVar] > 0 );
+//    p->pValue2Node[pVarD->iVar  ] = p->pValue2Node[pVarC->iVar];
+//    p->pValue2Node[pVarD->iVar+1] = p->pValue2Node[pVarC->iVar]+1;
+
+    *ppVarC = pVarC;
+    *ppVarD = pVarD;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateCleanOldDoubles( Fxu_Matrix * p, Fxu_Double * pDiv, Fxu_Cube * pCube )
+{
+    Fxu_Double * pDivCur;
+    Fxu_Pair * pPair;
+    int i;
+
+    // if the cube is a recently introduced one
+    // it does not have pairs allocated
+    // in this case, there is nothing to update
+    if ( pCube->pVar->ppPairs == NULL )
+        return;
+
+    // go through all the pairs of this cube
+    Fxu_CubeForEachPair( pCube, pPair, i )
+    {
+         // get the divisor of this pair
+        pDivCur = pPair->pDiv;
+        // skip the current divisor
+        if ( pDivCur == pDiv )
+            continue;
+        // remove this pair
+        Fxu_ListDoubleDelPair( pDivCur, pPair );    
+        // the divisor may have become useless by now
+        if ( pDivCur->lPairs.nItems == 0 )
+        {
+            assert( pDivCur->Weight == pPair->nBase - 1 );
+              Fxu_HeapDoubleDelete( p->pHeapDouble, pDivCur );
+            Fxu_MatrixDelDivisor( p, pDivCur );
+        }
+        else
+        {
+            // update the divisor's weight
+            pDivCur->Weight -= pPair->nLits1 + pPair->nLits2 - 1 + pPair->nBase;
+              Fxu_HeapDoubleUpdate( p->pHeapDouble, pDivCur );
+        }
+        MEM_FREE_FXU( p, Fxu_Pair, 1, pPair );
+    }
+    // finally erase all the pair info associated with this cube
+    Fxu_PairClearStorage( pCube );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the new divisors that depend on the cube.]
+
+  Description [Go through all the non-empty cubes of this cover 
+  (except the given cube) and, for each of them, add the new divisor 
+  with the given cube.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateAddNewDoubles( Fxu_Matrix * p, Fxu_Cube * pCube )
+{
+    Fxu_Cube * pTemp;
+    assert( pCube->pOrder );
+
+    // if the cube is a recently introduced one
+    // it does not have pairs allocated
+    // in this case, there is nothing to update
+    if ( pCube->pVar->ppPairs == NULL )
+        return;
+
+    for ( pTemp = pCube->pFirst; pTemp->pVar == pCube->pVar; pTemp = pTemp->pNext )
+    {
+        // do not add pairs with the empty cubes
+        if ( pTemp->lLits.nItems == 0 )
+            continue;
+        // to prevent adding duplicated pairs of the new cubes
+        // do not add the pair, if the current cube is marked 
+        if ( pTemp->pOrder && pTemp >= pCube )
+            continue;
+        Fxu_MatrixAddDivisor( p, pTemp, pCube );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Removes old single cube divisors.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateCleanOldSingles( Fxu_Matrix * p )
+{ 
+    Fxu_Single * pSingle, * pSingle2;
+    int WeightNew;
+    int Counter = 0;
+
+    Fxu_MatrixForEachSingleSafe( p, pSingle, pSingle2 )
+    {
+        // if at least one of the variables is marked, recalculate
+        if ( pSingle->pVar1->pOrder || pSingle->pVar2->pOrder )
+        {
+            Counter++;
+            // get the new weight
+            WeightNew = -2 + Fxu_SingleCountCoincidence( p, pSingle->pVar1, pSingle->pVar2 );
+            if ( WeightNew >= 0 )
+            {
+                pSingle->Weight = WeightNew;
+                Fxu_HeapSingleUpdate( p->pHeapSingle, pSingle );
+            }
+            else
+            {
+                Fxu_HeapSingleDelete( p->pHeapSingle, pSingle );
+                Fxu_ListMatrixDelSingle( p, pSingle );
+                MEM_FREE_FXU( p, Fxu_Single, 1, pSingle );
+            }
+        }
+    }
+//    printf( "Called procedure %d times.\n", Counter );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the single cube divisors.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fxu_UpdateAddNewSingles( Fxu_Matrix * p, Fxu_Var * pVar )
+{
+    Fxu_MatrixComputeSinglesOne( p, pVar );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/fxu/module.make b/src/opt/fxu/module.make
new file mode 100644
index 00000000..dd8acd40
--- /dev/null
+++ b/src/opt/fxu/module.make
@@ -0,0 +1,12 @@
+SRC +=  src/opt/fxu/fxu.c \
+    src/opt/fxu/fxuCreate.c \
+    src/opt/fxu/fxuHeapD.c \
+    src/opt/fxu/fxuHeapS.c \
+    src/opt/fxu/fxuList.c \
+    src/opt/fxu/fxuMatrix.c \
+    src/opt/fxu/fxuPair.c \
+    src/opt/fxu/fxuPrint.c \
+    src/opt/fxu/fxuReduce.c \
+    src/opt/fxu/fxuSelect.c \
+    src/opt/fxu/fxuSingle.c \
+    src/opt/fxu/fxuUpdate.c
diff --git a/src/opt/lpk/lpk.h b/src/opt/lpk/lpk.h
new file mode 100644
index 00000000..2a642db2
--- /dev/null
+++ b/src/opt/lpk/lpk.h
@@ -0,0 +1,84 @@
+/**CFile****************************************************************
+
+  FileName    [lpk.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpk.h,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __LPK_H__
+#define __LPK_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif 
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Lpk_Par_t_ Lpk_Par_t;
+struct Lpk_Par_t_
+{
+    // user-controlled parameters
+    int               nLutsMax;      // (N) the maximum number of LUTs in the structure
+    int               nLutsOver;     // (Q) the maximum number of LUTs not in the MFFC
+    int               nVarsShared;   // (S) the maximum number of shared variables (crossbars)
+    int               nGrowthLevel;  // (L) the maximum increase in the node level after resynthesis
+    int               fSatur;        // iterate till saturation
+    int               fZeroCost;     // accept zero-cost replacements
+    int               fFirst;        // use root node and first cut only
+    int               fOldAlgo;      // use old algorithm
+    int               fVerbose;      // the verbosiness flag
+    int               fVeryVerbose;  // additional verbose info printout
+    // internal parameters
+    int               nLutSize;      // (K) the LUT size (determined by the input network)
+    int               nVarsMax;      // (V) the largest number of variables: V = N * (K-1) + 1
+};
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                           ITERATORS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== lpkCore.c ========================================================*/
+extern int     Lpk_Resynthesize( Abc_Ntk_t * pNtk, Lpk_Par_t * pPars );
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/lpk/lpkAbcDec.c b/src/opt/lpk/lpkAbcDec.c
new file mode 100644
index 00000000..aa2d4bc0
--- /dev/null
+++ b/src/opt/lpk/lpkAbcDec.c
@@ -0,0 +1,290 @@
+/**CFile****************************************************************
+
+  FileName    [lpkAbcDec.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    [The new core procedure.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkAbcDec.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Implements the function.]
+
+  Description [Returns the node implementing this function.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Lpk_ImplementFun( Lpk_Man_t * pMan, Abc_Ntk_t * pNtk, Vec_Ptr_t * vLeaves, Lpk_Fun_t * p )
+{
+    extern Hop_Obj_t * Kit_TruthToHop( Hop_Man_t * pMan, unsigned * pTruth, int nVars, Vec_Int_t * vMemory );
+    unsigned * pTruth;
+    Abc_Obj_t * pObjNew;
+    int i;
+    if ( p->fMark )
+        pMan->nMuxes++;
+    else
+        pMan->nDsds++;
+    // create the new node
+    pObjNew = Abc_NtkCreateNode( pNtk );
+    for ( i = 0; i < (int)p->nVars; i++ )
+        Abc_ObjAddFanin( pObjNew, Abc_ObjRegular(Vec_PtrEntry(vLeaves, p->pFanins[i])) );
+    Abc_ObjSetLevel( pObjNew, Abc_ObjLevelNew(pObjNew) );
+    // assign the node's function
+    pTruth = Lpk_FunTruth(p, 0);
+    if ( p->nVars == 0 )
+    {
+        pObjNew->pData = Hop_NotCond( Hop_ManConst1(pNtk->pManFunc), !(pTruth[0] & 1) );
+        return pObjNew;
+    }
+    if ( p->nVars == 1 )
+    {
+        pObjNew->pData = Hop_NotCond( Hop_ManPi(pNtk->pManFunc, 0), (pTruth[0] & 1) );
+        return pObjNew;
+    }
+    // create the logic function
+    pObjNew->pData = Kit_TruthToHop( pNtk->pManFunc, pTruth, p->nVars, NULL );
+    return pObjNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements the function.]
+
+  Description [Returns the node implementing this function.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Lpk_Implement_rec( Lpk_Man_t * pMan, Abc_Ntk_t * pNtk, Vec_Ptr_t * vLeaves, Lpk_Fun_t * pFun )
+{
+    Abc_Obj_t * pFanin, * pRes;
+    int i;
+    // prepare the leaves of the function
+    for ( i = 0; i < (int)pFun->nVars; i++ )
+    {
+        pFanin = Vec_PtrEntry( vLeaves, pFun->pFanins[i] );
+        if ( !Abc_ObjIsComplement(pFanin) )
+            Lpk_Implement_rec( pMan, pNtk, vLeaves, (Lpk_Fun_t *)pFanin );
+        pFanin = Vec_PtrEntry( vLeaves, pFun->pFanins[i] );
+        assert( Abc_ObjIsComplement(pFanin) );
+    }
+    // construct the function
+    pRes = Lpk_ImplementFun( pMan, pNtk, vLeaves, pFun );
+    // replace the function
+    Vec_PtrWriteEntry( vLeaves, pFun->Id, Abc_ObjNot(pRes) );
+    Lpk_FunFree( pFun );
+    return pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements the function.]
+
+  Description [Returns the node implementing this function.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Lpk_Implement( Lpk_Man_t * pMan, Abc_Ntk_t * pNtk, Vec_Ptr_t * vLeaves, int nLeavesOld )
+{
+    Abc_Obj_t * pFanin, * pRes;
+    int i;
+    assert( nLeavesOld < Vec_PtrSize(vLeaves) );
+    // mark implemented nodes
+    Vec_PtrForEachEntryStop( vLeaves, pFanin, i, nLeavesOld )
+        Vec_PtrWriteEntry( vLeaves, i, Abc_ObjNot(pFanin) );
+    // recursively construct starting from the first entry
+    pRes = Lpk_Implement_rec( pMan, pNtk, vLeaves, Vec_PtrEntry( vLeaves, nLeavesOld ) );
+    Vec_PtrShrink( vLeaves, nLeavesOld );
+    return pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Decomposes the function using recursive MUX decomposition.]
+
+  Description [Returns the ID of the top-most decomposition node 
+  implementing this function, or 0 if there is no decomposition satisfying
+  the constraints on area and delay.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_Decompose_rec( Lpk_Man_t * pMan, Lpk_Fun_t * p )
+{
+    static Lpk_Res_t Res0, * pRes0 = &Res0;
+    Lpk_Res_t * pResMux, * pResDsd;
+    Lpk_Fun_t * p2;
+    int clk;
+
+    // is only called for non-trivial blocks
+    assert( p->nLutK >= 3 && p->nLutK <= 6 );
+    assert( p->nVars > p->nLutK );
+    // skip if area bound is exceeded
+    if ( Lpk_LutNumLuts(p->nVars, p->nLutK) > (int)p->nAreaLim )
+        return 0;
+    // skip if delay bound is exceeded
+    if ( Lpk_SuppDelay(p->uSupp, p->pDelays) > (int)p->nDelayLim )
+        return 0;
+
+    // compute supports if needed
+    if ( !p->fSupports )
+        Lpk_FunComputeCofSupps( p );
+
+    // check DSD decomposition
+clk = clock();
+    pResDsd = Lpk_DsdAnalize( pMan, p, pMan->pPars->nVarsShared );
+pMan->timeEvalDsdAn += clock() - clk;
+    if ( pResDsd && (pResDsd->nBSVars == (int)p->nLutK || pResDsd->nBSVars == (int)p->nLutK - 1) && 
+          pResDsd->AreaEst <= (int)p->nAreaLim && pResDsd->DelayEst <= (int)p->nDelayLim )
+    {
+clk = clock();
+        p2 = Lpk_DsdSplit( pMan, p, pResDsd->pCofVars, pResDsd->nCofVars, pResDsd->BSVars );
+pMan->timeEvalDsdSp += clock() - clk;
+        assert( p2->nVars <= (int)p->nLutK );
+        if ( p->nVars > p->nLutK && !Lpk_Decompose_rec( pMan, p ) )
+            return 0;
+        return 1;
+    }
+
+    // check MUX decomposition
+clk = clock();
+    pResMux = Lpk_MuxAnalize( pMan, p );
+pMan->timeEvalMuxAn += clock() - clk;
+//    pResMux = NULL;
+    assert( !pResMux || (pResMux->DelayEst <= (int)p->nDelayLim && pResMux->AreaEst <= (int)p->nAreaLim) );
+    // accept MUX decomposition if it is "good"
+    if ( pResMux && pResMux->nSuppSizeS <= (int)p->nLutK && pResMux->nSuppSizeL <= (int)p->nLutK )
+        pResDsd = NULL;
+    else if ( pResMux && pResDsd )
+    {
+        // compare two decompositions
+        if ( pResMux->AreaEst < pResDsd->AreaEst || 
+            (pResMux->AreaEst == pResDsd->AreaEst && pResMux->nSuppSizeL < pResDsd->nSuppSizeL) || 
+            (pResMux->AreaEst == pResDsd->AreaEst && pResMux->nSuppSizeL == pResDsd->nSuppSizeL && pResMux->DelayEst < pResDsd->DelayEst) )
+            pResDsd = NULL;
+        else
+            pResMux = NULL;
+    }
+    assert( pResMux == NULL || pResDsd == NULL );
+    if ( pResMux )
+    {
+clk = clock();
+        p2 = Lpk_MuxSplit( pMan, p, pResMux->Variable, pResMux->Polarity );
+pMan->timeEvalMuxSp += clock() - clk;
+        if ( p2->nVars > p->nLutK && !Lpk_Decompose_rec( pMan, p2 ) )
+            return 0;
+        if ( p->nVars > p->nLutK && !Lpk_Decompose_rec( pMan, p ) )
+            return 0;
+        return 1;
+    }
+    if ( pResDsd )
+    {
+clk = clock();
+        p2 = Lpk_DsdSplit( pMan, p, pResDsd->pCofVars, pResDsd->nCofVars, pResDsd->BSVars );
+pMan->timeEvalDsdSp += clock() - clk;
+        assert( p2->nVars <= (int)p->nLutK );
+        if ( p->nVars > p->nLutK && !Lpk_Decompose_rec( pMan, p ) )
+            return 0;
+        return 1;
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Removes decomposed nodes from the array of fanins.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_DecomposeClean( Vec_Ptr_t * vLeaves, int nLeavesOld )
+{
+    Lpk_Fun_t * pFunc;
+    int i;
+    Vec_PtrForEachEntryStart( vLeaves, pFunc, i, nLeavesOld )
+        Lpk_FunFree( pFunc );
+    Vec_PtrShrink( vLeaves, nLeavesOld );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Decomposes the function using recursive MUX decomposition.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Lpk_Decompose( Lpk_Man_t * p, Abc_Ntk_t * pNtk, Vec_Ptr_t * vLeaves, unsigned * pTruth, unsigned * puSupps, int nLutK, int AreaLim, int DelayLim )
+{
+    Lpk_Fun_t * pFun;
+    Abc_Obj_t * pObjNew = NULL;
+    int nLeaves = Vec_PtrSize( vLeaves );
+    pFun = Lpk_FunCreate( pNtk, vLeaves, pTruth, nLutK, AreaLim, DelayLim );
+    if ( puSupps[0] || puSupps[1] )
+    {
+/*
+        int i;
+        Lpk_FunComputeCofSupps( pFun );
+        for ( i = 0; i < nLeaves; i++ )
+        {
+            assert( pFun->puSupps[2*i+0] == puSupps[2*i+0] );
+            assert( pFun->puSupps[2*i+1] == puSupps[2*i+1] );
+        }
+*/
+        memcpy( pFun->puSupps, puSupps, sizeof(unsigned) * 2 * nLeaves );
+        pFun->fSupports = 1;
+    }
+    Lpk_FunSuppMinimize( pFun );
+    if ( pFun->nVars <= pFun->nLutK )
+        pObjNew = Lpk_ImplementFun( p, pNtk, vLeaves, pFun );
+    else if ( Lpk_Decompose_rec(p, pFun) )
+        pObjNew = Lpk_Implement( p, pNtk, vLeaves, nLeaves );
+    Lpk_DecomposeClean( vLeaves, nLeaves );
+    return pObjNew;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkAbcDsd.c b/src/opt/lpk/lpkAbcDsd.c
new file mode 100644
index 00000000..f4095914
--- /dev/null
+++ b/src/opt/lpk/lpkAbcDsd.c
@@ -0,0 +1,603 @@
+/**CFile****************************************************************
+
+  FileName    [lpkAbcDsd.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    [LUT-decomposition based on recursive DSD.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkAbcDsd.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Cofactors TTs w.r.t. all vars and finds the best var.]
+
+  Description [The best variable is the variable with the minimum 
+  sum total of the support sizes of all truth tables. This procedure 
+  computes and returns cofactors w.r.t. the best variable.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_FunComputeMinSuppSizeVar( Lpk_Fun_t * p, unsigned ** ppTruths, int nTruths, unsigned ** ppCofs, unsigned uNonDecSupp )
+{
+    int i, Var, VarBest, nSuppSize0, nSuppSize1, nSuppTotalMin, nSuppTotalCur, nSuppMaxMin, nSuppMaxCur;
+    assert( nTruths > 0 );
+    VarBest = -1;
+    Lpk_SuppForEachVar( p->uSupp, Var )
+    {
+        if ( (uNonDecSupp & (1 << Var)) == 0 )
+            continue;
+        nSuppMaxCur = 0;
+        nSuppTotalCur = 0;
+        for ( i = 0; i < nTruths; i++ )
+        {
+            if ( nTruths == 1 )
+            {
+                nSuppSize0 = Kit_WordCountOnes( p->puSupps[2*Var+0] );
+                nSuppSize1 = Kit_WordCountOnes( p->puSupps[2*Var+1] );
+            }
+            else
+            {
+                Kit_TruthCofactor0New( ppCofs[2*i+0], ppTruths[i], p->nVars, Var );
+                Kit_TruthCofactor1New( ppCofs[2*i+1], ppTruths[i], p->nVars, Var );
+                nSuppSize0 = Kit_TruthSupportSize( ppCofs[2*i+0], p->nVars );
+                nSuppSize1 = Kit_TruthSupportSize( ppCofs[2*i+1], p->nVars );
+            }        
+            nSuppMaxCur = ABC_MAX( nSuppMaxCur, nSuppSize0 );
+            nSuppMaxCur = ABC_MAX( nSuppMaxCur, nSuppSize1 );
+            nSuppTotalCur += nSuppSize0 + nSuppSize1;
+        }
+        if ( VarBest == -1 || nSuppMaxMin > nSuppMaxCur ||
+             (nSuppMaxMin == nSuppMaxCur && nSuppTotalMin > nSuppTotalCur) )
+        {
+            VarBest = Var;
+            nSuppMaxMin = nSuppMaxCur;
+            nSuppTotalMin = nSuppTotalCur;
+        }
+    }
+    // recompute cofactors for the best var
+    for ( i = 0; i < nTruths; i++ )
+    {
+        Kit_TruthCofactor0New( ppCofs[2*i+0], ppTruths[i], p->nVars, VarBest );
+        Kit_TruthCofactor1New( ppCofs[2*i+1], ppTruths[i], p->nVars, VarBest );
+    }
+    return VarBest;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively computes decomposable subsets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Lpk_ComputeBoundSets_rec( Kit_DsdNtk_t * p, int iLit, Vec_Int_t * vSets, int nSizeMax )
+{
+    unsigned i, iLitFanin, uSupport, uSuppCur;
+    Kit_DsdObj_t * pObj;
+    // consider the case of simple gate
+    pObj = Kit_DsdNtkObj( p, Kit_DsdLit2Var(iLit) );
+    if ( pObj == NULL )
+        return (1 << Kit_DsdLit2Var(iLit));
+    if ( pObj->Type == KIT_DSD_AND || pObj->Type == KIT_DSD_XOR )
+    {
+        unsigned uSupps[16], Limit, s;
+        uSupport = 0;
+        Kit_DsdObjForEachFanin( p, pObj, iLitFanin, i )
+        {
+            uSupps[i] = Lpk_ComputeBoundSets_rec( p, iLitFanin, vSets, nSizeMax );
+            uSupport |= uSupps[i];
+        }
+        // create all subsets, except empty and full
+        Limit = (1 << pObj->nFans) - 1;
+        for ( s = 1; s < Limit; s++ )
+        {
+            uSuppCur = 0;
+            for ( i = 0; i < pObj->nFans; i++ )
+                if ( s & (1 << i) )
+                    uSuppCur |= uSupps[i];
+            if ( Kit_WordCountOnes(uSuppCur) <= nSizeMax )
+                Vec_IntPush( vSets, uSuppCur );
+        }
+        return uSupport;
+    }
+    assert( pObj->Type == KIT_DSD_PRIME );
+    // get the cumulative support of all fanins
+    uSupport = 0;
+    Kit_DsdObjForEachFanin( p, pObj, iLitFanin, i )
+    {
+        uSuppCur  = Lpk_ComputeBoundSets_rec( p, iLitFanin, vSets, nSizeMax );
+        uSupport |= uSuppCur;
+        if ( Kit_WordCountOnes(uSuppCur) <= nSizeMax )
+            Vec_IntPush( vSets, uSuppCur );
+    }
+    return uSupport;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the set of subsets of decomposable variables.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Lpk_ComputeBoundSets( Kit_DsdNtk_t * p, int nSizeMax )
+{
+    Vec_Int_t * vSets;
+    unsigned uSupport, Entry;
+    int Number, i;
+    assert( p->nVars <= 16 );
+    vSets = Vec_IntAlloc( 100 );
+    Vec_IntPush( vSets, 0 );
+    if ( Kit_DsdNtkRoot(p)->Type == KIT_DSD_CONST1 )
+        return vSets;
+    if ( Kit_DsdNtkRoot(p)->Type == KIT_DSD_VAR )
+    {
+        uSupport = ( 1 << Kit_DsdLit2Var(Kit_DsdNtkRoot(p)->pFans[0]) );
+        if ( Kit_WordCountOnes(uSupport) <= nSizeMax )
+            Vec_IntPush( vSets, uSupport );
+        return vSets;
+    }
+    uSupport = Lpk_ComputeBoundSets_rec( p, p->Root, vSets, nSizeMax );
+    assert( (uSupport & 0xFFFF0000) == 0 );
+    // add the total support of the network
+    if ( Kit_WordCountOnes(uSupport) <= nSizeMax )
+        Vec_IntPush( vSets, uSupport );
+    // set the remaining variables
+    Vec_IntForEachEntry( vSets, Number, i )
+    {
+        Entry = Number;
+        Vec_IntWriteEntry( vSets, i, Entry | ((uSupport & ~Entry) << 16) );
+    }
+    return vSets;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the sets of subsets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static void Lpk_PrintSetOne( int uSupport )
+{
+    unsigned k;
+    for ( k = 0; k < 16; k++ )
+        if ( uSupport & (1<<k) )
+            printf( "%c", 'a'+k );
+    printf( " " );
+}
+/**Function*************************************************************
+
+  Synopsis    [Prints the sets of subsets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static void Lpk_PrintSets( Vec_Int_t * vSets )
+{
+    unsigned uSupport;
+    int Number, i;
+    printf( "Subsets(%d): ", Vec_IntSize(vSets) );
+    Vec_IntForEachEntry( vSets, Number, i )
+    {
+        uSupport = Number;
+        Lpk_PrintSetOne( uSupport );
+    }
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Merges two bound sets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Lpk_MergeBoundSets( Vec_Int_t * vSets0, Vec_Int_t * vSets1, int nSizeMax )
+{
+    Vec_Int_t * vSets;
+    int Entry0, Entry1, Entry;
+    int i, k;
+    vSets = Vec_IntAlloc( 100 );
+    Vec_IntForEachEntry( vSets0, Entry0, i )
+    Vec_IntForEachEntry( vSets1, Entry1, k )
+    {
+        Entry = Entry0 | Entry1;
+        if ( (Entry & (Entry >> 16)) )
+            continue;
+        if ( Kit_WordCountOnes(Entry & 0xffff) <= nSizeMax )
+            Vec_IntPush( vSets, Entry );
+    }
+    return vSets;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs DSD-based decomposition of the function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_FunCompareBoundSets( Lpk_Fun_t * p, Vec_Int_t * vBSets, int nCofDepth, unsigned uNonDecSupp, unsigned uLateArrSupp, Lpk_Res_t * pRes )
+{
+    int fVerbose = 0;
+    unsigned uBoundSet;
+    int i, nVarsBS, nVarsRem, Delay, Area;
+
+    // compare the resulting boundsets
+    memset( pRes, 0, sizeof(Lpk_Res_t) );
+    Vec_IntForEachEntry( vBSets, uBoundSet, i )
+    {
+        if ( (uBoundSet & 0xFFFF) == 0 ) // skip empty boundset
+            continue;
+        if ( (uBoundSet & uNonDecSupp) == 0 ) // skip those boundsets that are not in the domain of interest
+            continue;
+        if ( (uBoundSet & uLateArrSupp) ) // skip those boundsets that are late arriving
+            continue;
+if ( fVerbose )
+Lpk_PrintSetOne( uBoundSet );
+        assert( (uBoundSet & (uBoundSet >> 16)) == 0 );
+        nVarsBS = Kit_WordCountOnes( uBoundSet & 0xFFFF );
+        if ( nVarsBS == 1 )
+            continue;
+        assert( nVarsBS <= (int)p->nLutK - nCofDepth );
+        nVarsRem = p->nVars - nVarsBS + 1;
+        Area = 1 + Lpk_LutNumLuts( nVarsRem, p->nLutK );
+        Delay = 1 + Lpk_SuppDelay( uBoundSet & 0xFFFF, p->pDelays );
+if ( fVerbose )
+printf( "area = %d limit = %d  delay = %d limit = %d\n", Area, (int)p->nAreaLim, Delay, (int)p->nDelayLim );
+        if ( Area > (int)p->nAreaLim || Delay > (int)p->nDelayLim )
+            continue;
+        if ( pRes->BSVars == 0 || pRes->nSuppSizeL > nVarsRem || (pRes->nSuppSizeL == nVarsRem && pRes->DelayEst > Delay) )
+        {
+            pRes->nBSVars = nVarsBS;
+            pRes->BSVars = (uBoundSet & 0xFFFF);
+            pRes->nSuppSizeS = nVarsBS + nCofDepth;
+            pRes->nSuppSizeL = nVarsRem;
+            pRes->DelayEst = Delay;
+            pRes->AreaEst = Area;
+        }
+    }
+if ( fVerbose )
+{
+if ( pRes->BSVars )
+{
+printf( "Found bound set " );
+Lpk_PrintSetOne( pRes->BSVars );
+printf( "\n" );
+}
+else
+printf( "Did not find boundsets.\n" );
+printf( "\n" );
+}
+    if ( pRes->BSVars )
+    {
+        assert( pRes->DelayEst <= (int)p->nDelayLim );
+        assert( pRes->AreaEst <= (int)p->nAreaLim );
+    }
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Finds late arriving inputs, which cannot be in the bound set.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Lpk_DsdLateArriving( Lpk_Fun_t * p )
+{
+    unsigned i, uLateArrSupp = 0;
+    Lpk_SuppForEachVar( p->uSupp, i )
+        if ( p->pDelays[i] > (int)p->nDelayLim - 2 )
+            uLateArrSupp |= (1 << i);  
+    return uLateArrSupp;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs DSD-based decomposition of the function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_DsdAnalizeOne( Lpk_Fun_t * p, unsigned * ppTruths[5][16], Kit_DsdNtk_t * pNtks[], char pCofVars[], int nCofDepth, Lpk_Res_t * pRes )
+{
+    int fVerbose = 0;
+    Vec_Int_t * pvBSets[4][8];
+    unsigned uNonDecSupp, uLateArrSupp;
+    int i, k, nNonDecSize, nNonDecSizeMax;
+    assert( nCofDepth >= 1 && nCofDepth <= 3 );
+    assert( nCofDepth < (int)p->nLutK - 1 );
+    assert( p->fSupports );
+
+    // find the support of the largest non-DSD block
+    nNonDecSizeMax = 0;
+    uNonDecSupp = p->uSupp;
+    for ( i = 0; i < (1<<(nCofDepth-1)); i++ )
+    {
+        nNonDecSize = Kit_DsdNonDsdSizeMax( pNtks[i] );
+        if ( nNonDecSizeMax < nNonDecSize )
+        {
+            nNonDecSizeMax = nNonDecSize;
+            uNonDecSupp = Kit_DsdNonDsdSupports( pNtks[i] );
+        }
+        else if ( nNonDecSizeMax == nNonDecSize )
+            uNonDecSupp |= Kit_DsdNonDsdSupports( pNtks[i] );
+    }
+
+    // remove those variables that cannot be used because of delay constraints
+    // if variables arrival time is more than p->DelayLim - 2, it cannot be used
+    uLateArrSupp = Lpk_DsdLateArriving( p );
+    if ( (uNonDecSupp & ~uLateArrSupp) == 0 )
+    {
+        memset( pRes, 0, sizeof(Lpk_Res_t) );
+        return 0;
+    }
+
+    // find the next cofactoring variable
+    pCofVars[nCofDepth-1] = Lpk_FunComputeMinSuppSizeVar( p, ppTruths[nCofDepth-1], 1<<(nCofDepth-1), ppTruths[nCofDepth], uNonDecSupp & ~uLateArrSupp );
+
+    // derive decomposed networks
+    for ( i = 0; i < (1<<nCofDepth); i++ )
+    {
+        if ( pNtks[i] )
+            Kit_DsdNtkFree( pNtks[i] );
+        pNtks[i] = Kit_DsdDecomposeExpand( ppTruths[nCofDepth][i], p->nVars );
+if ( fVerbose )
+Kit_DsdPrint( stdout, pNtks[i] );
+        pvBSets[nCofDepth][i] = Lpk_ComputeBoundSets( pNtks[i], p->nLutK - nCofDepth ); // try restricting to those in uNonDecSupp!!!
+    }
+
+    // derive the set of feasible boundsets
+    for ( i = nCofDepth - 1; i >= 0; i-- )
+        for ( k = 0; k < (1<<i); k++ )
+            pvBSets[i][k] = Lpk_MergeBoundSets( pvBSets[i+1][2*k+0], pvBSets[i+1][2*k+1], p->nLutK - nCofDepth );
+    // compare bound-sets
+    Lpk_FunCompareBoundSets( p, pvBSets[0][0], nCofDepth, uNonDecSupp, uLateArrSupp, pRes );
+    // free the bound sets
+    for ( i = nCofDepth; i >= 0; i-- )
+        for ( k = 0; k < (1<<i); k++ )
+            Vec_IntFree( pvBSets[i][k] );
+ 
+    // copy the cofactoring variables
+    if ( pRes->BSVars )
+    {
+        pRes->nCofVars = nCofDepth;
+        for ( i = 0; i < nCofDepth; i++ )
+            pRes->pCofVars[i] = pCofVars[i];
+    }
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs DSD-based decomposition of the function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Res_t * Lpk_DsdAnalize( Lpk_Man_t * pMan, Lpk_Fun_t * p, int nShared )
+{ 
+    static Lpk_Res_t Res0, * pRes0 = &Res0;
+    static Lpk_Res_t Res1, * pRes1 = &Res1;
+    static Lpk_Res_t Res2, * pRes2 = &Res2;
+    static Lpk_Res_t Res3, * pRes3 = &Res3;
+    int fUseBackLooking = 1;
+    Lpk_Res_t * pRes = NULL;
+    Vec_Int_t * vBSets;
+    Kit_DsdNtk_t * pNtks[8] = {NULL};
+    char pCofVars[5];
+    int i;
+
+    assert( p->nLutK >= 3 );
+    assert( nShared >= 0 && nShared <= 3 );
+    assert( p->uSupp == Kit_BitMask(p->nVars) );
+
+    // try decomposition without cofactoring
+    pNtks[0] = Kit_DsdDecomposeExpand( Lpk_FunTruth( p, 0 ), p->nVars );
+    if ( pMan->pPars->fVerbose )
+        pMan->nBlocks[ Kit_DsdNonDsdSizeMax(pNtks[0]) ]++;
+    vBSets = Lpk_ComputeBoundSets( pNtks[0], p->nLutK );
+    Lpk_FunCompareBoundSets( p, vBSets, 0, 0xFFFF, Lpk_DsdLateArriving(p), pRes0 );
+    Vec_IntFree( vBSets );
+
+    // check the result
+    if ( pRes0->nBSVars == (int)p->nLutK )
+        { pRes = pRes0; goto finish; }
+    if ( pRes0->nBSVars == (int)p->nLutK - 1 )
+        { pRes = pRes0; goto finish; }
+    if ( nShared == 0 )
+        goto finish;
+
+    // prepare storage
+    Kit_TruthCopy( pMan->ppTruths[0][0], Lpk_FunTruth( p, 0 ), p->nVars );
+
+    // cofactor 1 time
+    if ( !Lpk_DsdAnalizeOne( p, pMan->ppTruths, pNtks, pCofVars, 1, pRes1 ) )
+        goto finish;
+    assert( pRes1->nBSVars <= (int)p->nLutK - 1 );
+    if ( pRes1->nBSVars == (int)p->nLutK - 1 )
+        { pRes = pRes1; goto finish; }
+    if ( pRes0->nBSVars == (int)p->nLutK - 2 )
+        { pRes = pRes0; goto finish; }
+    if ( pRes1->nBSVars == (int)p->nLutK - 2 )
+        { pRes = pRes1; goto finish; }
+    if ( nShared == 1 )
+        goto finish;
+
+    // cofactor 2 times
+    if ( p->nLutK >= 4 ) 
+    {
+        if ( !Lpk_DsdAnalizeOne( p, pMan->ppTruths, pNtks, pCofVars, 2, pRes2 ) )
+            goto finish;
+        assert( pRes2->nBSVars <= (int)p->nLutK - 2 );
+        if ( pRes2->nBSVars == (int)p->nLutK - 2 )
+            { pRes = pRes2; goto finish; }
+        if ( fUseBackLooking )
+        {
+            if ( pRes0->nBSVars == (int)p->nLutK - 3 )
+                { pRes = pRes0; goto finish; }
+            if ( pRes1->nBSVars == (int)p->nLutK - 3 )
+                { pRes = pRes1; goto finish; }
+        }
+        if ( pRes2->nBSVars == (int)p->nLutK - 3 )
+            { pRes = pRes2; goto finish; }
+        if ( nShared == 2 )
+            goto finish;
+        assert( nShared == 3 );
+    }
+
+    // cofactor 3 times
+    if ( p->nLutK >= 5 ) 
+    {
+        if ( !Lpk_DsdAnalizeOne( p, pMan->ppTruths, pNtks, pCofVars, 3, pRes3 ) )
+            goto finish;
+        assert( pRes3->nBSVars <= (int)p->nLutK - 3 );
+        if ( pRes3->nBSVars == (int)p->nLutK - 3 )
+            { pRes = pRes3; goto finish; }
+        if ( fUseBackLooking )
+        {
+            if ( pRes0->nBSVars == (int)p->nLutK - 4 )
+                { pRes = pRes0; goto finish; }
+            if ( pRes1->nBSVars == (int)p->nLutK - 4 )
+                { pRes = pRes1; goto finish; }
+            if ( pRes2->nBSVars == (int)p->nLutK - 4 )
+                { pRes = pRes2; goto finish; }
+        }
+        if ( pRes3->nBSVars == (int)p->nLutK - 4 )
+            { pRes = pRes3; goto finish; }
+    }
+
+finish:
+    // free the networks
+    for ( i = 0; i < (1<<nShared); i++ )
+        if ( pNtks[i] )
+            Kit_DsdNtkFree( pNtks[i] );
+    // choose the best under these conditions
+    return pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Splits the function into two subfunctions using DSD.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Fun_t * Lpk_DsdSplit( Lpk_Man_t * pMan, Lpk_Fun_t * p, char * pCofVars, int nCofVars, unsigned uBoundSet )
+{
+    Lpk_Fun_t * pNew;
+    Kit_DsdNtk_t * pNtkDec;
+    int i, k, iVacVar, nCofs;
+    // prepare storage
+    Kit_TruthCopy( pMan->ppTruths[0][0], Lpk_FunTruth(p, 0), p->nVars );
+    // get the vacuous variable
+    iVacVar = Kit_WordFindFirstBit( uBoundSet );
+    // compute the cofactors
+    for ( i = 0; i < nCofVars; i++ )
+        for ( k = 0; k < (1<<i); k++ )
+        {
+            Kit_TruthCofactor0New( pMan->ppTruths[i+1][2*k+0], pMan->ppTruths[i][k], p->nVars, pCofVars[i] );
+            Kit_TruthCofactor1New( pMan->ppTruths[i+1][2*k+1], pMan->ppTruths[i][k], p->nVars, pCofVars[i] );
+        }
+    // decompose each cofactor w.r.t. the bound set
+    nCofs = (1<<nCofVars);
+    for ( k = 0; k < nCofs; k++ )
+    {
+        pNtkDec = Kit_DsdDecomposeExpand( pMan->ppTruths[nCofVars][k], p->nVars );
+        Kit_DsdTruthPartialTwo( pMan->pDsdMan, pNtkDec, uBoundSet, iVacVar, pMan->ppTruths[nCofVars+1][k], pMan->ppTruths[nCofVars+1][nCofs+k] );
+        Kit_DsdNtkFree( pNtkDec );
+    }
+    // compute the composition/decomposition functions (they will be in pMan->ppTruths[1][0]/pMan->ppTruths[1][1])
+    for ( i = nCofVars; i >= 1; i-- )
+        for ( k = 0; k < (1<<i); k++ )
+            Kit_TruthMuxVar( pMan->ppTruths[i][k], pMan->ppTruths[i+1][2*k+0], pMan->ppTruths[i+1][2*k+1], p->nVars, pCofVars[i-1] );
+
+    // derive the new component (decomposition function)
+    pNew = Lpk_FunDup( p, pMan->ppTruths[1][1] );
+    // update the old component (composition function)
+    Kit_TruthCopy( Lpk_FunTruth(p, 0), pMan->ppTruths[1][0], p->nVars );
+    p->uSupp = Kit_TruthSupport( Lpk_FunTruth(p, 0), p->nVars );
+    p->pFanins[iVacVar] = pNew->Id;
+    p->pDelays[iVacVar] = Lpk_SuppDelay( pNew->uSupp, pNew->pDelays );
+    // support minimize both
+    p->fSupports = 0;
+    Lpk_FunSuppMinimize( p );
+    Lpk_FunSuppMinimize( pNew );
+    // update delay and area requirements
+    pNew->nDelayLim = p->pDelays[iVacVar];
+    pNew->nAreaLim = 1;
+    p->nAreaLim = p->nAreaLim - 1;
+    return pNew;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkAbcMux.c b/src/opt/lpk/lpkAbcMux.c
new file mode 100644
index 00000000..d6f579ee
--- /dev/null
+++ b/src/opt/lpk/lpkAbcMux.c
@@ -0,0 +1,235 @@
+/**CFile****************************************************************
+
+  FileName    [lpkAbcMux.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    [LUT-decomposition based on recursive MUX decomposition.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkAbcMux.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Checks the possibility of MUX decomposition.]
+
+  Description [Returns the best variable to use for MUX decomposition.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Res_t * Lpk_MuxAnalize( Lpk_Man_t * pMan, Lpk_Fun_t * p )
+{
+    static Lpk_Res_t Res, * pRes = &Res;
+    int nSuppSize0, nSuppSize1, nSuppSizeS, nSuppSizeL;
+    int Var, Area, Polarity, Delay, Delay0, Delay1, DelayA, DelayB;
+    memset( pRes, 0, sizeof(Lpk_Res_t) );
+    assert( p->uSupp == Kit_BitMask(p->nVars) );
+    assert( p->fSupports );
+    // derive the delay and area after MUX-decomp with each var - and find the best var
+    pRes->Variable = -1;
+    Lpk_SuppForEachVar( p->uSupp, Var )
+    {
+        nSuppSize0 = Kit_WordCountOnes(p->puSupps[2*Var+0]);
+        nSuppSize1 = Kit_WordCountOnes(p->puSupps[2*Var+1]);
+        assert( nSuppSize0 < (int)p->nVars );
+        assert( nSuppSize1 < (int)p->nVars );
+        if ( nSuppSize0 < 1 || nSuppSize1 < 1 )
+            continue;
+//printf( "%d %d    ", nSuppSize0, nSuppSize1 );
+        if ( nSuppSize0 <= (int)p->nLutK - 2 && nSuppSize1 <= (int)p->nLutK - 2 )
+        {
+            // include cof var into 0-block
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+0] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+1]           , p->pDelays );
+            Delay0 = ABC_MAX( DelayA, DelayB + 1 );
+            // include cof var into 1-block
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+1] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+0]           , p->pDelays );
+            Delay1 = ABC_MAX( DelayA, DelayB + 1 );
+            // get the best delay
+            Delay = ABC_MIN( Delay0, Delay1 );
+            Area = 2;
+            Polarity = (int)(Delay == Delay1);
+        }
+        else if ( nSuppSize0 <= (int)p->nLutK - 2 )
+        {
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+0] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+1]           , p->pDelays );
+            Delay = ABC_MAX( DelayA, DelayB + 1 );
+            Area = 1 + Lpk_LutNumLuts( nSuppSize1, p->nLutK );
+            Polarity = 0;
+        }
+        else if ( nSuppSize1 <= (int)p->nLutK - 2 )
+        {
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+1] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+0]           , p->pDelays );
+            Delay = ABC_MAX( DelayA, DelayB + 1 );
+            Area = 1 + Lpk_LutNumLuts( nSuppSize0, p->nLutK );
+            Polarity = 1;
+        }
+        else if ( nSuppSize0 <= (int)p->nLutK )
+        {
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+1] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+0]           , p->pDelays );
+            Delay = ABC_MAX( DelayA, DelayB + 1 );
+            Area = 1 + Lpk_LutNumLuts( nSuppSize1+2, p->nLutK );
+            Polarity = 1;
+        }
+        else if ( nSuppSize1 <= (int)p->nLutK )
+        {
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+0] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+1]           , p->pDelays );
+            Delay = ABC_MAX( DelayA, DelayB + 1 );
+            Area = 1 + Lpk_LutNumLuts( nSuppSize0+2, p->nLutK );
+            Polarity = 0;
+        }
+        else
+        {
+            // include cof var into 0-block
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+0] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+1]           , p->pDelays );
+            Delay0 = ABC_MAX( DelayA, DelayB + 1 );
+            // include cof var into 1-block
+            DelayA = Lpk_SuppDelay( p->puSupps[2*Var+1] | (1<<Var), p->pDelays );
+            DelayB = Lpk_SuppDelay( p->puSupps[2*Var+0]           , p->pDelays );
+            Delay1 = ABC_MAX( DelayA, DelayB + 1 );
+            // get the best delay
+            Delay = ABC_MIN( Delay0, Delay1 );
+            if ( Delay == Delay0 )
+                Area = Lpk_LutNumLuts( nSuppSize0+2, p->nLutK ) + Lpk_LutNumLuts( nSuppSize1, p->nLutK );
+            else
+                Area = Lpk_LutNumLuts( nSuppSize1+2, p->nLutK ) + Lpk_LutNumLuts( nSuppSize0, p->nLutK );
+            Polarity = (int)(Delay == Delay1);
+        }
+        // find the best variable
+        if ( Delay > (int)p->nDelayLim )
+            continue;
+        if ( Area > (int)p->nAreaLim )
+            continue;
+        nSuppSizeS = ABC_MIN( nSuppSize0 + 2 *!Polarity, nSuppSize1 + 2 * Polarity );
+        nSuppSizeL = ABC_MAX( nSuppSize0 + 2 *!Polarity, nSuppSize1 + 2 * Polarity );
+        if ( nSuppSizeL > (int)p->nVars )
+            continue;
+        if ( pRes->Variable == -1 || pRes->AreaEst > Area || 
+            (pRes->AreaEst == Area && pRes->nSuppSizeS + pRes->nSuppSizeL > nSuppSizeS + nSuppSizeL) || 
+            (pRes->AreaEst == Area && pRes->nSuppSizeS + pRes->nSuppSizeL == nSuppSizeS + nSuppSizeL && pRes->DelayEst > Delay) )
+        {
+            pRes->Variable = Var;
+            pRes->Polarity = Polarity;
+            pRes->AreaEst  = Area;
+            pRes->DelayEst = Delay;
+            pRes->nSuppSizeS = nSuppSizeS;
+            pRes->nSuppSizeL = nSuppSizeL;
+        }
+    }
+    return pRes->Variable == -1 ? NULL : pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the function decomposed by the MUX decomposition.]
+
+  Description [Returns the best variable to use for MUX decomposition.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Fun_t * Lpk_MuxSplit( Lpk_Man_t * pMan, Lpk_Fun_t * p, int Var, int Pol )
+{
+    Lpk_Fun_t * pNew;
+    unsigned * pTruth  = Lpk_FunTruth( p, 0 );
+    unsigned * pTruth0 = Lpk_FunTruth( p, 1 );
+    unsigned * pTruth1 = Lpk_FunTruth( p, 2 );
+//    unsigned uSupp;
+    int iVarVac; 
+    assert( Var >= 0 && Var < (int)p->nVars );
+    assert( p->nAreaLim >= 2 );
+    assert( p->uSupp == Kit_BitMask(p->nVars) );
+    Kit_TruthCofactor0New( pTruth0, pTruth, p->nVars, Var );
+    Kit_TruthCofactor1New( pTruth1, pTruth, p->nVars, Var );
+/*
+uSupp = Kit_TruthSupport( pTruth, p->nVars );
+Extra_PrintBinary( stdout, &uSupp, 16 ); printf( "\n" );
+uSupp = Kit_TruthSupport( pTruth0, p->nVars );
+Extra_PrintBinary( stdout, &uSupp, 16 ); printf( "\n" );
+uSupp = Kit_TruthSupport( pTruth1, p->nVars );
+Extra_PrintBinary( stdout, &uSupp, 16 ); printf( "\n\n" );
+*/
+    // derive the new component
+    pNew = Lpk_FunDup( p, Pol ? pTruth0 : pTruth1 );
+    // update the support of the old component
+    p->uSupp  = Kit_TruthSupport( Pol ? pTruth1 : pTruth0, p->nVars );
+    p->uSupp |= (1 << Var);
+    // update the truth table of the old component
+    iVarVac = Kit_WordFindFirstBit( ~p->uSupp );
+    assert( iVarVac < (int)p->nVars );
+    p->uSupp |= (1 << iVarVac);
+    Kit_TruthIthVar( pTruth, p->nVars, iVarVac );
+    if ( Pol )
+        Kit_TruthMuxVar( pTruth, pTruth, pTruth1, p->nVars, Var );
+    else
+        Kit_TruthMuxVar( pTruth, pTruth0, pTruth, p->nVars, Var );
+    assert( p->uSupp == Kit_TruthSupport(pTruth, p->nVars) );
+    // set the decomposed variable
+    p->pFanins[iVarVac] = pNew->Id;
+    p->pDelays[iVarVac] = p->nDelayLim - 1;
+    // support minimize both
+    p->fSupports = 0;
+    Lpk_FunSuppMinimize( p );
+    Lpk_FunSuppMinimize( pNew );
+    // update delay and area requirements
+    pNew->nDelayLim = p->nDelayLim - 1;
+    if ( pNew->nVars <= pNew->nLutK )
+    {
+        pNew->nAreaLim = 1;
+        p->nAreaLim = p->nAreaLim - 1;
+    }
+    else if ( p->nVars <= p->nLutK )
+    {
+        pNew->nAreaLim = p->nAreaLim - 1;
+        p->nAreaLim = 1;
+    }
+    else if ( p->nVars < pNew->nVars )
+    {
+        pNew->nAreaLim = p->nAreaLim / 2 + p->nAreaLim % 2;
+        p->nAreaLim = p->nAreaLim / 2 - p->nAreaLim % 2;
+    }
+    else // if ( pNew->nVars < p->nVars )
+    {
+        pNew->nAreaLim = p->nAreaLim / 2 - p->nAreaLim % 2;
+        p->nAreaLim = p->nAreaLim / 2 + p->nAreaLim % 2;
+    }
+    pNew->fMark = 1;
+    return pNew;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkAbcUtil.c b/src/opt/lpk/lpkAbcUtil.c
new file mode 100644
index 00000000..3f917ce2
--- /dev/null
+++ b/src/opt/lpk/lpkAbcUtil.c
@@ -0,0 +1,244 @@
+/**CFile****************************************************************
+
+  FileName    [lpkAbcUtil.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    [Procedures working on decomposed functions.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkAbcUtil.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates the function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Fun_t * Lpk_FunAlloc( int nVars )
+{
+    Lpk_Fun_t * p;
+    p = (Lpk_Fun_t *)malloc( sizeof(Lpk_Fun_t) + sizeof(unsigned) * Kit_TruthWordNum(nVars) * 3 );
+    memset( p, 0, sizeof(Lpk_Fun_t) );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deletes the function]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_FunFree( Lpk_Fun_t * p )
+{
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the starting function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Fun_t * Lpk_FunCreate( Abc_Ntk_t * pNtk, Vec_Ptr_t * vLeaves, unsigned * pTruth, int nLutK, int AreaLim, int DelayLim )
+{
+    Lpk_Fun_t * p;
+    Abc_Obj_t * pNode;
+    int i;
+    p = Lpk_FunAlloc( Vec_PtrSize(vLeaves) );
+    p->Id = Vec_PtrSize(vLeaves);
+    p->vNodes = vLeaves;
+    p->nVars = Vec_PtrSize(vLeaves);
+    p->nLutK = nLutK;
+    p->nAreaLim = AreaLim;
+    p->nDelayLim = DelayLim;
+    p->uSupp = Kit_TruthSupport( pTruth, p->nVars );
+    Kit_TruthCopy( Lpk_FunTruth(p,0), pTruth, p->nVars );
+    Vec_PtrForEachEntry( vLeaves, pNode, i )
+    {
+        p->pFanins[i] = i;
+        p->pDelays[i] = pNode->Level;
+    }
+    Vec_PtrPush( p->vNodes, p );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the new function with the given truth table.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Fun_t * Lpk_FunDup( Lpk_Fun_t * p, unsigned * pTruth )
+{
+    Lpk_Fun_t * pNew;
+    pNew = Lpk_FunAlloc( p->nVars );
+    pNew->Id = Vec_PtrSize(p->vNodes);
+    pNew->vNodes = p->vNodes;
+    pNew->nVars = p->nVars;
+    pNew->nLutK = p->nLutK;
+    pNew->nAreaLim = p->nAreaLim;
+    pNew->nDelayLim = p->nDelayLim;
+    pNew->uSupp = Kit_TruthSupport( pTruth, p->nVars );
+    Kit_TruthCopy( Lpk_FunTruth(pNew,0), pTruth, p->nVars );
+    memcpy( pNew->pFanins, p->pFanins, 16 );
+    memcpy( pNew->pDelays, p->pDelays, 16 );
+    Vec_PtrPush( p->vNodes, pNew );
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Minimizes support of the function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_FunSuppMinimize( Lpk_Fun_t * p )
+{
+    int i, k, nVarsNew;
+    // compress the truth table
+    if ( p->uSupp == Kit_BitMask(p->nVars) )
+        return 0;
+    // invalidate support info
+    p->fSupports = 0;
+//Extra_PrintBinary( stdout, &p->uSupp, p->nVars ); printf( "\n" );
+    // minimize support
+    nVarsNew = Kit_WordCountOnes(p->uSupp);
+    Kit_TruthShrink( Lpk_FunTruth(p, 1), Lpk_FunTruth(p, 0), nVarsNew, p->nVars, p->uSupp, 1 );
+    k = 0;
+    Lpk_SuppForEachVar( p->uSupp, i )
+    {
+        p->pFanins[k] = p->pFanins[i];
+        p->pDelays[k] = p->pDelays[i];
+/*
+        if ( p->fSupports )
+        {
+            p->puSupps[2*k+0] = p->puSupps[2*i+0];
+            p->puSupps[2*k+1] = p->puSupps[2*i+1];
+        }
+*/
+        k++;
+    }
+    assert( k == nVarsNew );
+    p->nVars = k;
+    p->uSupp = Kit_BitMask(p->nVars);
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes cofactors w.r.t. each variable.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_FunComputeCofSupps( Lpk_Fun_t * p )
+{
+    unsigned * pTruth  = Lpk_FunTruth( p, 0 );
+    unsigned * pTruth0 = Lpk_FunTruth( p, 1 );
+    unsigned * pTruth1 = Lpk_FunTruth( p, 2 );
+    int Var;
+    assert( p->fSupports == 0 );
+//    Lpk_SuppForEachVar( p->uSupp, Var )
+    for ( Var = 0; Var < (int)p->nVars; Var++ )
+    {
+        Kit_TruthCofactor0New( pTruth0, pTruth, p->nVars, Var );
+        Kit_TruthCofactor1New( pTruth1, pTruth, p->nVars, Var );
+        p->puSupps[2*Var+0] = Kit_TruthSupport( pTruth0, p->nVars );
+        p->puSupps[2*Var+1] = Kit_TruthSupport( pTruth1, p->nVars );
+    }
+    p->fSupports = 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Get the delay of the bound set.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_SuppDelay( unsigned uSupp, char * pDelays )
+{
+    int Delay, Var;
+    Delay = 0;
+    Lpk_SuppForEachVar( uSupp, Var )
+        Delay = ABC_MAX( Delay, pDelays[Var] );
+    return Delay + 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts support into variables.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_SuppToVars( unsigned uBoundSet, char * pVars )
+{
+    int i, nVars = 0;
+    Lpk_SuppForEachVar( uBoundSet, i )
+        pVars[nVars++] = i;
+    return nVars;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkCore.c b/src/opt/lpk/lpkCore.c
new file mode 100644
index 00000000..8b8028e3
--- /dev/null
+++ b/src/opt/lpk/lpkCore.c
@@ -0,0 +1,659 @@
+/**CFile****************************************************************
+
+  FileName    [lpkCore.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkCore.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#include "lpkInt.h"
+#include "cloud.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares the mapping manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_IfManStart( Lpk_Man_t * p )
+{
+    If_Par_t * pPars;
+    assert( p->pIfMan == NULL );
+    // set defaults
+    pPars = ALLOC( If_Par_t, 1 );
+    memset( pPars, 0, sizeof(If_Par_t) );
+    // user-controlable paramters
+    pPars->nLutSize    =  p->pPars->nLutSize;
+    pPars->nCutsMax    = 16;
+    pPars->nFlowIters  =  0; // 1
+    pPars->nAreaIters  =  0; // 1 
+    pPars->DelayTarget = -1;
+    pPars->fPreprocess =  0;
+    pPars->fArea       =  1;
+    pPars->fFancy      =  0;
+    pPars->fExpRed     =  0; //
+    pPars->fLatchPaths =  0;
+    pPars->fSeqMap     =  0;
+    pPars->fVerbose    =  0;
+    // internal parameters
+    pPars->fTruth      =  1;
+    pPars->fUsePerm    =  0; 
+    pPars->nLatches    =  0;
+    pPars->pLutLib     =  NULL; // Abc_FrameReadLibLut();
+    pPars->pTimesArr   =  NULL; 
+    pPars->pTimesArr   =  NULL;   
+    pPars->fUseBdds    =  0;
+    pPars->fUseSops    =  0;
+    pPars->fUseCnfs    =  0;
+    pPars->fUseMv      =  0;
+    // start the mapping manager and set its parameters
+    p->pIfMan = If_ManStart( pPars );
+    If_ManSetupSetAll( p->pIfMan, 1000 );
+    p->pIfMan->pPars->pTimesArr = ALLOC( float, 32 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if at least one entry has changed.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_NodeHasChanged( Lpk_Man_t * p, int iNode )
+{
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pTemp;
+    int i;
+    vNodes = Vec_VecEntry( p->vVisited, iNode );
+    if ( Vec_PtrSize(vNodes) == 0 )
+        return 1;
+    Vec_PtrForEachEntry( vNodes, pTemp, i )
+    {
+        // check if the node has changed
+        pTemp = Abc_NtkObj( p->pNtk, (int)pTemp );
+        if ( pTemp == NULL )
+            return 1;
+        // check if the number of fanouts has changed
+//        if ( Abc_ObjFanoutNum(pTemp) != (int)Vec_PtrEntry(vNodes, i+1) )
+//            return 1;
+        i++;
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares the mapping manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_ExploreCut( Lpk_Man_t * p, Lpk_Cut_t * pCut, Kit_DsdNtk_t * pNtk )
+{
+    extern Abc_Obj_t * Abc_NodeFromIf_rec( Abc_Ntk_t * pNtkNew, If_Man_t * pIfMan, If_Obj_t * pIfObj, Vec_Int_t * vCover );
+    Kit_DsdObj_t * pRoot;
+    If_Obj_t * pDriver, * ppLeaves[16];
+    Abc_Obj_t * pLeaf, * pObjNew;
+    int nGain, i, clk;
+    int nNodesBef;
+//    int nOldShared;
+
+    // check special cases
+    pRoot = Kit_DsdNtkRoot( pNtk );
+    if ( pRoot->Type == KIT_DSD_CONST1 )
+    {
+        if ( Kit_DsdLitIsCompl(pNtk->Root) )
+            pObjNew = Abc_NtkCreateNodeConst0( p->pNtk );
+        else
+            pObjNew = Abc_NtkCreateNodeConst1( p->pNtk );
+        Abc_NtkUpdate( p->pObj, pObjNew, p->vLevels );
+        p->nGainTotal += pCut->nNodes - pCut->nNodesDup;
+        return 1;
+    }
+    if ( pRoot->Type == KIT_DSD_VAR )
+    {
+        pObjNew = Abc_NtkObj( p->pNtk, pCut->pLeaves[ Kit_DsdLit2Var(pRoot->pFans[0]) ] );
+        if ( Kit_DsdLitIsCompl(pNtk->Root) ^ Kit_DsdLitIsCompl(pRoot->pFans[0]) )
+            pObjNew = Abc_NtkCreateNodeInv( p->pNtk, pObjNew );
+        Abc_NtkUpdate( p->pObj, pObjNew, p->vLevels );
+        p->nGainTotal += pCut->nNodes - pCut->nNodesDup;
+        return 1;
+    }
+    assert( pRoot->Type == KIT_DSD_AND || pRoot->Type == KIT_DSD_XOR || pRoot->Type == KIT_DSD_PRIME );
+
+    // start the mapping manager
+    if ( p->pIfMan == NULL )
+        Lpk_IfManStart( p );
+
+    // prepare the mapping manager
+    If_ManRestart( p->pIfMan );
+    // create the PI variables
+    for ( i = 0; i < p->pPars->nVarsMax; i++ )
+        ppLeaves[i] = If_ManCreateCi( p->pIfMan );
+    // set the arrival times
+    Lpk_CutForEachLeaf( p->pNtk, pCut, pLeaf, i )
+        p->pIfMan->pPars->pTimesArr[i] = (float)pLeaf->Level;
+    // prepare the PI cuts
+    If_ManSetupCiCutSets( p->pIfMan );
+    // create the internal nodes
+    p->fCalledOnce = 0;
+    p->nCalledSRed = 0;
+    pDriver = Lpk_MapTree_rec( p, pNtk, ppLeaves, pNtk->Root, NULL );
+    if ( pDriver == NULL )
+        return 0;
+    // create the PO node
+    If_ManCreateCo( p->pIfMan, If_Regular(pDriver) );
+
+    // perform mapping
+    p->pIfMan->pPars->fAreaOnly = 1;
+clk = clock();
+    If_ManPerformMappingComb( p->pIfMan );
+p->timeMap += clock() - clk;
+
+    // compute the gain in area
+    nGain = pCut->nNodes - pCut->nNodesDup - (int)p->pIfMan->AreaGlo;
+    if ( p->pPars->fVeryVerbose )
+        printf( "       Mffc = %2d. Mapped = %2d. Gain = %3d. Depth increase = %d. SReds = %d.\n", 
+            pCut->nNodes - pCut->nNodesDup, (int)p->pIfMan->AreaGlo, nGain, (int)p->pIfMan->RequiredGlo - (int)p->pObj->Level, p->nCalledSRed );
+
+    // quit if there is no gain
+    if ( !(nGain > 0 || (p->pPars->fZeroCost && nGain == 0)) )
+        return 0;
+
+    // quit if depth increases too much
+    if ( (int)p->pIfMan->RequiredGlo > Abc_ObjRequiredLevel(p->pObj) )
+        return 0;
+
+    // perform replacement
+    p->nGainTotal += nGain;
+    p->nChanges++;
+    if ( p->nCalledSRed )
+        p->nBenefited++;
+
+    nNodesBef = Abc_NtkNodeNum(p->pNtk);
+    // prepare the mapping manager
+    If_ManCleanNodeCopy( p->pIfMan );
+    If_ManCleanCutData( p->pIfMan );
+    // set the PIs of the cut
+    Lpk_CutForEachLeaf( p->pNtk, pCut, pLeaf, i )
+        If_ObjSetCopy( If_ManCi(p->pIfMan, i), pLeaf );
+    // get the area of mapping
+    pObjNew = Abc_NodeFromIf_rec( p->pNtk, p->pIfMan, If_Regular(pDriver), p->vCover );
+    pObjNew->pData = Hop_NotCond( pObjNew->pData, If_IsComplement(pDriver) );
+    // perform replacement
+    Abc_NtkUpdate( p->pObj, pObjNew, p->vLevels );
+//printf( "%3d : %d-%d=%d(%d) \n", p->nChanges, nNodesBef, Abc_NtkNodeNum(p->pNtk), nNodesBef-Abc_NtkNodeNum(p->pNtk), nGain );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs resynthesis for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_ResynthesizeNode( Lpk_Man_t * p )
+{
+    static int Count = 0;
+    Kit_DsdNtk_t * pDsdNtk;
+    Lpk_Cut_t * pCut;
+    unsigned * pTruth;
+    int i, k, nSuppSize, nCutNodes, RetValue, clk;
+
+    // compute the cuts
+clk = clock();
+    if ( !Lpk_NodeCuts( p ) )
+    {
+p->timeCuts += clock() - clk;
+        return 0;
+    }
+p->timeCuts += clock() - clk;
+
+//return 0;
+
+    if ( p->pPars->fVeryVerbose )
+    printf( "Node %5d : Mffc size = %5d. Cuts = %5d.\n", p->pObj->Id, p->nMffc, p->nEvals );
+    // try the good cuts
+    p->nCutsTotal  += p->nCuts;
+    p->nCutsUseful += p->nEvals;
+    for ( i = 0; i < p->nEvals; i++ )
+    {
+        // get the cut
+        pCut = p->pCuts + p->pEvals[i];
+        if ( p->pPars->fFirst && i == 1 )
+            break;
+
+        // skip bad cuts        
+//        printf( "Mffc size = %d.  ", Abc_NodeMffcLabel(p->pObj) );
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+            Abc_NtkObj(p->pNtk, pCut->pLeaves[k])->vFanouts.nSize++;
+        nCutNodes = Abc_NodeMffcLabel(p->pObj);
+//        printf( "Mffc with cut = %d.  ", nCutNodes );
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+            Abc_NtkObj(p->pNtk, pCut->pLeaves[k])->vFanouts.nSize--;
+//        printf( "Mffc cut = %d.  ", (int)pCut->nNodes - (int)pCut->nNodesDup );
+//        printf( "\n" );
+        if ( nCutNodes != (int)pCut->nNodes - (int)pCut->nNodesDup )
+            continue;
+
+        // compute the truth table
+clk = clock();
+        pTruth = Lpk_CutTruth( p, pCut, 0 );
+        nSuppSize = Extra_TruthSupportSize(pTruth, pCut->nLeaves);
+p->timeTruth += clock() - clk;
+
+        pDsdNtk = Kit_DsdDecompose( pTruth, pCut->nLeaves ); 
+//        Kit_DsdVerify( pDsdNtk, pTruth, pCut->nLeaves ); 
+        // skip 16-input non-DSD because ISOP will not work
+        if ( Kit_DsdNtkRoot(pDsdNtk)->nFans == 16 ) 
+        {
+            Kit_DsdNtkFree( pDsdNtk );
+            continue;
+        }
+
+        // if DSD has nodes that require splitting to fit them into LUTs
+        // we can skip those cuts that cannot lead to improvement
+        // (a full DSD network requires  V = Nmin * (K-1) + 1 for improvement)
+        if ( Kit_DsdNonDsdSizeMax(pDsdNtk) > p->pPars->nLutSize && 
+             nSuppSize >= ((int)pCut->nNodes - (int)pCut->nNodesDup - 1) * (p->pPars->nLutSize - 1) + 1 )
+        {
+            Kit_DsdNtkFree( pDsdNtk );
+            continue;
+        }
+
+        if ( p->pPars->fVeryVerbose )
+        {
+//            char * pFileName;
+            printf( "  C%02d: L= %2d/%2d  V= %2d/%d  N= %d  W= %4.2f  ", 
+                i, pCut->nLeaves, nSuppSize, pCut->nNodes, pCut->nNodesDup, pCut->nLuts, pCut->Weight );
+            Kit_DsdPrint( stdout, pDsdNtk );
+            Kit_DsdPrintFromTruth( pTruth, pCut->nLeaves );
+//            pFileName = Kit_TruthDumpToFile( pTruth, pCut->nLeaves, Count++ );
+//            printf( "Saved truth table in file \"%s\".\n", pFileName );
+        }
+
+        // update the network
+clk = clock();
+        RetValue = Lpk_ExploreCut( p, pCut, pDsdNtk );
+p->timeEval += clock() - clk;
+        Kit_DsdNtkFree( pDsdNtk );
+        if ( RetValue )
+            break;
+    }
+    return 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes supports of the cofactors of the function.]
+
+  Description [This procedure should be called after Lpk_CutTruth(p,pCut,0)]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_ComputeSupports( Lpk_Man_t * p, Lpk_Cut_t * pCut, unsigned * pTruth )
+{
+    unsigned * pTruthInv;
+    int RetValue1, RetValue2;
+    pTruthInv = Lpk_CutTruth( p, pCut, 1 );
+    RetValue1 = Kit_CreateCloudFromTruth( p->pDsdMan->dd, pTruth, pCut->nLeaves, p->vBddDir );
+    RetValue2 = Kit_CreateCloudFromTruth( p->pDsdMan->dd, pTruthInv, pCut->nLeaves, p->vBddInv );
+    if ( RetValue1 && RetValue2 )
+        Kit_TruthCofSupports( p->vBddDir, p->vBddInv, pCut->nLeaves, p->vMemory, p->puSupps ); 
+    else
+        p->puSupps[0] = p->puSupps[1] = 0;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Performs resynthesis for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_ResynthesizeNodeNew( Lpk_Man_t * p )
+{
+    static int Count = 0;
+    Abc_Obj_t * pObjNew, * pLeaf;
+    Lpk_Cut_t * pCut;
+    unsigned * pTruth;
+    int nNodesBef, nNodesAft, nCutNodes;
+    int i, k, clk;
+    int Required = Abc_ObjRequiredLevel(p->pObj);
+//    CloudNode * pFun2;//, * pFun1;
+
+    // compute the cuts
+clk = clock();
+    if ( !Lpk_NodeCuts( p ) )
+    {
+p->timeCuts += clock() - clk;
+        return 0;
+    }
+p->timeCuts += clock() - clk;
+
+    if ( p->pPars->fVeryVerbose )
+        printf( "Node %5d : Mffc size = %5d. Cuts = %5d.  Level = %2d. Req = %2d.\n", 
+            p->pObj->Id, p->nMffc, p->nEvals, p->pObj->Level, Required );
+    // try the good cuts
+    p->nCutsTotal  += p->nCuts;
+    p->nCutsUseful += p->nEvals;
+    for ( i = 0; i < p->nEvals; i++ )
+    {
+        // get the cut
+        pCut = p->pCuts + p->pEvals[i];
+        if ( p->pPars->fFirst && i == 1 )
+            break;
+//        if ( pCut->Weight < 1.05 )
+//            continue;
+
+        // skip bad cuts        
+//        printf( "Mffc size = %d.  ", Abc_NodeMffcLabel(p->pObj) );
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+            Abc_NtkObj(p->pNtk, pCut->pLeaves[k])->vFanouts.nSize++;
+        nCutNodes = Abc_NodeMffcLabel(p->pObj);
+//        printf( "Mffc with cut = %d.  ", nCutNodes );
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+            Abc_NtkObj(p->pNtk, pCut->pLeaves[k])->vFanouts.nSize--;
+//        printf( "Mffc cut = %d.  ", (int)pCut->nNodes - (int)pCut->nNodesDup );
+//        printf( "\n" );
+        if ( nCutNodes != (int)pCut->nNodes - (int)pCut->nNodesDup )
+            continue;
+
+        // collect nodes into the array
+        Vec_PtrClear( p->vLeaves );
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+            Vec_PtrPush( p->vLeaves, Abc_NtkObj(p->pNtk, pCut->pLeaves[k]) );
+
+        // compute the truth table
+clk = clock();
+        pTruth = Lpk_CutTruth( p, pCut, 0 );
+p->timeTruth += clock() - clk;
+clk = clock();
+        Lpk_ComputeSupports( p, pCut, pTruth );        
+p->timeSupps += clock() - clk;
+//clk = clock();
+//        pFun1 = Lpk_CutTruthBdd( p, pCut );
+//p->timeTruth2 += clock() - clk;
+/*
+clk = clock();
+        Cloud_Restart( p->pDsdMan->dd );
+        pFun2 = Kit_TruthToCloud( p->pDsdMan->dd, pTruth, pCut->nLeaves );
+        RetValue = Kit_CreateCloud( p->pDsdMan->dd, pFun2, p->vBddNodes );
+p->timeTruth3 += clock() - clk;
+*/
+//        if ( pFun1 != pFun2 )
+//            printf( "Truth tables do not agree!\n" );
+//        else
+//            printf( "Fine!\n" );
+
+        if ( p->pPars->fVeryVerbose )
+        {
+//            char * pFileName;
+            int nSuppSize = Extra_TruthSupportSize( pTruth, pCut->nLeaves );
+            printf( "  C%02d: L= %2d/%2d  V= %2d/%d  N= %d  W= %4.2f  ", 
+                i, pCut->nLeaves, nSuppSize, pCut->nNodes, pCut->nNodesDup, pCut->nLuts, pCut->Weight );
+            Vec_PtrForEachEntry( p->vLeaves, pLeaf, k )
+                printf( "%c=%d ", 'a'+k, Abc_ObjLevel(pLeaf) );
+            printf( "\n" );
+            Kit_DsdPrintFromTruth( pTruth, pCut->nLeaves );
+//            pFileName = Kit_TruthDumpToFile( pTruth, pCut->nLeaves, Count++ );
+//            printf( "Saved truth table in file \"%s\".\n", pFileName );
+        }
+        if ( p->pObj->Id == 33 && i == 0 )
+        {
+            int x = 0;
+        }
+
+        // update the network
+        nNodesBef = Abc_NtkNodeNum(p->pNtk);
+clk = clock();
+        pObjNew = Lpk_Decompose( p, p->pNtk, p->vLeaves, pTruth, p->puSupps, p->pPars->nLutSize,
+            (int)pCut->nNodes - (int)pCut->nNodesDup - 1 + (int)(p->pPars->fZeroCost > 0), Required );
+p->timeEval += clock() - clk;
+        nNodesAft = Abc_NtkNodeNum(p->pNtk);
+
+        // perform replacement
+        if ( pObjNew )
+        {
+            int nGain = (int)pCut->nNodes - (int)pCut->nNodesDup - (nNodesAft - nNodesBef);
+            assert( nGain >= 1 - p->pPars->fZeroCost );
+            assert( Abc_ObjLevel(pObjNew) <= Required );
+/*
+            if ( nGain <= 0 )
+            {
+                int x = 0;
+            }
+            if ( Abc_ObjLevel(pObjNew) > Required )
+            {
+                int x = 0;
+            }
+*/
+            p->nGainTotal += nGain;
+            p->nChanges++;
+            if ( p->pPars->fVeryVerbose )
+                printf( "Performed resynthesis: Gain = %2d. Level = %2d. Req = %2d.\n", nGain, Abc_ObjLevel(pObjNew), Required );
+            Abc_NtkUpdate( p->pObj, pObjNew, p->vLevels );
+//printf( "%3d : %d-%d=%d(%d) \n", p->nChanges, nNodesBef, Abc_NtkNodeNum(p->pNtk), nNodesBef-Abc_NtkNodeNum(p->pNtk), nGain );
+            break;
+        }
+    }
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs resynthesis for one network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_Resynthesize( Abc_Ntk_t * pNtk, Lpk_Par_t * pPars )
+{
+    ProgressBar * pProgress;
+    Lpk_Man_t * p;
+    Abc_Obj_t * pObj;
+    double Delta;
+    int i, Iter, nNodes, nNodesPrev, clk = clock();
+    assert( Abc_NtkIsLogic(pNtk) );
+
+    // sweep dangling nodes as a preprocessing step
+    Abc_NtkSweep( pNtk, 0 );
+
+    // get the number of inputs
+    pPars->nLutSize = Abc_NtkGetFaninMax( pNtk );
+    // adjust the number of crossbars based on LUT size
+    if ( pPars->nVarsShared > pPars->nLutSize - 2 )
+        pPars->nVarsShared = pPars->nLutSize - 2;
+    // get the max number of LUTs tried
+    pPars->nVarsMax = pPars->nLutsMax * (pPars->nLutSize - 1) + 1; // V = N * (K-1) + 1
+    while ( pPars->nVarsMax > 16 )
+    {
+        pPars->nLutsMax--;
+        pPars->nVarsMax = pPars->nLutsMax * (pPars->nLutSize - 1) + 1;
+
+    }
+    if ( pPars->fVerbose )
+    {
+        printf( "Resynthesis for %d %d-LUTs with %d non-MFFC LUTs, %d crossbars, and %d-input cuts.\n",
+            pPars->nLutsMax, pPars->nLutSize, pPars->nLutsOver, pPars->nVarsShared, pPars->nVarsMax );
+    }
+ 
+
+    // convert into the AIG
+    if ( !Abc_NtkToAig(pNtk) )
+    {
+        fprintf( stdout, "Converting to BDD has failed.\n" );
+        return 0;
+    }
+    assert( Abc_NtkHasAig(pNtk) );
+
+    // set the number of levels
+    Abc_NtkLevel( pNtk );
+    Abc_NtkStartReverseLevels( pNtk, pPars->nGrowthLevel );
+
+    // start the manager
+    p = Lpk_ManStart( pPars );
+    p->pNtk = pNtk;
+    p->nNodesTotal = Abc_NtkNodeNum(pNtk);
+    p->vLevels = Vec_VecStart( pNtk->LevelMax ); 
+    if ( p->pPars->fSatur )
+        p->vVisited = Vec_VecStart( 0 );
+    if ( pPars->fVerbose )
+    {
+        p->nTotalNets = Abc_NtkGetTotalFanins(pNtk);
+        p->nTotalNodes = Abc_NtkNodeNum(pNtk);
+    }
+
+    // iterate over the network
+    nNodesPrev = p->nNodesTotal;
+    for ( Iter = 1; ; Iter++ )
+    {
+        // expand storage for changed nodes
+        if ( p->pPars->fSatur )
+            Vec_VecExpand( p->vVisited, Abc_NtkObjNumMax(pNtk) + 1 );
+
+        // consider all nodes
+        nNodes = Abc_NtkObjNumMax(pNtk);
+        if ( !pPars->fVeryVerbose )
+            pProgress = Extra_ProgressBarStart( stdout, nNodes );
+        Abc_NtkForEachNode( pNtk, pObj, i )
+        {
+            // skip all except the final node
+            if ( pPars->fFirst )
+            {
+                if ( !Abc_ObjIsCo(Abc_ObjFanout0(pObj)) )
+                    continue;
+            }
+            if ( i >= nNodes )
+                break;
+            if ( !pPars->fVeryVerbose )
+                Extra_ProgressBarUpdate( pProgress, i, NULL );
+            // skip the nodes that did not change
+            if ( p->pPars->fSatur && !Lpk_NodeHasChanged(p, pObj->Id) )
+                continue;
+            // resynthesize
+            p->pObj = pObj;
+            if ( p->pPars->fOldAlgo )
+                Lpk_ResynthesizeNode( p );
+            else
+                Lpk_ResynthesizeNodeNew( p );
+        }
+        if ( !pPars->fVeryVerbose )
+            Extra_ProgressBarStop( pProgress );
+
+        // check the increase
+        Delta = 100.00 * (nNodesPrev - Abc_NtkNodeNum(pNtk)) / p->nNodesTotal;
+        if ( Delta < 0.05 )
+            break;
+        nNodesPrev = Abc_NtkNodeNum(pNtk);
+        if ( !p->pPars->fSatur )
+            break;
+
+        if ( pPars->fFirst )
+            break;
+    }
+    Abc_NtkStopReverseLevels( pNtk );
+
+    if ( pPars->fVerbose )
+    {
+//        Cloud_PrintInfo( p->pDsdMan->dd );
+        p->nTotalNets2 = Abc_NtkGetTotalFanins(pNtk);
+        p->nTotalNodes2 = Abc_NtkNodeNum(pNtk);
+        printf( "Node gain = %5d. (%.2f %%)  ", 
+            p->nTotalNodes-p->nTotalNodes2, 100.0*(p->nTotalNodes-p->nTotalNodes2)/p->nTotalNodes );
+        printf( "Edge gain = %5d. (%.2f %%)  ", 
+            p->nTotalNets-p->nTotalNets2, 100.0*(p->nTotalNets-p->nTotalNets2)/p->nTotalNets );
+        printf( "Muxes = %4d. Dsds = %4d.", p->nMuxes, p->nDsds );
+        printf( "\n" );
+        printf( "Nodes = %5d (%3d)  Cuts = %5d (%4d)  Changes = %5d  Iter = %2d  Benefit = %d.\n", 
+            p->nNodesTotal, p->nNodesOver, p->nCutsTotal, p->nCutsUseful, p->nChanges, Iter, p->nBenefited );
+
+        printf( "Non-DSD:" );
+        for ( i = 3; i <= pPars->nVarsMax; i++ )
+            if ( p->nBlocks[i] )
+                printf( " %d=%d", i, p->nBlocks[i] );
+        printf( "\n" );
+
+        p->timeTotal = clock() - clk;
+        p->timeEval  = p->timeEval  - p->timeMap;
+        p->timeOther = p->timeTotal - p->timeCuts - p->timeTruth - p->timeEval - p->timeMap;
+        PRTP( "Cuts  ", p->timeCuts,  p->timeTotal );
+        PRTP( "Truth ", p->timeTruth, p->timeTotal );
+        PRTP( "CSupps", p->timeSupps, p->timeTotal );
+        PRTP( "Eval  ", p->timeEval,  p->timeTotal );
+        PRTP( " MuxAn", p->timeEvalMuxAn, p->timeEval );
+        PRTP( " MuxSp", p->timeEvalMuxSp, p->timeEval );
+        PRTP( " DsdAn", p->timeEvalDsdAn, p->timeEval );
+        PRTP( " DsdSp", p->timeEvalDsdSp, p->timeEval );
+        PRTP( " Other", p->timeEval-p->timeEvalMuxAn-p->timeEvalMuxSp-p->timeEvalDsdAn-p->timeEvalDsdSp, p->timeEval );
+        PRTP( "Map   ", p->timeMap,   p->timeTotal );
+        PRTP( "Other ", p->timeOther, p->timeTotal );
+        PRTP( "TOTAL ", p->timeTotal, p->timeTotal );
+    }
+
+    Lpk_ManStop( p );
+    // check the resulting network
+    if ( !Abc_NtkCheck( pNtk ) )
+    {
+        printf( "Lpk_Resynthesize: The network check has failed.\n" );
+        return 0;
+    }
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkCut.c b/src/opt/lpk/lpkCut.c
new file mode 100644
index 00000000..b2a743bd
--- /dev/null
+++ b/src/opt/lpk/lpkCut.c
@@ -0,0 +1,683 @@
+/**CFile****************************************************************
+
+  FileName    [lpkCut.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkCut.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+#include "cloud.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth table of one cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+CloudNode * Lpk_CutTruthBdd_rec( CloudManager * dd, Hop_Man_t * pMan, Hop_Obj_t * pObj, int nVars )
+{
+    CloudNode * pTruth, * pTruth0, * pTruth1;
+    assert( !Hop_IsComplement(pObj) );
+    if ( pObj->pData )
+    {
+        assert( ((unsigned)pObj->pData) & 0xffff0000 );
+        return pObj->pData;
+    }
+    // get the plan for a new truth table
+    if ( Hop_ObjIsConst1(pObj) )
+        pTruth = dd->one;
+    else
+    {
+        assert( Hop_ObjIsAnd(pObj) );
+        // compute the truth tables of the fanins
+        pTruth0 = Lpk_CutTruthBdd_rec( dd, pMan, Hop_ObjFanin0(pObj), nVars );
+        pTruth1 = Lpk_CutTruthBdd_rec( dd, pMan, Hop_ObjFanin1(pObj), nVars );
+        pTruth0 = Cloud_NotCond( pTruth0, Hop_ObjFaninC0(pObj) );
+        pTruth1 = Cloud_NotCond( pTruth1, Hop_ObjFaninC1(pObj) );
+        // creat the truth table of the node
+        pTruth = Cloud_bddAnd( dd, pTruth0, pTruth1 );
+    }
+    pObj->pData = pTruth;
+    return pTruth;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies that the factoring is correct.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+CloudNode * Lpk_CutTruthBdd( Lpk_Man_t * p, Lpk_Cut_t * pCut )
+{
+    CloudManager * dd = p->pDsdMan->dd;
+    Hop_Man_t * pManHop = p->pNtk->pManFunc;
+    Hop_Obj_t * pObjHop;
+    Abc_Obj_t * pObj, * pFanin;
+    CloudNode * pTruth;
+    int i, k, iCount = 0;
+
+//    return NULL;
+//    Lpk_NodePrintCut( p, pCut );
+    // initialize the leaves
+    Lpk_CutForEachLeaf( p->pNtk, pCut, pObj, i )
+        pObj->pCopy = (Abc_Obj_t *)dd->vars[pCut->nLeaves-1-i];
+
+    // construct truth table in the topological order
+    Lpk_CutForEachNodeReverse( p->pNtk, pCut, pObj, i )
+    {
+        // get the local AIG
+        pObjHop = Hop_Regular(pObj->pData);
+        // clean the data field of the nodes in the AIG subgraph
+        Hop_ObjCleanData_rec( pObjHop );
+        // set the initial truth tables at the fanins
+        Abc_ObjForEachFanin( pObj, pFanin, k )
+        {
+            assert( ((unsigned)pFanin->pCopy) & 0xffff0000 );
+            Hop_ManPi( pManHop, k )->pData = pFanin->pCopy;
+        }
+        // compute the truth table of internal nodes
+        pTruth = Lpk_CutTruthBdd_rec( dd, pManHop, pObjHop, pCut->nLeaves );
+        if ( Hop_IsComplement(pObj->pData) )
+            pTruth = Cloud_Not(pTruth);
+        // set the truth table at the node
+        pObj->pCopy = (Abc_Obj_t *)pTruth;
+        
+    }
+
+//    Cloud_bddPrint( dd, pTruth );
+//    printf( "Bdd size = %d. Total nodes = %d.\n", Cloud_DagSize( dd, pTruth ), dd->nNodesCur-dd->nVars-1 );
+    return pTruth;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth table of one cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned * Lpk_CutTruth_rec( Hop_Man_t * pMan, Hop_Obj_t * pObj, int nVars, Vec_Ptr_t * vTtNodes, int * piCount )
+{
+    unsigned * pTruth, * pTruth0, * pTruth1;
+    assert( !Hop_IsComplement(pObj) );
+    if ( pObj->pData )
+    {
+        assert( ((unsigned)pObj->pData) & 0xffff0000 );
+        return pObj->pData;
+    }
+    // get the plan for a new truth table
+    pTruth = Vec_PtrEntry( vTtNodes, (*piCount)++ );
+    if ( Hop_ObjIsConst1(pObj) )
+        Kit_TruthFill( pTruth, nVars );
+    else
+    {
+        assert( Hop_ObjIsAnd(pObj) );
+        // compute the truth tables of the fanins
+        pTruth0 = Lpk_CutTruth_rec( pMan, Hop_ObjFanin0(pObj), nVars, vTtNodes, piCount );
+        pTruth1 = Lpk_CutTruth_rec( pMan, Hop_ObjFanin1(pObj), nVars, vTtNodes, piCount );
+        // creat the truth table of the node
+        Kit_TruthAndPhase( pTruth, pTruth0, pTruth1, nVars, Hop_ObjFaninC0(pObj), Hop_ObjFaninC1(pObj) );
+    }
+    pObj->pData = pTruth;
+    return pTruth;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the truth able of one cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned * Lpk_CutTruth( Lpk_Man_t * p, Lpk_Cut_t * pCut, int fInv )
+{
+    Hop_Man_t * pManHop = p->pNtk->pManFunc;
+    Hop_Obj_t * pObjHop;
+    Abc_Obj_t * pObj, * pFanin;
+    unsigned * pTruth;
+    int i, k, iCount = 0;
+//    Lpk_NodePrintCut( p, pCut );
+    assert( pCut->nNodes > 0 );
+
+    // initialize the leaves
+    Lpk_CutForEachLeaf( p->pNtk, pCut, pObj, i )
+        pObj->pCopy = Vec_PtrEntry( p->vTtElems, fInv? pCut->nLeaves-1-i : i );
+
+    // construct truth table in the topological order
+    Lpk_CutForEachNodeReverse( p->pNtk, pCut, pObj, i )
+    {
+        // get the local AIG
+        pObjHop = Hop_Regular(pObj->pData);
+        // clean the data field of the nodes in the AIG subgraph
+        Hop_ObjCleanData_rec( pObjHop );
+        // set the initial truth tables at the fanins
+        Abc_ObjForEachFanin( pObj, pFanin, k )
+        {
+            assert( ((unsigned)pFanin->pCopy) & 0xffff0000 );
+            Hop_ManPi( pManHop, k )->pData = pFanin->pCopy;
+        }
+        // compute the truth table of internal nodes
+        pTruth = Lpk_CutTruth_rec( pManHop, pObjHop, pCut->nLeaves, p->vTtNodes, &iCount );
+        if ( Hop_IsComplement(pObj->pData) )
+            Kit_TruthNot( pTruth, pTruth, pCut->nLeaves );
+        // set the truth table at the node
+        pObj->pCopy = (Abc_Obj_t *)pTruth;
+    }
+
+    // make sure direct truth table is stored elsewhere (assuming the first call for direct truth!!!)
+    if ( fInv == 0 )
+    {
+        pTruth = Vec_PtrEntry( p->vTtNodes, iCount++ );
+        Kit_TruthCopy( pTruth, (unsigned *)pObj->pCopy, pCut->nLeaves );
+    }
+    assert( iCount <= Vec_PtrSize(p->vTtNodes) );
+    return pTruth;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if at least one entry has changed.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_NodeRecordImpact( Lpk_Man_t * p )
+{
+    Lpk_Cut_t * pCut;
+    Vec_Ptr_t * vNodes = Vec_VecEntry( p->vVisited, p->pObj->Id );
+    Abc_Obj_t * pNode;
+    int i, k;
+    // collect the nodes that impact the given node
+    Vec_PtrClear( vNodes );
+    for ( i = 0; i < p->nCuts; i++ )
+    {
+        pCut = p->pCuts + i;
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+        {
+            pNode = Abc_NtkObj( p->pNtk, pCut->pLeaves[k] );
+            if ( pNode->fMarkC )
+                continue;
+            pNode->fMarkC = 1;
+            Vec_PtrPush( vNodes, (void *)pNode->Id );
+            Vec_PtrPush( vNodes, (void *)Abc_ObjFanoutNum(pNode) );
+        }
+    }
+    // clear the marks
+    Vec_PtrForEachEntry( vNodes, pNode, i )
+    {
+        pNode = Abc_NtkObj( p->pNtk, (int)pNode );
+        pNode->fMarkC = 0;
+        i++;
+    }
+//printf( "%d ", Vec_PtrSize(vNodes) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the cut has structural DSD.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_NodeCutsCheckDsd( Lpk_Man_t * p, Lpk_Cut_t * pCut )
+{
+    Abc_Obj_t * pObj, * pFanin;
+    int i, k, nCands, fLeavesOnly, RetValue;
+    assert( pCut->nLeaves > 0 );
+    // clear ref counters
+    memset( p->pRefs, 0, sizeof(int) * pCut->nLeaves );
+    // mark cut leaves
+    Lpk_CutForEachLeaf( p->pNtk, pCut, pObj, i )
+    {
+        assert( pObj->fMarkA == 0 );
+        pObj->fMarkA = 1;
+        pObj->pCopy = (void *)i;
+    }
+    // ref leaves pointed from the internal nodes
+    nCands = 0;
+    Lpk_CutForEachNode( p->pNtk, pCut, pObj, i )
+    {
+        fLeavesOnly = 1;
+        Abc_ObjForEachFanin( pObj, pFanin, k )
+            if ( pFanin->fMarkA )
+                p->pRefs[(int)pFanin->pCopy]++;
+            else
+                fLeavesOnly = 0;
+        if ( fLeavesOnly )
+            p->pCands[nCands++] = pObj->Id;
+    }
+    // look at the nodes that only point to the leaves
+    RetValue = 0;
+    for ( i = 0; i < nCands; i++ )
+    {
+        pObj = Abc_NtkObj( p->pNtk, p->pCands[i] );
+        Abc_ObjForEachFanin( pObj, pFanin, k )
+        {
+            assert( pFanin->fMarkA == 1 );
+            if ( p->pRefs[(int)pFanin->pCopy] > 1 )
+                break;
+        }
+        if ( k == Abc_ObjFaninNum(pObj) )
+        {
+            RetValue = 1;
+            break;
+        }
+    }
+    // unmark cut leaves
+    Lpk_CutForEachLeaf( p->pNtk, pCut, pObj, i )
+        pObj->fMarkA = 0;
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if pDom is contained in pCut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Lpk_NodeCutsOneDominance( Lpk_Cut_t * pDom, Lpk_Cut_t * pCut )
+{
+    int i, k;
+    for ( i = 0; i < (int)pDom->nLeaves; i++ )
+    {
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+            if ( pDom->pLeaves[i] == pCut->pLeaves[k] )
+                break;
+        if ( k == (int)pCut->nLeaves ) // node i in pDom is not contained in pCut
+            return 0;
+    }
+    // every node in pDom is contained in pCut
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Check if the cut exists.]
+
+  Description [Returns 1 if the cut exists.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_NodeCutsOneFilter( Lpk_Cut_t * pCuts, int nCuts, Lpk_Cut_t * pCutNew )
+{
+    Lpk_Cut_t * pCut;
+    int i, k;
+    assert( pCutNew->uSign[0] || pCutNew->uSign[1] );
+    // try to find the cut
+    for ( i = 0; i < nCuts; i++ )
+    {
+        pCut = pCuts + i;
+        if ( pCut->nLeaves == 0 )
+            continue;
+        if ( pCut->nLeaves == pCutNew->nLeaves )
+        {
+            if ( pCut->uSign[0] == pCutNew->uSign[0] && pCut->uSign[1] == pCutNew->uSign[1] )
+            {
+                for ( k = 0; k < (int)pCutNew->nLeaves; k++ )
+                    if ( pCut->pLeaves[k] != pCutNew->pLeaves[k] )
+                        break;
+                if ( k == (int)pCutNew->nLeaves )
+                    return 1;
+            }
+            continue;
+        }
+        if ( pCut->nLeaves < pCutNew->nLeaves )
+        {
+            // skip the non-contained cuts
+            if ( (pCut->uSign[0] & pCutNew->uSign[0]) != pCut->uSign[0] )
+                continue;
+            if ( (pCut->uSign[1] & pCutNew->uSign[1]) != pCut->uSign[1] )
+                continue;
+            // check containment seriously
+            if ( Lpk_NodeCutsOneDominance( pCut, pCutNew ) )
+                return 1;
+            continue;
+        }
+        // check potential containment of other cut
+
+        // skip the non-contained cuts
+        if ( (pCut->uSign[0] & pCutNew->uSign[0]) != pCutNew->uSign[0] )
+            continue;
+        if ( (pCut->uSign[1] & pCutNew->uSign[1]) != pCutNew->uSign[1] )
+            continue;
+        // check containment seriously
+        if ( Lpk_NodeCutsOneDominance( pCutNew, pCut ) )
+            pCut->nLeaves = 0; // removed
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the given cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_NodePrintCut( Lpk_Man_t * p, Lpk_Cut_t * pCut, int fLeavesOnly )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    if ( !fLeavesOnly )
+        printf( "LEAVES:\n" );
+    Lpk_CutForEachLeaf( p->pNtk, pCut, pObj, i )
+        printf( "%d,", pObj->Id );
+    if ( !fLeavesOnly )
+    {
+        printf( "\nNODES:\n" );
+        Lpk_CutForEachNode( p->pNtk, pCut, pObj, i )
+        {
+            printf( "%d,", pObj->Id );
+            assert( Abc_ObjIsNode(pObj) );
+        }
+        printf( "\n" );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Set the cut signature.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_NodeCutSignature( Lpk_Cut_t * pCut )
+{
+    unsigned i;
+    pCut->uSign[0] = pCut->uSign[1] = 0;
+    for ( i = 0; i < pCut->nLeaves; i++ )
+    {
+        pCut->uSign[(pCut->pLeaves[i] & 32) > 0] |= (1 << (pCut->pLeaves[i] & 31));
+        if ( i != pCut->nLeaves - 1 )
+            assert( pCut->pLeaves[i] < pCut->pLeaves[i+1] );
+    }
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the set of all cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_NodeCutsOne( Lpk_Man_t * p, Lpk_Cut_t * pCut, int Node )
+{
+    Lpk_Cut_t * pCutNew;
+    Abc_Obj_t * pObj, * pFanin;
+    int i, k, j, nLeavesNew;
+/*
+    printf( "Exploring cut " );
+    Lpk_NodePrintCut( p, pCut, 1 );
+    printf( "with node %d\n", Node );
+*/
+    // check if the cut can stand adding one more internal node
+    if ( pCut->nNodes == LPK_SIZE_MAX )
+        return;
+
+    // if the node is a PI, quit
+    pObj = Abc_NtkObj( p->pNtk, Node );
+    if ( Abc_ObjIsCi(pObj) )
+        return;
+    assert( Abc_ObjIsNode(pObj) );
+    assert( Abc_ObjFaninNum(pObj) <= p->pPars->nLutSize );
+
+    // if the node is not in the MFFC, check the limit
+    if ( !Abc_NodeIsTravIdCurrent(pObj) )
+    {
+        if ( (int)pCut->nNodesDup == p->pPars->nLutsOver )
+            return;
+        assert( (int)pCut->nNodesDup < p->pPars->nLutsOver );
+    }
+
+    // check the possibility of adding this node using the signature
+    nLeavesNew = pCut->nLeaves - 1;
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+    {
+        if ( (pCut->uSign[(pFanin->Id & 32) > 0] & (1 << (pFanin->Id & 31))) )
+            continue;
+        if ( ++nLeavesNew > p->pPars->nVarsMax )
+            return;
+    }
+
+    // initialize the set of leaves to the nodes in the cut
+    assert( p->nCuts < LPK_CUTS_MAX );
+    pCutNew = p->pCuts + p->nCuts;
+    pCutNew->nLeaves = 0;
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+        if ( pCut->pLeaves[i] != Node )
+            pCutNew->pLeaves[pCutNew->nLeaves++] = pCut->pLeaves[i];
+
+    // add new nodes
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+    {
+        // find the place where this node belongs
+        for ( k = 0; k < (int)pCutNew->nLeaves; k++ )
+            if ( pCutNew->pLeaves[k] >= pFanin->Id )
+                break;
+        if ( k < (int)pCutNew->nLeaves && pCutNew->pLeaves[k] == pFanin->Id )
+            continue;
+        // check if there is room
+        if ( (int)pCutNew->nLeaves == p->pPars->nVarsMax )
+            return;
+        // move all the nodes
+        for ( j = pCutNew->nLeaves; j > k; j-- )
+            pCutNew->pLeaves[j] = pCutNew->pLeaves[j-1];
+        pCutNew->pLeaves[k] = pFanin->Id;
+        pCutNew->nLeaves++;
+        assert( pCutNew->nLeaves <= LPK_SIZE_MAX );
+
+    }
+    // skip the contained cuts
+    Lpk_NodeCutSignature( pCutNew );
+    if ( Lpk_NodeCutsOneFilter( p->pCuts, p->nCuts, pCutNew ) )
+        return;
+
+    // update the set of internal nodes
+    assert( pCut->nNodes < LPK_SIZE_MAX );
+    memcpy( pCutNew->pNodes, pCut->pNodes, pCut->nNodes * sizeof(int) );
+    pCutNew->nNodes = pCut->nNodes;
+    pCutNew->nNodesDup = pCut->nNodesDup;
+
+    // check if the node is already there
+    // if so, move the node to be the last
+    for ( i = 0; i < (int)pCutNew->nNodes; i++ )
+        if ( pCutNew->pNodes[i] == Node )
+        {
+            for ( k = i; k < (int)pCutNew->nNodes - 1; k++ )
+                pCutNew->pNodes[k] = pCutNew->pNodes[k+1];
+            pCutNew->pNodes[k] = Node;
+            break;
+        }
+    if ( i == (int)pCutNew->nNodes ) // new node
+    {
+        pCutNew->pNodes[ pCutNew->nNodes++ ] = Node;
+        pCutNew->nNodesDup += !Abc_NodeIsTravIdCurrent(pObj);
+    }
+    // the number of nodes does not exceed MFFC plus duplications
+    assert( pCutNew->nNodes <= p->nMffc + pCutNew->nNodesDup );
+    // add the cut to storage
+    assert( p->nCuts < LPK_CUTS_MAX );
+    p->nCuts++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the set of all cuts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_NodeCuts( Lpk_Man_t * p )
+{
+    Lpk_Cut_t * pCut, * pCut2;
+    int i, k, Temp, nMffc, fChanges;
+
+    // mark the MFFC of the node with the current trav ID
+    nMffc = p->nMffc = Abc_NodeMffcLabel( p->pObj );
+    assert( nMffc > 0 );
+    if ( nMffc == 1 )
+        return 0;
+
+    // initialize the first cut
+    pCut = p->pCuts; p->nCuts = 1;
+    pCut->nNodes = 0; 
+    pCut->nNodesDup = 0;
+    pCut->nLeaves = 1;
+    pCut->pLeaves[0] = p->pObj->Id;
+    // assign the signature
+    Lpk_NodeCutSignature( pCut );
+
+    // perform the cut computation
+    for ( i = 0; i < p->nCuts; i++ )
+    {
+        pCut = p->pCuts + i;
+        if ( pCut->nLeaves == 0 )
+            continue;
+
+        // try to expand the fanins of this cut
+        for ( k = 0; k < (int)pCut->nLeaves; k++ )
+        {
+            // create a new cut
+            Lpk_NodeCutsOne( p, pCut, pCut->pLeaves[k] );
+            // quit if the number of cuts has exceeded the limit
+            if ( p->nCuts == LPK_CUTS_MAX )
+                break;
+        }
+        if ( p->nCuts == LPK_CUTS_MAX )
+            break;
+    }
+    if ( p->nCuts == LPK_CUTS_MAX ) 
+        p->nNodesOver++;
+
+    // record the impact of this node
+    if ( p->pPars->fSatur )
+        Lpk_NodeRecordImpact( p );
+
+    // compress the cuts by removing empty ones, those with negative Weight, and decomposable ones
+    p->nEvals = 0;
+    for ( i = 0; i < p->nCuts; i++ )
+    {
+        pCut = p->pCuts + i;
+        if ( pCut->nLeaves < 2 )
+            continue;
+        // compute the minimum number of LUTs needed to implement this cut
+        // V = N * (K-1) + 1  ~~~~~  N = Ceiling[(V-1)/(K-1)] = (V-1)/(K-1) + [(V-1)%(K-1) > 0]
+        pCut->nLuts = Lpk_LutNumLuts( pCut->nLeaves, p->pPars->nLutSize ); 
+//        pCut->Weight = (float)1.0 * (pCut->nNodes - pCut->nNodesDup - 1) / pCut->nLuts; //p->pPars->nLutsMax;
+        pCut->Weight = (float)1.0 * (pCut->nNodes - pCut->nNodesDup) / pCut->nLuts; //p->pPars->nLutsMax;
+        if ( pCut->Weight <= 1.001 )
+//        if ( pCut->Weight <= 0.999 )
+            continue;
+        pCut->fHasDsd = Lpk_NodeCutsCheckDsd( p, pCut );
+        if ( pCut->fHasDsd )
+            continue;
+        p->pEvals[p->nEvals++] = i;
+    }
+    if ( p->nEvals == 0 )
+        return 0;
+
+    // sort the cuts by Weight
+    do {
+        fChanges = 0;
+        for ( i = 0; i < p->nEvals - 1; i++ )
+        {
+            pCut = p->pCuts + p->pEvals[i];
+            pCut2 = p->pCuts + p->pEvals[i+1];
+            if ( pCut->Weight >= pCut2->Weight - 0.001 )
+                continue;
+            Temp = p->pEvals[i];
+            p->pEvals[i] = p->pEvals[i+1];
+            p->pEvals[i+1] = Temp;
+            fChanges = 1;
+        }
+    } while ( fChanges );
+/*
+    for ( i = 0; i < p->nEvals; i++ )
+    {
+        pCut = p->pCuts + p->pEvals[i];
+        printf( "Cut %3d : W = %5.2f.\n", i, pCut->Weight );
+    }
+    printf( "\n" );
+*/
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkInt.h b/src/opt/lpk/lpkInt.h
new file mode 100644
index 00000000..960599e4
--- /dev/null
+++ b/src/opt/lpk/lpkInt.h
@@ -0,0 +1,246 @@
+/**CFile****************************************************************
+
+  FileName    [lpkInt.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    [Internal declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkInt.h,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __LPK_INT_H__
+#define __LPK_INT_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif 
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "abc.h"
+#include "kit.h"
+#include "if.h"
+#include "lpk.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define LPK_SIZE_MAX             24     // the largest size of the function
+#define LPK_CUTS_MAX            512     // the largest number of cuts considered
+
+typedef struct Lpk_Man_t_ Lpk_Man_t;
+typedef struct Lpk_Cut_t_ Lpk_Cut_t;
+
+struct Lpk_Cut_t_
+{
+    unsigned     nLeaves       : 6;     // (L) the number of leaves
+    unsigned     nNodes        : 6;     // (M) the number of nodes
+    unsigned     nNodesDup     : 6;     // (Q) nodes outside of MFFC
+    unsigned     nLuts         : 6;     // (N) the number of LUTs to try
+    unsigned     unused        : 6;     // unused
+    unsigned     fHasDsd       : 1;     // set to 1 if the cut has structural DSD (and so cannot be used)
+    unsigned     fMark         : 1;     // multipurpose mark
+    unsigned     uSign[2];              // the signature
+    float        Weight;                // the weight of the cut: (M - Q)/N(V)   (the larger the better)
+    int          Gain;                  // the gain achieved using this cut
+    int          pLeaves[LPK_SIZE_MAX]; // the leaves of the cut
+    int          pNodes[LPK_SIZE_MAX];  // the nodes of the cut
+};
+
+struct Lpk_Man_t_
+{
+    // parameters
+    Lpk_Par_t *  pPars;                 // the set of parameters
+    // current representation
+    Abc_Ntk_t *  pNtk;                  // the network
+    Abc_Obj_t *  pObj;                  // the node to resynthesize 
+    // cut representation
+    int          nMffc;                 // the size of MFFC of the node
+    int          nCuts;                 // the total number of cuts    
+    int          nCutsMax;              // the largest possible number of cuts
+    int          nEvals;                // the number of good cuts
+    Lpk_Cut_t    pCuts[LPK_CUTS_MAX];   // the storage for cuts
+    int          pEvals[LPK_CUTS_MAX];  // the good cuts
+    // visited nodes 
+    Vec_Vec_t *  vVisited;
+    // mapping manager
+    If_Man_t *   pIfMan;
+    Vec_Int_t *  vCover; 
+    Vec_Vec_t *  vLevels;
+    // temporary variables
+    int          fCofactoring;          // working in the cofactoring mode
+    int          fCalledOnce;           // limits the depth of MUX cofactoring
+    int          nCalledSRed;           // the number of called to SRed
+    int          pRefs[LPK_SIZE_MAX];   // fanin reference counters 
+    int          pCands[LPK_SIZE_MAX];  // internal nodes pointing only to the leaves
+    Vec_Ptr_t *  vLeaves;
+    // truth table representation
+    Vec_Ptr_t *  vTtElems;              // elementary truth tables
+    Vec_Ptr_t *  vTtNodes;              // storage for temporary truth tables of the nodes 
+    Vec_Int_t *  vMemory;
+    Vec_Int_t *  vBddDir;
+    Vec_Int_t *  vBddInv;
+    unsigned     puSupps[32];           // the supports of the cofactors
+    unsigned *   ppTruths[5][16];
+    // variable sets
+    Vec_Int_t *  vSets[8];
+    Kit_DsdMan_t* pDsdMan;
+    // statistics
+    int          nNodesTotal;           // total number of nodes
+    int          nNodesOver;            // nodes with cuts over the limit 
+    int          nCutsTotal;            // total number of cuts
+    int          nCutsUseful;           // useful cuts 
+    int          nGainTotal;            // the gain in LUTs
+    int          nChanges;              // the number of changed nodes
+    int          nBenefited;            // the number of gainful that benefited from decomposition
+    int          nMuxes;
+    int          nDsds;
+    int          nTotalNets;
+    int          nTotalNets2;
+    int          nTotalNodes;
+    int          nTotalNodes2;
+    // counter of non-DSD blocks
+    int          nBlocks[17];
+    // runtime
+    int          timeCuts;
+    int          timeTruth;
+    int          timeSupps;
+    int          timeTruth2;
+    int          timeTruth3;
+    int          timeEval;
+    int          timeMap;
+    int          timeOther;
+    int          timeTotal;
+    // runtime of eval
+    int          timeEvalMuxAn;
+    int          timeEvalMuxSp;
+    int          timeEvalDsdAn;
+    int          timeEvalDsdSp;
+ 
+};
+
+
+// internal representation of the function to be decomposed
+typedef struct Lpk_Fun_t_ Lpk_Fun_t;
+struct Lpk_Fun_t_
+{
+    Vec_Ptr_t *  vNodes;           // the array of leaves and decomposition nodes
+    unsigned     Id         :  7;  // the ID of this node
+    unsigned     nVars      :  5;  // the number of variables
+    unsigned     nLutK      :  4;  // the number of LUT inputs
+    unsigned     nAreaLim   :  5;  // the area limit (the largest allowed)
+    unsigned     nDelayLim  :  9;  // the delay limit (the largest allowed)
+    unsigned     fSupports  :  1;  // supports of cofactors were precomputed
+    unsigned     fMark      :  1;  // marks the MUX-based dec
+    unsigned     uSupp;            // the support of this component
+    unsigned     puSupps[32];      // the supports of the cofactors
+    char         pDelays[16];      // the delays of the inputs
+    char         pFanins[16];      // the fanins of this function
+    unsigned     pTruth[0];        // the truth table (contains room for three truth tables)    
+};
+
+// preliminary decomposition result
+typedef struct Lpk_Res_t_ Lpk_Res_t;
+struct Lpk_Res_t_
+{
+    int          nBSVars;          // the number of bound set variables
+    unsigned     BSVars;           // the bound set
+    int          nCofVars;         // the number of cofactoring variables
+    char         pCofVars[4];      // the cofactoring variables
+    int          nSuppSizeS;       // support size of the smaller (decomposed) function 
+    int          nSuppSizeL;       // support size of the larger (composition) function
+    int          DelayEst;         // estimated delay of the decomposition
+    int          AreaEst;          // estimated area of the decomposition
+    int          Variable;         // variable in MUX decomposition
+    int          Polarity;         // polarity in MUX decomposition
+};
+
+static inline int        Lpk_LutNumVars( int nLutsLim, int nLutK ) { return  nLutsLim * (nLutK - 1) + 1;                                            }
+static inline int        Lpk_LutNumLuts( int nVarsMax, int nLutK ) { return (nVarsMax - 1) / (nLutK - 1) + (int)((nVarsMax - 1) % (nLutK - 1) > 0); }
+static inline unsigned * Lpk_FunTruth( Lpk_Fun_t * p, int Num )    { assert( Num < 3 ); return p->pTruth + Kit_TruthWordNum(p->nVars) * Num;        }
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                           ITERATORS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define Lpk_CutForEachLeaf( pNtk, pCut, pObj, i )                                        \
+    for ( i = 0; (i < (int)(pCut)->nLeaves) && (((pObj) = Abc_NtkObj(pNtk, (pCut)->pLeaves[i])), 1); i++ )
+#define Lpk_CutForEachNode( pNtk, pCut, pObj, i )                                        \
+    for ( i = 0; (i < (int)(pCut)->nNodes) && (((pObj) = Abc_NtkObj(pNtk, (pCut)->pNodes[i])), 1); i++ )
+#define Lpk_CutForEachNodeReverse( pNtk, pCut, pObj, i )                                 \
+    for ( i = (int)(pCut)->nNodes - 1; (i >= 0) && (((pObj) = Abc_NtkObj(pNtk, (pCut)->pNodes[i])), 1); i-- )
+#define Lpk_SuppForEachVar( Supp, Var )\
+    for ( Var = 0; Var < 16; Var++ )\
+        if ( !(Supp & (1<<Var)) ) {} else
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== lpkAbcDec.c ============================================================*/
+extern Abc_Obj_t *    Lpk_Decompose( Lpk_Man_t * pMan, Abc_Ntk_t * pNtk, Vec_Ptr_t * vLeaves, unsigned * pTruth, unsigned * puSupps, int nLutK, int AreaLim, int DelayLim );
+/*=== lpkAbcDsd.c ============================================================*/
+extern Lpk_Res_t *    Lpk_DsdAnalize( Lpk_Man_t * pMan, Lpk_Fun_t * p, int nShared );
+extern Lpk_Fun_t *    Lpk_DsdSplit( Lpk_Man_t * pMan, Lpk_Fun_t * p, char * pCofVars, int nCofVars, unsigned uBoundSet );
+/*=== lpkAbcMux.c ============================================================*/
+extern Lpk_Res_t *    Lpk_MuxAnalize( Lpk_Man_t * pMan, Lpk_Fun_t * p );
+extern Lpk_Fun_t *    Lpk_MuxSplit( Lpk_Man_t * pMan, Lpk_Fun_t * p, int Var, int Pol );
+/*=== lpkAbcUtil.c ============================================================*/
+extern Lpk_Fun_t *    Lpk_FunAlloc( int nVars );
+extern void           Lpk_FunFree( Lpk_Fun_t * p );
+extern Lpk_Fun_t *    Lpk_FunCreate( Abc_Ntk_t * pNtk, Vec_Ptr_t * vLeaves, unsigned * pTruth, int nLutK, int AreaLim, int DelayLim );
+extern Lpk_Fun_t *    Lpk_FunDup( Lpk_Fun_t * p, unsigned * pTruth );
+extern int            Lpk_FunSuppMinimize( Lpk_Fun_t * p );
+extern void           Lpk_FunComputeCofSupps( Lpk_Fun_t * p );
+extern int            Lpk_SuppDelay( unsigned uSupp, char * pDelays );
+extern int            Lpk_SuppToVars( unsigned uBoundSet, char * pVars );
+
+
+/*=== lpkCut.c =========================================================*/
+extern unsigned *     Lpk_CutTruth( Lpk_Man_t * p, Lpk_Cut_t * pCut, int fInv );
+extern int            Lpk_NodeCuts( Lpk_Man_t * p );
+/*=== lpkMap.c =========================================================*/
+extern Lpk_Man_t *    Lpk_ManStart( Lpk_Par_t * pPars );
+extern void           Lpk_ManStop( Lpk_Man_t * p );
+/*=== lpkMap.c =========================================================*/
+extern If_Obj_t *     Lpk_MapPrime( Lpk_Man_t * p, unsigned * pTruth, int nVars, If_Obj_t ** ppLeaves );
+extern If_Obj_t *     Lpk_MapTree_rec( Lpk_Man_t * p, Kit_DsdNtk_t * pNtk, If_Obj_t ** ppLeaves, int iLit, If_Obj_t * pResult );
+/*=== lpkMulti.c =======================================================*/
+extern If_Obj_t *     Lpk_MapTreeMulti( Lpk_Man_t * p, unsigned * pTruth, int nLeaves, If_Obj_t ** ppLeaves );
+/*=== lpkMux.c =========================================================*/
+extern If_Obj_t *     Lpk_MapTreeMux_rec( Lpk_Man_t * p, unsigned * pTruth, int nVars, If_Obj_t ** ppLeaves );
+extern If_Obj_t *     Lpk_MapSuppRedDec_rec( Lpk_Man_t * p, unsigned * pTruth, int nVars, If_Obj_t ** ppLeaves );
+/*=== lpkSets.c =========================================================*/
+extern unsigned       Lpk_MapSuppRedDecSelect( Lpk_Man_t * p, unsigned * pTruth, int nVars, int * piVar, int * piVarReused );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/lpk/lpkMan.c b/src/opt/lpk/lpkMan.c
new file mode 100644
index 00000000..af6a5307
--- /dev/null
+++ b/src/opt/lpk/lpkMan.c
@@ -0,0 +1,122 @@
+/**CFile****************************************************************
+
+  FileName    [lpkMan.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkMan.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Lpk_Man_t * Lpk_ManStart( Lpk_Par_t * pPars )
+{
+    Lpk_Man_t * p;
+    int i, nWords;
+    assert( pPars->nLutsMax <= 16 );
+    assert( pPars->nVarsMax > 0 && pPars->nVarsMax <= 16 );
+    p = ALLOC( Lpk_Man_t, 1 );
+    memset( p, 0, sizeof(Lpk_Man_t) );
+    p->pPars = pPars;
+    p->nCutsMax = LPK_CUTS_MAX;
+    p->vTtElems = Vec_PtrAllocTruthTables( pPars->nVarsMax );
+    p->vTtNodes = Vec_PtrAllocSimInfo( 1024, Abc_TruthWordNum(pPars->nVarsMax) );
+    p->vCover = Vec_IntAlloc( 1 << 12 );
+    p->vLeaves = Vec_PtrAlloc( 32 );
+    for ( i = 0; i < 8; i++ )
+        p->vSets[i] = Vec_IntAlloc(100);
+    p->pDsdMan = Kit_DsdManAlloc( pPars->nVarsMax, 64 );
+    p->vMemory = Vec_IntAlloc( 1024 * 32 );
+    p->vBddDir = Vec_IntAlloc( 256 );
+    p->vBddInv = Vec_IntAlloc( 256 );
+    // allocate temporary storage for truth tables
+    nWords = Kit_TruthWordNum(pPars->nVarsMax);
+    p->ppTruths[0][0] = ALLOC( unsigned, 32 * nWords );
+    p->ppTruths[1][0] = p->ppTruths[0][0] + 1 * nWords;
+    for ( i = 1; i < 2; i++ )
+        p->ppTruths[1][i] = p->ppTruths[1][0] + i * nWords;
+    p->ppTruths[2][0] = p->ppTruths[1][0] + 2 * nWords;
+    for ( i = 1; i < 4; i++ )
+        p->ppTruths[2][i] = p->ppTruths[2][0] + i * nWords;
+    p->ppTruths[3][0] = p->ppTruths[2][0] + 4 * nWords; 
+    for ( i = 1; i < 8; i++ )
+        p->ppTruths[3][i] = p->ppTruths[3][0] + i * nWords;
+    p->ppTruths[4][0] = p->ppTruths[3][0] + 8 * nWords; 
+    for ( i = 1; i < 16; i++ )
+        p->ppTruths[4][i] = p->ppTruths[4][0] + i * nWords;
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_ManStop( Lpk_Man_t * p )
+{
+    int i;
+    free( p->ppTruths[0][0] );
+    Vec_IntFree( p->vBddDir );
+    Vec_IntFree( p->vBddInv );
+    Vec_IntFree( p->vMemory );
+    Kit_DsdManFree( p->pDsdMan );
+    for ( i = 0; i < 8; i++ )
+        Vec_IntFree(p->vSets[i]);
+    if ( p->pIfMan )
+    {
+        void * pPars = p->pIfMan->pPars;
+        If_ManStop( p->pIfMan );
+        free( pPars );
+    }
+    if ( p->vLevels )
+        Vec_VecFree( p->vLevels );
+    if ( p->vVisited )
+        Vec_VecFree( p->vVisited );
+    Vec_PtrFree( p->vLeaves );
+    Vec_IntFree( p->vCover );
+    Vec_PtrFree( p->vTtElems );
+    Vec_PtrFree( p->vTtNodes );
+    free( p );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkMap.c b/src/opt/lpk/lpkMap.c
new file mode 100644
index 00000000..698aeea1
--- /dev/null
+++ b/src/opt/lpk/lpkMap.c
@@ -0,0 +1,205 @@
+/**CFile****************************************************************
+
+  FileName    [lpkMap.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkMap.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Transforms the decomposition graph into the AIG.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+If_Obj_t * Lpk_MapPrimeInternal( If_Man_t * pIfMan, Kit_Graph_t * pGraph )
+{
+    Kit_Node_t * pNode;
+    If_Obj_t * pAnd0, * pAnd1;
+    int i;
+    // check for constant function
+    if ( Kit_GraphIsConst(pGraph) )
+        return If_ManConst1(pIfMan);
+    // check for a literal
+    if ( Kit_GraphIsVar(pGraph) )
+        return Kit_GraphVar(pGraph)->pFunc;
+    // build the AIG nodes corresponding to the AND gates of the graph
+    Kit_GraphForEachNode( pGraph, pNode, i )
+    {
+        pAnd0 = Kit_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc; 
+        pAnd1 = Kit_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc; 
+        pNode->pFunc = If_ManCreateAnd( pIfMan, 
+            If_NotCond( If_Regular(pAnd0), If_IsComplement(pAnd0) ^ pNode->eEdge0.fCompl ), 
+            If_NotCond( If_Regular(pAnd1), If_IsComplement(pAnd1) ^ pNode->eEdge1.fCompl ) );
+    }
+    return pNode->pFunc;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Strashes one logic node using its SOP.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+If_Obj_t * Lpk_MapPrime( Lpk_Man_t * p, unsigned * pTruth, int nVars, If_Obj_t ** ppLeaves )
+{
+    Kit_Graph_t * pGraph;
+    Kit_Node_t * pNode;
+    If_Obj_t * pRes;
+    int i;
+    // derive the factored form
+    pGraph = Kit_TruthToGraph( pTruth, nVars, p->vCover );
+    if ( pGraph == NULL )
+        return NULL;
+    // collect the fanins
+    Kit_GraphForEachLeaf( pGraph, pNode, i )
+        pNode->pFunc = ppLeaves[i];
+    // perform strashing
+    pRes = Lpk_MapPrimeInternal( p->pIfMan, pGraph );
+    pRes = If_NotCond( pRes, Kit_GraphIsComplement(pGraph) );
+    Kit_GraphFree( pGraph );
+    return pRes;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares the mapping manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+If_Obj_t * Lpk_MapTree_rec( Lpk_Man_t * p, Kit_DsdNtk_t * pNtk, If_Obj_t ** ppLeaves, int iLit, If_Obj_t * pResult )
+{
+    Kit_DsdObj_t * pObj;
+    If_Obj_t * pObjNew = NULL, * pObjNew2 = NULL, * pFansNew[16];
+    unsigned i, iLitFanin;
+
+    assert( iLit >= 0 );
+
+    // consider the case of a gate
+    pObj = Kit_DsdNtkObj( pNtk, Kit_DsdLit2Var(iLit) );
+    if ( pObj == NULL )
+    {
+        pObjNew = ppLeaves[Kit_DsdLit2Var(iLit)];
+        return If_NotCond( pObjNew, Kit_DsdLitIsCompl(iLit) );
+    }
+    if ( pObj->Type == KIT_DSD_CONST1 )
+    {
+        return If_NotCond( If_ManConst1(p->pIfMan), Kit_DsdLitIsCompl(iLit) );
+    }
+    if ( pObj->Type == KIT_DSD_VAR )
+    {
+        pObjNew = ppLeaves[Kit_DsdLit2Var(pObj->pFans[0])];
+        return If_NotCond( pObjNew, Kit_DsdLitIsCompl(iLit) ^ Kit_DsdLitIsCompl(pObj->pFans[0]) );
+    }
+    if ( pObj->Type == KIT_DSD_AND )
+    {
+        assert( pObj->nFans == 2 );
+        pFansNew[0] = Lpk_MapTree_rec( p, pNtk, ppLeaves, pObj->pFans[0], NULL );
+        pFansNew[1] = pResult? pResult : Lpk_MapTree_rec( p, pNtk, ppLeaves, pObj->pFans[1], NULL );
+        if ( pFansNew[0] == NULL || pFansNew[1] == NULL )
+            return NULL;
+        pObjNew = If_ManCreateAnd( p->pIfMan, pFansNew[0], pFansNew[1] ); 
+        return If_NotCond( pObjNew, Kit_DsdLitIsCompl(iLit) );
+    }
+    if ( pObj->Type == KIT_DSD_XOR )
+    {
+        int fCompl = Kit_DsdLitIsCompl(iLit);
+        assert( pObj->nFans == 2 );
+        pFansNew[0] = Lpk_MapTree_rec( p, pNtk, ppLeaves, pObj->pFans[0], NULL );
+        pFansNew[1] = pResult? pResult : Lpk_MapTree_rec( p, pNtk, ppLeaves, pObj->pFans[1], NULL );
+        if ( pFansNew[0] == NULL || pFansNew[1] == NULL )
+            return NULL;
+        fCompl ^= If_IsComplement(pFansNew[0]) ^ If_IsComplement(pFansNew[1]);
+        pObjNew = If_ManCreateXor( p->pIfMan, If_Regular(pFansNew[0]), If_Regular(pFansNew[1]) );
+        return If_NotCond( pObjNew, fCompl );
+    }
+    assert( pObj->Type == KIT_DSD_PRIME );
+    p->nBlocks[pObj->nFans]++;
+
+    // solve for the inputs
+    Kit_DsdObjForEachFanin( pNtk, pObj, iLitFanin, i )
+    {
+        if ( i == 0 )
+            pFansNew[i] = pResult? pResult : Lpk_MapTree_rec( p, pNtk, ppLeaves, iLitFanin, NULL );
+        else
+            pFansNew[i] = Lpk_MapTree_rec( p, pNtk, ppLeaves, iLitFanin, NULL );
+        if ( pFansNew[i] == NULL )
+            return NULL;
+    }
+/* 
+    if ( !p->fCofactoring && p->pPars->nVarsShared > 0 && (int)pObj->nFans > p->pPars->nLutSize )
+    {
+        pObjNew = Lpk_MapTreeMulti( p, Kit_DsdObjTruth(pObj), pObj->nFans, pFansNew );
+        return If_NotCond( pObjNew, Kit_DsdLitIsCompl(iLit) );
+    }
+*/
+/*
+    if ( (int)pObj->nFans > p->pPars->nLutSize )
+    {
+        pObjNew2 = Lpk_MapTreeMux_rec( p, Kit_DsdObjTruth(pObj), pObj->nFans, pFansNew );
+//        if ( pObjNew2 )
+//            return If_NotCond( pObjNew2, Kit_DsdLitIsCompl(iLit) );
+    }
+*/
+
+    // find best cofactoring variable
+    if ( p->pPars->nVarsShared > 0 && (int)pObj->nFans > p->pPars->nLutSize )
+    {
+        pObjNew2 = Lpk_MapSuppRedDec_rec( p, Kit_DsdObjTruth(pObj), pObj->nFans, pFansNew );
+        if ( pObjNew2 )
+            return If_NotCond( pObjNew2, Kit_DsdLitIsCompl(iLit) );
+    }
+
+    pObjNew = Lpk_MapPrime( p, Kit_DsdObjTruth(pObj), pObj->nFans, pFansNew );
+
+    // add choice
+    if ( pObjNew && pObjNew2 )
+    {
+        If_ObjSetChoice( If_Regular(pObjNew), If_Regular(pObjNew2) );
+        If_ManCreateChoice( p->pIfMan, If_Regular(pObjNew) );
+    }
+    return If_NotCond( pObjNew, Kit_DsdLitIsCompl(iLit) );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkMulti.c b/src/opt/lpk/lpkMulti.c
new file mode 100644
index 00000000..82cf3578
--- /dev/null
+++ b/src/opt/lpk/lpkMulti.c
@@ -0,0 +1,495 @@
+/**CFile****************************************************************
+
+  FileName    [lpkMulti.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkMulti.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Records variable order.]
+
+  Description [Increaments Order[x][y] by 1 if x should be above y in the DSD.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_CreateVarOrder( Kit_DsdNtk_t * pNtk, char pTable[][16] )
+{
+    Kit_DsdObj_t * pObj;
+    unsigned uSuppFanins, k;
+    int Above[16], Below[16];
+    int nAbove, nBelow, iFaninLit, i, x, y;
+    // iterate through the nodes
+    Kit_DsdNtkForEachObj( pNtk, pObj, i )
+    {
+        // collect fanin support of this node
+        nAbove = 0;
+        uSuppFanins = 0;
+        Kit_DsdObjForEachFanin( pNtk, pObj, iFaninLit, k )
+        {
+            if ( Kit_DsdLitIsLeaf( pNtk, iFaninLit ) )
+                Above[nAbove++] = Kit_DsdLit2Var(iFaninLit);
+            else
+                uSuppFanins |= Kit_DsdLitSupport( pNtk, iFaninLit );
+        }
+        // find the below variables
+        nBelow = 0;
+        for ( y = 0; y < 16; y++ )
+            if ( uSuppFanins & (1 << y) )
+                Below[nBelow++] = y;
+        // create all pairs
+        for ( x = 0; x < nAbove; x++ )
+            for ( y = 0; y < nBelow; y++ )
+                pTable[Above[x]][Below[y]]++;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates commmon variable order.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_CreateCommonOrder( char pTable[][16], int piCofVar[], int nCBars, int pPrios[], int nVars, int fVerbose )
+{
+    int Score[16] = {0}, pPres[16];
+    int i, y, x, iVarBest, ScoreMax, PrioCount;
+
+    // mark the present variables
+    for ( i = 0; i < nVars; i++ )
+        pPres[i] = 1;
+    // remove cofactored variables
+    for ( i = 0; i < nCBars; i++ )
+        pPres[piCofVar[i]] = 0;
+
+    // compute scores for each leaf
+    for ( i = 0; i < nVars; i++ )
+    {
+        if ( pPres[i] == 0 )
+            continue;
+        for ( y = 0; y < nVars; y++ )
+            Score[i] += pTable[i][y];
+        for ( x = 0; x < nVars; x++ )
+            Score[i] -= pTable[x][i];
+    }
+
+    // print the scores
+    if ( fVerbose )
+    {
+        printf( "Scores: " );
+        for ( i = 0; i < nVars; i++ )
+            printf( "%c=%d ", 'a'+i, Score[i] );
+        printf( "   " );
+        printf( "Prios: " );
+    }
+
+    // derive variable priority
+    // variables with equal score receive the same priority
+    for ( i = 0; i < nVars; i++ )
+        pPrios[i] = 16;
+
+    // iterate until variables remain
+    for ( PrioCount = 1; ; PrioCount++ )
+    {
+        // find the present variable with the highest score
+        iVarBest = -1;
+        ScoreMax = -100000;
+        for ( i = 0; i < nVars; i++ )
+        {
+            if ( pPres[i] == 0 )
+                continue;
+            if ( ScoreMax < Score[i] )
+            {
+                ScoreMax = Score[i];
+                iVarBest = i;
+            }
+        }
+        if ( iVarBest == -1 )
+            break;
+        // give the next priority to all vars having this score
+        if ( fVerbose )
+            printf( "%d=", PrioCount );
+        for ( i = 0; i < nVars; i++ )
+        {
+            if ( pPres[i] == 0 )
+                continue;
+            if ( Score[i] == ScoreMax )
+            {
+                pPrios[i] = PrioCount;
+                pPres[i] = 0;
+                if ( fVerbose )
+                    printf( "%c", 'a'+i );
+            }
+        }
+        if ( fVerbose )
+            printf( " " );
+    }
+    if ( fVerbose )
+        printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finds components with the highest priority.]
+
+  Description [Returns the number of components selected.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_FindHighest( Kit_DsdNtk_t ** ppNtks, int * piLits, int nSize, int * pPrio, int * pDecision )
+{
+    Kit_DsdObj_t * pObj;
+    unsigned uSupps[8], uSuppFanin, uSuppTotal, uSuppLarge;
+    int i, pTriv[8], PrioMin, iVarMax, nComps, fOneNonTriv;
+
+    // find individual support and total support 
+    uSuppTotal = 0;
+    for ( i = 0; i < nSize; i++ )
+    {
+        pTriv[i] = 1;
+        if ( piLits[i] < 0 ) 
+            uSupps[i] = 0;
+        else if ( Kit_DsdLitIsLeaf(ppNtks[i], piLits[i]) )
+            uSupps[i] = Kit_DsdLitSupport( ppNtks[i], piLits[i] );
+        else
+        {
+            pObj = Kit_DsdNtkObj( ppNtks[i], Kit_DsdLit2Var(piLits[i]) );
+            if ( pObj->Type == KIT_DSD_PRIME )
+            {
+                pTriv[i] = 0;
+                uSuppFanin = Kit_DsdLitSupport( ppNtks[i], pObj->pFans[0] );
+            }
+            else
+            {
+                assert( pObj->nFans == 2 );
+                if ( !Kit_DsdLitIsLeaf(ppNtks[i], pObj->pFans[0]) )
+                    pTriv[i] = 0;
+                uSuppFanin = Kit_DsdLitSupport( ppNtks[i], pObj->pFans[1] );
+            }
+            uSupps[i] = Kit_DsdLitSupport( ppNtks[i], piLits[i] ) & ~uSuppFanin;
+        }
+        assert( uSupps[i] <= 0xFFFF );
+        uSuppTotal |= uSupps[i];
+    }
+    if ( uSuppTotal == 0 )
+        return 0;
+
+    // find one support variable with the highest priority
+    PrioMin = ABC_INFINITY;
+    iVarMax = -1;
+    for ( i = 0; i < 16; i++ )
+        if ( uSuppTotal & (1 << i) )
+            if ( PrioMin > pPrio[i] )
+            {
+                PrioMin = pPrio[i];
+                iVarMax = i;
+            }
+    assert( iVarMax != -1 );
+
+    // select components, which have this variable
+    nComps = 0;
+    fOneNonTriv = 0;
+    uSuppLarge = 0;
+    for ( i = 0; i < nSize; i++ )
+        if ( uSupps[i] & (1<<iVarMax) )
+        {
+            if ( pTriv[i] || !fOneNonTriv )
+            {
+                if ( !pTriv[i] )
+                {
+                    uSuppLarge = uSupps[i];
+                    fOneNonTriv = 1;
+                }
+                pDecision[i] = 1;
+                nComps++;
+            }
+            else
+                pDecision[i] = 0;
+        }
+        else
+            pDecision[i] = 0;
+
+    // add other non-trivial not-taken components whose support is contained in the current large component support
+    if ( fOneNonTriv )
+        for ( i = 0; i < nSize; i++ )
+            if ( !pTriv[i] && pDecision[i] == 0 && (uSupps[i] & ~uSuppLarge) == 0 )
+            {
+                pDecision[i] = 1;
+                nComps++;
+            }
+
+    return nComps;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares the mapping manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+If_Obj_t * Lpk_MapTreeMulti_rec( Lpk_Man_t * p, Kit_DsdNtk_t ** ppNtks, int * piLits, int * piCofVar, int nCBars, If_Obj_t ** ppLeaves, int nLeaves, int * pPrio )
+{
+    Kit_DsdObj_t * pObj;
+    If_Obj_t * pObjsNew[4][8], * pResPrev;
+    int piLitsNew[8], pDecision[8];
+    int i, k, nComps, nSize;
+
+    // find which of the variables is highest in the order
+    nSize = (1 << nCBars);
+    nComps = Lpk_FindHighest( ppNtks, piLits, nSize, pPrio, pDecision );
+    if ( nComps == 0 )
+        return If_Not( If_ManConst1(p->pIfMan) );
+
+    // iterate over the nodes
+    if ( p->pPars->fVeryVerbose )
+        printf( "Decision: " );
+    for ( i = 0; i < nSize; i++ )
+    {
+        if ( pDecision[i] )
+        {
+            if ( p->pPars->fVeryVerbose )
+                printf( "%d ", i );
+            assert( piLits[i] >= 0 );
+            pObj = Kit_DsdNtkObj( ppNtks[i], Kit_DsdLit2Var(piLits[i]) );
+            if ( pObj == NULL )
+                piLitsNew[i] = -2;
+            else if ( pObj->Type == KIT_DSD_PRIME )
+                piLitsNew[i] = pObj->pFans[0];
+            else
+                piLitsNew[i] = pObj->pFans[1];
+        }
+        else
+            piLitsNew[i] = piLits[i];
+    }
+    if ( p->pPars->fVeryVerbose )
+        printf( "\n" );
+
+    // call again
+    pResPrev = Lpk_MapTreeMulti_rec( p, ppNtks, piLitsNew, piCofVar, nCBars, ppLeaves, nLeaves, pPrio );
+
+    // create new set of nodes
+    for ( i = 0; i < nSize; i++ )
+    {
+        if ( pDecision[i] )
+            pObjsNew[nCBars][i] = Lpk_MapTree_rec( p, ppNtks[i], ppLeaves, piLits[i], pResPrev );
+        else if ( piLits[i] == -1 )
+            pObjsNew[nCBars][i] = If_ManConst1(p->pIfMan);
+        else if ( piLits[i] == -2 )
+            pObjsNew[nCBars][i] = If_Not( If_ManConst1(p->pIfMan) );
+        else
+            pObjsNew[nCBars][i] = pResPrev;
+    }
+
+    // create MUX using these outputs
+    for ( k = nCBars; k > 0; k-- )
+    {
+        nSize /= 2;
+        for ( i = 0; i < nSize; i++ )
+            pObjsNew[k-1][i] = If_ManCreateMux( p->pIfMan, pObjsNew[k][2*i+0], pObjsNew[k][2*i+1], ppLeaves[piCofVar[k-1]] );
+    }
+    assert( nSize == 1 );
+    return pObjsNew[0][0];  
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares the mapping manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+If_Obj_t * Lpk_MapTreeMulti( Lpk_Man_t * p, unsigned * pTruth, int nVars, If_Obj_t ** ppLeaves )
+{
+    static Counter = 0;
+    If_Obj_t * pResult;
+    Kit_DsdNtk_t * ppNtks[8] = {0}, * pTemp;
+    Kit_DsdObj_t * pRoot;
+    int piCofVar[4], pPrios[16], pFreqs[16] = {0}, piLits[16];
+    int i, k, nCBars, nSize, nMemSize;
+    unsigned * ppCofs[4][8], uSupport;
+    char pTable[16][16] = {0};
+    int fVerbose = p->pPars->fVeryVerbose;
+
+    Counter++;
+//    printf( "Run %d.\n", Counter );
+
+    // allocate storage for cofactors
+    nMemSize = Kit_TruthWordNum(nVars);
+    ppCofs[0][0] = ALLOC( unsigned, 32 * nMemSize );
+    nSize = 0;
+    for ( i = 0; i < 4; i++ )
+    for ( k = 0; k < 8; k++ )
+        ppCofs[i][k] = ppCofs[0][0] + nMemSize * nSize++;
+    assert( nSize == 32 );
+
+    // find the best cofactoring variables
+    nCBars = Kit_DsdCofactoring( pTruth, nVars, piCofVar, p->pPars->nVarsShared, 0 );
+//    nCBars = 2;
+//    piCofVar[0] = 0;
+//    piCofVar[1] = 1;
+
+
+    // copy the function
+    Kit_TruthCopy( ppCofs[0][0], pTruth, nVars );
+
+    // decompose w.r.t. these variables
+    for ( k = 0; k < nCBars; k++ )
+    {
+        nSize = (1 << k);
+        for ( i = 0; i < nSize; i++ )
+        {
+            Kit_TruthCofactor0New( ppCofs[k+1][2*i+0], ppCofs[k][i], nVars, piCofVar[k] );
+            Kit_TruthCofactor1New( ppCofs[k+1][2*i+1], ppCofs[k][i], nVars, piCofVar[k] );
+        }
+    }
+    nSize = (1 << nCBars);
+    // compute DSD networks
+    for ( i = 0; i < nSize; i++ )
+    {
+        ppNtks[i] = Kit_DsdDecompose( ppCofs[nCBars][i], nVars );
+        ppNtks[i] = Kit_DsdExpand( pTemp = ppNtks[i] );
+        Kit_DsdNtkFree( pTemp );
+        if ( fVerbose )
+        {
+            printf( "Cof%d%d: ", nCBars, i );
+            Kit_DsdPrint( stdout, ppNtks[i] );
+        }
+    }
+
+    // compute variable frequences
+    for ( i = 0; i < nSize; i++ )
+    {
+        uSupport = Kit_TruthSupport( ppCofs[nCBars][i], nVars );
+        for ( k = 0; k < nVars; k++ )
+            if ( uSupport & (1<<k) )
+                pFreqs[k]++;
+    }
+
+    // find common variable order
+    for ( i = 0; i < nSize; i++ )
+    {
+        Kit_DsdGetSupports( ppNtks[i] );
+        Lpk_CreateVarOrder( ppNtks[i], pTable );
+    }
+    Lpk_CreateCommonOrder( pTable, piCofVar, nCBars, pPrios, nVars, fVerbose );
+    // update priorities with frequences
+    for ( i = 0; i < nVars; i++ )
+        pPrios[i] = pPrios[i] * 256 + (16 - pFreqs[i]) * 16 + i;
+
+    if ( fVerbose )
+        printf( "After restructuring with priority:\n" );
+
+    if ( Counter == 1 )
+    {
+        int x = 0;
+    }
+    // transform all networks according to the variable order
+    for ( i = 0; i < nSize; i++ )
+    {
+        ppNtks[i] = Kit_DsdShrink( pTemp = ppNtks[i], pPrios );
+        Kit_DsdNtkFree( pTemp );
+        Kit_DsdGetSupports( ppNtks[i] );
+        assert( ppNtks[i]->pSupps[0] <= 0xFFFF );
+        // undec nodes should be rotated in such a way that the first input has as many shared inputs as possible
+        Kit_DsdRotate( ppNtks[i], pFreqs );
+        // print the resulting networks
+        if ( fVerbose )
+        {
+            printf( "Cof%d%d: ", nCBars, i );
+            Kit_DsdPrint( stdout, ppNtks[i] );
+        }
+    }
+ 
+    for ( i = 0; i < nSize; i++ )
+    {
+        // collect the roots
+        pRoot = Kit_DsdNtkRoot(ppNtks[i]);
+        if ( pRoot->Type == KIT_DSD_CONST1 )
+            piLits[i] = Kit_DsdLitIsCompl(ppNtks[i]->Root)? -2: -1;
+        else if ( pRoot->Type == KIT_DSD_VAR )
+            piLits[i] = Kit_DsdLitNotCond( pRoot->pFans[0], Kit_DsdLitIsCompl(ppNtks[i]->Root) );
+        else
+            piLits[i] = ppNtks[i]->Root;
+    }
+
+
+    // recursively construct AIG for mapping
+    p->fCofactoring = 1;
+    pResult = Lpk_MapTreeMulti_rec( p, ppNtks, piLits, piCofVar, nCBars, ppLeaves, nVars, pPrios );
+    p->fCofactoring = 0;
+
+    if ( fVerbose )
+        printf( "\n" );
+
+    // verify the transformations
+    nSize = (1 << nCBars);
+    for ( i = 0; i < nSize; i++ )
+        Kit_DsdTruth( ppNtks[i], ppCofs[nCBars][i] );
+    // mux the truth tables
+    for ( k = nCBars-1; k >= 0; k-- )
+    {
+        nSize = (1 << k);
+        for ( i = 0; i < nSize; i++ )
+            Kit_TruthMuxVar( ppCofs[k][i], ppCofs[k+1][2*i+0], ppCofs[k+1][2*i+1], nVars, piCofVar[k] );
+    }
+    if ( !Extra_TruthIsEqual( pTruth, ppCofs[0][0], nVars ) )
+        printf( "Verification failed.\n" );
+
+
+    // free the networks
+    for ( i = 0; i < 8; i++ )
+        if ( ppNtks[i] )
+            Kit_DsdNtkFree( ppNtks[i] );
+    free( ppCofs[0][0] );
+
+    return pResult;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkMux.c b/src/opt/lpk/lpkMux.c
new file mode 100644
index 00000000..ed046ad7
--- /dev/null
+++ b/src/opt/lpk/lpkMux.c
@@ -0,0 +1,247 @@
+/**CFile****************************************************************
+
+  FileName    [lpkMux.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkMux.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Find the best cofactoring variable.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Lpk_MapTreeBestCofVar( Lpk_Man_t * p, unsigned * pTruth, int nVars, unsigned * pCof0, unsigned * pCof1 )
+{
+    int i, iBestVar, nSuppSizeCur0, nSuppSizeCur1, nSuppSizeCur, nSuppSizeMin;
+    // iterate through variables
+    iBestVar = -1;
+    nSuppSizeMin = KIT_INFINITY;
+    for ( i = 0; i < nVars; i++ )
+    {
+        // cofactor the functiona and get support sizes
+        Kit_TruthCofactor0New( pCof0, pTruth, nVars, i );
+        Kit_TruthCofactor1New( pCof1, pTruth, nVars, i );
+        nSuppSizeCur0 = Kit_TruthSupportSize( pCof0, nVars );
+        nSuppSizeCur1 = Kit_TruthSupportSize( pCof1, nVars );
+        nSuppSizeCur  = nSuppSizeCur0 + nSuppSizeCur1;
+        // skip cofactoring that goes above the limit
+        if ( nSuppSizeCur0 > p->pPars->nLutSize || nSuppSizeCur1 > p->pPars->nLutSize )
+            continue;
+        // compare this variable with other variables
+        if ( nSuppSizeMin > nSuppSizeCur ) 
+        {
+            nSuppSizeMin = nSuppSizeCur;
+            iBestVar = i;
+        }
+    }
+    // cofactor w.r.t. this variable
+    if ( iBestVar != -1 )
+    {
+        Kit_TruthCofactor0New( pCof0, pTruth, nVars, iBestVar );
+        Kit_TruthCofactor1New( pCof1, pTruth, nVars, iBestVar );
+    }
+    return iBestVar;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Maps the function by the best cofactoring.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+If_Obj_t * Lpk_MapTreeMux_rec( Lpk_Man_t * p, unsigned * pTruth, int nVars, If_Obj_t ** ppLeaves )
+{
+    unsigned * pCof0 = Vec_PtrEntry( p->vTtNodes, 0 );
+    unsigned * pCof1 = Vec_PtrEntry( p->vTtNodes, 1 );
+    If_Obj_t * pObj0, * pObj1;
+    Kit_DsdNtk_t * ppNtks[2];
+    int iBestVar;
+    assert( nVars > 3 );
+    p->fCalledOnce = 1;
+    // cofactor w.r.t. the best variable
+    iBestVar = Lpk_MapTreeBestCofVar( p, pTruth, nVars, pCof0, pCof1 );
+    if ( iBestVar == -1 )
+        return NULL;
+    // decompose the functions
+    ppNtks[0] = Kit_DsdDecompose( pCof0, nVars );
+    ppNtks[1] = Kit_DsdDecompose( pCof1, nVars );
+    if ( p->pPars->fVeryVerbose )
+    {
+        printf( "Cofactoring w.r.t. var %c (%d -> %d+%d supp vars):\n", 
+            'a'+iBestVar, nVars, Kit_TruthSupportSize(pCof0, nVars), Kit_TruthSupportSize(pCof1, nVars) );
+        Kit_DsdPrintExpanded( ppNtks[0] );
+        Kit_DsdPrintExpanded( ppNtks[1] );
+    }
+    // map the DSD structures
+    pObj0 = Lpk_MapTree_rec( p, ppNtks[0], ppLeaves, ppNtks[0]->Root, NULL );
+    pObj1 = Lpk_MapTree_rec( p, ppNtks[1], ppLeaves, ppNtks[1]->Root, NULL );
+    Kit_DsdNtkFree( ppNtks[0] );
+    Kit_DsdNtkFree( ppNtks[1] );
+    return If_ManCreateMux( p->pIfMan, pObj0, pObj1, ppLeaves[iBestVar] );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Implements support-reducing decomposition.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+If_Obj_t * Lpk_MapSuppRedDec_rec( Lpk_Man_t * p, unsigned * pTruth, int nVars, If_Obj_t ** ppLeaves )
+{
+    Kit_DsdNtk_t * pNtkDec, * pNtkComp, * ppNtks[2], * pTemp;
+    If_Obj_t * pObjNew;
+    unsigned * pCof0 = Vec_PtrEntry( p->vTtNodes,  0 );
+    unsigned * pCof1 = Vec_PtrEntry( p->vTtNodes,  1 );
+    unsigned * pDec0 = Vec_PtrEntry( p->vTtNodes,  2 );
+    unsigned * pDec1 = Vec_PtrEntry( p->vTtNodes,  3 );
+    unsigned * pDec  = Vec_PtrEntry( p->vTtNodes,  4 );
+    unsigned * pCo00 = Vec_PtrEntry( p->vTtNodes,  5 );
+    unsigned * pCo01 = Vec_PtrEntry( p->vTtNodes,  6 );
+    unsigned * pCo10 = Vec_PtrEntry( p->vTtNodes,  7 );
+    unsigned * pCo11 = Vec_PtrEntry( p->vTtNodes,  8 );
+    unsigned * pCo0  = Vec_PtrEntry( p->vTtNodes,  9 );
+    unsigned * pCo1  = Vec_PtrEntry( p->vTtNodes, 10 );
+    unsigned * pCo   = Vec_PtrEntry( p->vTtNodes, 11 );
+    int TrueMint0, TrueMint1, FalseMint0, FalseMint1;
+    int uSubsets, uSubset0, uSubset1, iVar, iVarReused, i;
+
+    // determine if supp-red decomposition exists
+    uSubsets = Lpk_MapSuppRedDecSelect( p, pTruth, nVars, &iVar, &iVarReused );
+    if ( uSubsets == 0 )
+        return NULL;
+    p->nCalledSRed++;
+
+    // get the cofactors
+    Kit_TruthCofactor0New( pCof0, pTruth, nVars, iVar );
+    Kit_TruthCofactor1New( pCof1, pTruth, nVars, iVar );
+
+    // get the bound sets
+    uSubset0 = uSubsets & 0xFFFF;
+    uSubset1 = uSubsets >> 16;
+
+    // compute the decomposed functions
+    ppNtks[0] = Kit_DsdDecompose( pCof0, nVars );
+    ppNtks[1] = Kit_DsdDecompose( pCof1, nVars );
+    ppNtks[0] = Kit_DsdExpand( pTemp = ppNtks[0] );      Kit_DsdNtkFree( pTemp );
+    ppNtks[1] = Kit_DsdExpand( pTemp = ppNtks[1] );      Kit_DsdNtkFree( pTemp );
+    Kit_DsdTruthPartial( p->pDsdMan, ppNtks[0], pDec0, uSubset0 );
+    Kit_DsdTruthPartial( p->pDsdMan, ppNtks[1], pDec1, uSubset1 );
+//    Kit_DsdTruthPartialTwo( p->pDsdMan, ppNtks[0], uSubset0, iVarReused, pCo0, pDec0 );
+//    Kit_DsdTruthPartialTwo( p->pDsdMan, ppNtks[1], uSubset1, iVarReused, pCo1, pDec1 );
+    Kit_DsdNtkFree( ppNtks[0] );
+    Kit_DsdNtkFree( ppNtks[1] );
+//Kit_DsdPrintFromTruth( pDec0, nVars );
+//Kit_DsdPrintFromTruth( pDec1, nVars );
+    // get the decomposed function
+    Kit_TruthMuxVar( pDec, pDec0, pDec1, nVars, iVar );
+
+    // find any true assignments of the decomposed functions
+    TrueMint0 = Kit_TruthFindFirstBit( pDec0, nVars );
+    TrueMint1 = Kit_TruthFindFirstBit( pDec1, nVars );
+    assert( TrueMint0 >= 0 && TrueMint1 >= 0 );
+    // find any false assignments of the decomposed functions
+    FalseMint0 = Kit_TruthFindFirstZero( pDec0, nVars );
+    FalseMint1 = Kit_TruthFindFirstZero( pDec1, nVars );
+    assert( FalseMint0 >= 0 && FalseMint1 >= 0 );
+
+    // cofactor the cofactors according to these minterms
+    Kit_TruthCopy( pCo00, pCof0, nVars );
+    Kit_TruthCopy( pCo01, pCof0, nVars );
+    for ( i = 0; i < nVars; i++ )
+        if ( uSubset0 & (1 << i) )
+        {
+            if ( FalseMint0 & (1 << i) )
+                Kit_TruthCofactor1( pCo00, nVars, i );
+            else
+                Kit_TruthCofactor0( pCo00, nVars, i );
+            if ( TrueMint0 & (1 << i) )
+                Kit_TruthCofactor1( pCo01, nVars, i );
+            else
+                Kit_TruthCofactor0( pCo01, nVars, i );
+        }
+    Kit_TruthCopy( pCo10, pCof1, nVars );
+    Kit_TruthCopy( pCo11, pCof1, nVars );
+    for ( i = 0; i < nVars; i++ )
+        if ( uSubset1 & (1 << i) )
+        {
+            if ( FalseMint1 & (1 << i) )
+                Kit_TruthCofactor1( pCo10, nVars, i );
+            else
+                Kit_TruthCofactor0( pCo10, nVars, i );
+            if ( TrueMint1 & (1 << i) )
+                Kit_TruthCofactor1( pCo11, nVars, i );
+            else
+                Kit_TruthCofactor0( pCo11, nVars, i );
+        }
+
+    // derive the functions by composing them with the new variable (iVarReused)
+    Kit_TruthMuxVar( pCo0, pCo00, pCo01, nVars, iVarReused );
+    Kit_TruthMuxVar( pCo1, pCo10, pCo11, nVars, iVarReused );
+//Kit_DsdPrintFromTruth( pCo0, nVars );
+//Kit_DsdPrintFromTruth( pCo1, nVars );
+
+    // derive the composition function
+    Kit_TruthMuxVar( pCo , pCo0 , pCo1 , nVars, iVar );
+
+    // process the decomposed function
+    pNtkDec = Kit_DsdDecompose( pDec, nVars );
+    pNtkComp = Kit_DsdDecompose( pCo, nVars );
+//Kit_DsdPrint( stdout, pNtkDec );
+//Kit_DsdPrint( stdout, pNtkComp );
+//printf( "cofactored variable %c\n", 'a' + iVar );
+//printf( "reused variable %c\n", 'a' + iVarReused );
+
+    ppLeaves[iVarReused] = Lpk_MapTree_rec( p, pNtkDec, ppLeaves, pNtkDec->Root, NULL );
+    pObjNew = Lpk_MapTree_rec( p, pNtkComp, ppLeaves, pNtkComp->Root, NULL );
+
+    Kit_DsdNtkFree( pNtkDec );
+    Kit_DsdNtkFree( pNtkComp );
+    return pObjNew;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpkSets.c b/src/opt/lpk/lpkSets.c
new file mode 100644
index 00000000..90e46863
--- /dev/null
+++ b/src/opt/lpk/lpkSets.c
@@ -0,0 +1,440 @@
+/**CFile****************************************************************
+
+  FileName    [lpkSets.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpkSets.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Lpk_Set_t_ Lpk_Set_t;
+struct Lpk_Set_t_
+{
+    char         iVar;        // the cofactoring variable
+    char         Over;        // the overlap in supports
+    char         SRed;        // the support reduction
+    char         Size;        // the size of the boundset
+    unsigned     uSubset0;    // the first subset (with removed)
+    unsigned     uSubset1;    // the second subset (with removed)
+};
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively computes decomposable subsets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Lpk_ComputeSets_rec( Kit_DsdNtk_t * p, int iLit, Vec_Int_t * vSets )
+{
+    unsigned i, iLitFanin, uSupport, uSuppCur;
+    Kit_DsdObj_t * pObj;
+    // consider the case of simple gate
+    pObj = Kit_DsdNtkObj( p, Kit_DsdLit2Var(iLit) );
+    if ( pObj == NULL )
+        return (1 << Kit_DsdLit2Var(iLit));
+    if ( pObj->Type == KIT_DSD_AND || pObj->Type == KIT_DSD_XOR )
+    {
+        unsigned uSupps[16], Limit, s;
+        uSupport = 0;
+        Kit_DsdObjForEachFanin( p, pObj, iLitFanin, i )
+        {
+            uSupps[i] = Lpk_ComputeSets_rec( p, iLitFanin, vSets );
+            uSupport |= uSupps[i];
+        }
+        // create all subsets, except empty and full
+        Limit = (1 << pObj->nFans) - 1;
+        for ( s = 1; s < Limit; s++ )
+        {
+            uSuppCur = 0;
+            for ( i = 0; i < pObj->nFans; i++ )
+                if ( s & (1 << i) )
+                    uSuppCur |= uSupps[i];
+            Vec_IntPush( vSets, uSuppCur );
+        }
+        return uSupport;
+    }
+    assert( pObj->Type == KIT_DSD_PRIME );
+    // get the cumulative support of all fanins
+    uSupport = 0;
+    Kit_DsdObjForEachFanin( p, pObj, iLitFanin, i )
+    {
+        uSuppCur  = Lpk_ComputeSets_rec( p, iLitFanin, vSets );
+        uSupport |= uSuppCur;
+        Vec_IntPush( vSets, uSuppCur );
+    }
+    return uSupport;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the set of subsets of decomposable variables.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Lpk_ComputeSets( Kit_DsdNtk_t * p, Vec_Int_t * vSets )
+{
+    unsigned uSupport, Entry;
+    int Number, i;
+    assert( p->nVars <= 16 );
+    Vec_IntClear( vSets );
+    Vec_IntPush( vSets, 0 );
+    if ( Kit_DsdNtkRoot(p)->Type == KIT_DSD_CONST1 )
+        return 0;
+    if ( Kit_DsdNtkRoot(p)->Type == KIT_DSD_VAR )
+    {
+        uSupport = ( 1 << Kit_DsdLit2Var(Kit_DsdNtkRoot(p)->pFans[0]) );
+        Vec_IntPush( vSets, uSupport );
+        return uSupport;
+    }
+    uSupport = Lpk_ComputeSets_rec( p, p->Root, vSets );
+    assert( (uSupport & 0xFFFF0000) == 0 );
+    Vec_IntPush( vSets, uSupport );
+    // set the remaining variables
+    Vec_IntForEachEntry( vSets, Number, i )
+    {
+        Entry = Number;
+        Vec_IntWriteEntry( vSets, i, Entry | ((uSupport & ~Entry) << 16) );
+    }
+    return uSupport;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the sets of subsets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static void Lpk_PrintSetOne( int uSupport )
+{
+    unsigned k;
+    for ( k = 0; k < 16; k++ )
+        if ( uSupport & (1<<k) )
+            printf( "%c", 'a'+k );
+    printf( " " );
+}
+/**Function*************************************************************
+
+  Synopsis    [Prints the sets of subsets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static void Lpk_PrintSets( Vec_Int_t * vSets )
+{
+    unsigned uSupport;
+    int Number, i;
+    printf( "Subsets(%d): ", Vec_IntSize(vSets) );
+    Vec_IntForEachEntry( vSets, Number, i )
+    {
+        uSupport = Number;
+        Lpk_PrintSetOne( uSupport );
+    }
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes maximal support reducing bound-sets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_ComposeSets( Vec_Int_t * vSets0, Vec_Int_t * vSets1, int nVars, int iCofVar,
+    Lpk_Set_t * pStore, int * pSize, int nSizeLimit )
+{
+    static int nTravId = 0;            // the number of the times this is visited
+    static int TravId[1<<16] = {0};    // last visited
+    static char SRed[1<<16];           // best support reduction
+    static char Over[1<<16];           // best overlaps
+    static unsigned Parents[1<<16];    // best set of parents
+    static unsigned short Used[1<<16]; // storage for used subsets
+    int nSuppSize, nSuppOver, nSuppRed, nUsed, nMinOver, i, k, s;
+    unsigned Entry, Entry0, Entry1;
+    unsigned uSupp, uSupp0, uSupp1, uSuppTotal;
+    Lpk_Set_t * pEntry;
+
+    if ( nTravId == (1 << 30) )
+        memset( TravId, 0, sizeof(int) * (1 << 16) );
+
+    // collect support reducing subsets
+    nUsed = 0;
+    nTravId++;
+    uSuppTotal = Kit_BitMask(nVars) & ~(1<<iCofVar);
+    Vec_IntForEachEntry( vSets0, Entry0, i )
+    Vec_IntForEachEntry( vSets1, Entry1, k )
+    {
+        uSupp0 = (Entry0 & 0xFFFF);
+        uSupp1 = (Entry1 & 0xFFFF);
+        // skip trivial
+        if ( uSupp0 == 0 || uSupp1 == 0 || (uSupp0 | uSupp1) == uSuppTotal )
+            continue;
+        if ( Kit_WordHasOneBit(uSupp0) && Kit_WordHasOneBit(uSupp1) )
+            continue;
+        // get the entry
+        Entry = Entry0 | Entry1;
+        uSupp = Entry & 0xFFFF;
+        // set the bound set size
+        nSuppSize = Kit_WordCountOnes( uSupp );
+        // get the number of overlapping vars
+        nSuppOver = Kit_WordCountOnes( Entry & (Entry >> 16) );
+        // get the support reduction
+        nSuppRed  = nSuppSize - 1 - nSuppOver;
+        // only consider support-reducing subsets
+        if ( nSuppRed <= 0 )
+            continue;
+        // check if this support is already used
+        if ( TravId[uSupp] < nTravId )
+        {
+            Used[nUsed++] = uSupp;
+
+            TravId[uSupp] = nTravId;
+            SRed[uSupp] = nSuppRed;
+            Over[uSupp] = nSuppOver;
+            Parents[uSupp] = (k << 16) | i;
+        }
+        else if ( TravId[uSupp] == nTravId && SRed[uSupp] < nSuppRed )
+        {
+            TravId[uSupp] = nTravId;
+            SRed[uSupp] = nSuppRed;
+            Over[uSupp] = nSuppOver;
+            Parents[uSupp] = (k << 16) | i;
+        }
+    }
+
+    // find the minimum overlap
+    nMinOver = 1000;
+    for ( s = 0; s < nUsed; s++ )
+        if ( nMinOver > Over[Used[s]] )
+            nMinOver = Over[Used[s]];
+
+
+    // collect the accumulated ones
+    for ( s = 0; s < nUsed; s++ )
+        if ( Over[Used[s]] == nMinOver )
+        {
+            // save the entry
+            if ( *pSize == nSizeLimit )
+                return;
+            pEntry = pStore + (*pSize)++;
+
+            i = Parents[Used[s]] & 0xFFFF;
+            k = Parents[Used[s]] >> 16;
+
+            pEntry->uSubset0 = Vec_IntEntry(vSets0, i);
+            pEntry->uSubset1 = Vec_IntEntry(vSets1, k);
+            Entry  = pEntry->uSubset0 | pEntry->uSubset1;
+
+            // record the cofactoring variable
+            pEntry->iVar = iCofVar;
+            // set the bound set size
+            pEntry->Size = Kit_WordCountOnes( Entry & 0xFFFF );
+            // get the number of overlapping vars
+            pEntry->Over = Kit_WordCountOnes( Entry & (Entry >> 16) );
+            // get the support reduction
+            pEntry->SRed = pEntry->Size - 1 - pEntry->Over;
+            assert( pEntry->SRed > 0 );
+        }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints one set.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Lpk_MapSuppPrintSet( Lpk_Set_t * pSet, int i )
+{
+    unsigned Entry;
+    Entry = pSet->uSubset0 | pSet->uSubset1;
+    printf( "%2d : ", i );
+    printf( "Var = %c  ",  'a' + pSet->iVar );
+    printf( "Size = %2d  ", pSet->Size );
+    printf( "Over = %2d  ", pSet->Over );
+    printf( "SRed = %2d  ", pSet->SRed );
+    Lpk_PrintSetOne( Entry );
+    printf( "              " );
+    Lpk_PrintSetOne( Entry >> 16 );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Evaluates the cofactors.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Lpk_MapSuppRedDecSelect( Lpk_Man_t * p, unsigned * pTruth, int nVars, int * piVar, int * piVarReused )
+{
+    static int nStoreSize = 256;
+    static Lpk_Set_t pStore[256], * pSet, * pSetBest;
+    Kit_DsdNtk_t * ppNtks[2], * pTemp;
+    Vec_Int_t * vSets0 = p->vSets[0];
+    Vec_Int_t * vSets1 = p->vSets[1];
+    unsigned * pCof0 = Vec_PtrEntry( p->vTtNodes, 0 );
+    unsigned * pCof1 = Vec_PtrEntry( p->vTtNodes, 1 );
+    int nSets, i, SizeMax;//, SRedMax;
+    unsigned Entry;
+    int fVerbose = p->pPars->fVeryVerbose;
+//    int fVerbose = 0;
+
+    // collect decomposable subsets for each pair of cofactors
+    if ( fVerbose )
+    {
+        printf( "\nExploring support-reducing bound-sets of function:\n" );
+        Kit_DsdPrintFromTruth( pTruth, nVars );
+    }
+    nSets = 0;
+    for ( i = 0; i < nVars; i++ )
+    {
+        if ( fVerbose )
+        printf( "Evaluating variable %c:\n", 'a'+i );
+        // evaluate the cofactor pair
+        Kit_TruthCofactor0New( pCof0, pTruth, nVars, i );
+        Kit_TruthCofactor1New( pCof1, pTruth, nVars, i );
+        // decompose and expand
+        ppNtks[0] = Kit_DsdDecompose( pCof0, nVars );
+        ppNtks[1] = Kit_DsdDecompose( pCof1, nVars );
+        ppNtks[0] = Kit_DsdExpand( pTemp = ppNtks[0] );      Kit_DsdNtkFree( pTemp );
+        ppNtks[1] = Kit_DsdExpand( pTemp = ppNtks[1] );      Kit_DsdNtkFree( pTemp );
+        if ( fVerbose )
+        Kit_DsdPrint( stdout, ppNtks[0] );
+        if ( fVerbose )
+        Kit_DsdPrint( stdout, ppNtks[1] );
+        // compute subsets
+        Lpk_ComputeSets( ppNtks[0], vSets0 );
+        Lpk_ComputeSets( ppNtks[1], vSets1 );
+        // print subsets
+        if ( fVerbose )
+        Lpk_PrintSets( vSets0 );
+        if ( fVerbose )
+        Lpk_PrintSets( vSets1 );
+        // free the networks
+        Kit_DsdNtkFree( ppNtks[0] );
+        Kit_DsdNtkFree( ppNtks[1] );
+        // evaluate the pair
+        Lpk_ComposeSets( vSets0, vSets1, nVars, i, pStore, &nSets, nStoreSize );
+    }
+
+    // print the results
+    if ( fVerbose )
+    printf( "\n" );
+    if ( fVerbose )
+    for ( i = 0; i < nSets; i++ )
+        Lpk_MapSuppPrintSet( pStore + i, i );
+
+    // choose the best subset
+    SizeMax = 0;
+    pSetBest = NULL;
+    for ( i = 0; i < nSets; i++ )
+    {
+        pSet = pStore + i;
+        if ( pSet->Size > p->pPars->nLutSize - 1 )
+            continue;
+        if ( SizeMax < pSet->Size )
+        {
+            pSetBest = pSet;
+            SizeMax = pSet->Size;
+        }
+    }
+/*
+    // if the best is not choosen, select the one with largest reduction
+    SRedMax = 0;
+    if ( pSetBest == NULL )
+    {
+        for ( i = 0; i < nSets; i++ )
+        {
+            pSet = pStore + i;
+            if ( SRedMax < pSet->SRed )
+            {
+                pSetBest = pSet;
+                SRedMax = pSet->SRed;
+            }
+        }
+    }
+*/
+    if ( pSetBest == NULL )
+    {
+        if ( fVerbose )
+        printf( "Could not select a subset.\n" );
+        return 0;
+    }
+    else
+    {
+        if ( fVerbose )
+        printf( "Selected the following subset:\n" );
+        if ( fVerbose )
+        Lpk_MapSuppPrintSet( pSetBest, pSetBest - pStore );
+    }
+
+    // prepare the return result
+    // get the remaining variables
+    Entry = ((pSetBest->uSubset0 >> 16) | (pSetBest->uSubset1 >> 16));
+    // get the variables to be removed
+    Entry = Kit_BitMask(nVars) & ~(1<<pSetBest->iVar) & ~Entry;
+    // make sure there are some - otherwise it is not supp-red
+    assert( Entry );
+    // remember the first such variable
+    *piVarReused = Kit_WordFindFirstBit( Entry );
+    *piVar = pSetBest->iVar;
+    return (pSetBest->uSubset1 << 16) | (pSetBest->uSubset0 & 0xFFFF);
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/lpk_.c b/src/opt/lpk/lpk_.c
new file mode 100644
index 00000000..d8555e08
--- /dev/null
+++ b/src/opt/lpk/lpk_.c
@@ -0,0 +1,48 @@
+/**CFile****************************************************************
+
+  FileName    [lpk_.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Fast Boolean matching for LUT structures.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - April 28, 2007.]
+
+  Revision    [$Id: lpk_.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "lpkInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/lpk/module.make b/src/opt/lpk/module.make
new file mode 100644
index 00000000..26a54894
--- /dev/null
+++ b/src/opt/lpk/module.make
@@ -0,0 +1,11 @@
+SRC +=    src/opt/lpk/lpkCore.c \
+    src/opt/lpk/lpkAbcDec.c \
+    src/opt/lpk/lpkAbcMux.c \
+    src/opt/lpk/lpkAbcDsd.c \
+    src/opt/lpk/lpkAbcUtil.c \
+    src/opt/lpk/lpkCut.c \
+    src/opt/lpk/lpkMan.c \
+    src/opt/lpk/lpkMap.c \
+    src/opt/lpk/lpkMulti.c \
+    src/opt/lpk/lpkMux.c \
+    src/opt/lpk/lpkSets.c 
diff --git a/src/opt/res/module.make b/src/opt/res/module.make
new file mode 100644
index 00000000..52d8a315
--- /dev/null
+++ b/src/opt/res/module.make
@@ -0,0 +1,7 @@
+SRC +=  src/opt/res/resCore.c \
+    src/opt/res/resDivs.c \
+    src/opt/res/resFilter.c \
+    src/opt/res/resSat.c \
+    src/opt/res/resSim.c \
+    src/opt/res/resStrash.c \
+    src/opt/res/resWin.c
diff --git a/src/opt/res/res.h b/src/opt/res/res.h
new file mode 100644
index 00000000..3c3431bf
--- /dev/null
+++ b/src/opt/res/res.h
@@ -0,0 +1,75 @@
+/**CFile****************************************************************
+
+  FileName    [res.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: res.h,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __RES_H__
+#define __RES_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Res_Par_t_ Res_Par_t;
+struct Res_Par_t_
+{
+    // general parameters
+    int           nWindow;       // window size
+    int           nGrowthLevel;  // the maximum allowed growth in level after one iteration of resynthesis
+    int           nSimWords;     // the number of simulation words 
+    int           nCands;        // the number of candidates to try
+    int           fArea;         // performs optimization for area
+    int           fDelay;        // performs optimization for delay
+    int           fVerbose;      // enable basic stats
+    int           fVeryVerbose;  // enable detailed stats
+};
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== resCore.c ==========================================================*/
+extern int        Abc_NtkResynthesize( Abc_Ntk_t * pNtk, Res_Par_t * pPars );
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/res/resCore.c b/src/opt/res/resCore.c
new file mode 100644
index 00000000..27e9b3ea
--- /dev/null
+++ b/src/opt/res/resCore.c
@@ -0,0 +1,415 @@
+/**CFile****************************************************************
+
+  FileName    [resCore.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Top-level resynthesis procedure.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resCore.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+#include "kit.h"
+#include "satStore.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Res_Man_t_ Res_Man_t;
+struct Res_Man_t_
+{
+    // general parameters
+    Res_Par_t *   pPars;
+    // specialized manager
+    Res_Win_t *   pWin;          // windowing manager
+    Abc_Ntk_t *   pAig;          // the strashed window
+    Res_Sim_t *   pSim;          // simulation manager
+    Sto_Man_t *   pCnf;          // the CNF of the SAT problem
+    Int_Man_t *   pMan;          // interpolation manager;
+    Vec_Int_t *   vMem;          // memory for intermediate SOPs
+    Vec_Vec_t *   vResubs;       // resubstitution candidates of the AIG
+    Vec_Vec_t *   vResubsW;      // resubstitution candidates of the window
+    Vec_Vec_t *   vLevels;       // levelized structure for updating
+    // statistics
+    int           nWins;         // the number of windows tried
+    int           nWinNodes;     // the total number of window nodes
+    int           nDivNodes;     // the total number of divisors
+    int           nWinsTriv;     // the total number of trivial windows
+    int           nWinsUsed;     // the total number of useful windows (with at least one candidate)
+    int           nConstsUsed;   // the total number of constant nodes under ODC
+    int           nCandSets;     // the total number of candidates
+    int           nProvedSets;   // the total number of proved groups
+    int           nSimEmpty;     // the empty simulation info
+    int           nTotalNets;    // the total number of nets
+    int           nTotalNodes;   // the total number of nodess
+    int           nTotalNets2;   // the total number of nets
+    int           nTotalNodes2;  // the total number of nodess
+    // runtime
+    int           timeWin;       // windowing
+    int           timeDiv;       // divisors
+    int           timeAig;       // strashing
+    int           timeSim;       // simulation
+    int           timeCand;      // resubstitution candidates
+    int           timeSatTotal;  // SAT solving total 
+    int           timeSatSat;    // SAT solving (sat calls)
+    int           timeSatUnsat;  // SAT solving (unsat calls)
+    int           timeSatSim;    // SAT solving (simulation)
+    int           timeInt;       // interpolation 
+    int           timeUpd;       // updating  
+    int           timeTotal;     // total runtime
+};
+
+extern Hop_Obj_t * Kit_GraphToHop( Hop_Man_t * pMan, Kit_Graph_t * pGraph );
+
+extern int s_ResynTime;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocate resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Res_Man_t * Res_ManAlloc( Res_Par_t * pPars )
+{
+    Res_Man_t * p;
+    p = ALLOC( Res_Man_t, 1 );
+    memset( p, 0, sizeof(Res_Man_t) );
+    assert( pPars->nWindow > 0 && pPars->nWindow < 100 );
+    assert( pPars->nCands > 0 && pPars->nCands < 100 );
+    p->pPars = pPars;
+    p->pWin = Res_WinAlloc();
+    p->pSim = Res_SimAlloc( pPars->nSimWords );
+    p->pMan = Int_ManAlloc( 512 );
+    p->vMem = Vec_IntAlloc( 0 );
+    p->vResubs  = Vec_VecStart( pPars->nCands );
+    p->vResubsW = Vec_VecStart( pPars->nCands );
+    p->vLevels  = Vec_VecStart( 32 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deallocate resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_ManFree( Res_Man_t * p )
+{
+    if ( p->pPars->fVerbose )
+    {
+        printf( "Reduction in nodes = %5d. (%.2f %%) ", 
+            p->nTotalNodes-p->nTotalNodes2, 
+            100.0*(p->nTotalNodes-p->nTotalNodes2)/p->nTotalNodes );
+        printf( "Reduction in edges = %5d. (%.2f %%) ", 
+            p->nTotalNets-p->nTotalNets2, 
+            100.0*(p->nTotalNets-p->nTotalNets2)/p->nTotalNets );
+        printf( "\n" );
+
+        printf( "Winds = %d. ", p->nWins );
+        printf( "Nodes = %d. (Ave = %5.1f)  ", p->nWinNodes, 1.0*p->nWinNodes/p->nWins );
+        printf( "Divs = %d. (Ave = %5.1f)  ",  p->nDivNodes, 1.0*p->nDivNodes/p->nWins );
+        printf( "\n" );
+        printf( "WinsTriv = %d. ", p->nWinsTriv );
+        printf( "SimsEmpt = %d. ", p->nSimEmpty );
+        printf( "Const = %d. ", p->nConstsUsed );
+        printf( "WindUsed = %d. ", p->nWinsUsed );
+        printf( "Cands = %d. ", p->nCandSets );
+        printf( "Proved = %d.", p->nProvedSets );
+        printf( "\n" );
+
+        PRTP( "Windowing  ", p->timeWin,      p->timeTotal );
+        PRTP( "Divisors   ", p->timeDiv,      p->timeTotal );
+        PRTP( "Strashing  ", p->timeAig,      p->timeTotal );
+        PRTP( "Simulation ", p->timeSim,      p->timeTotal );
+        PRTP( "Candidates ", p->timeCand,     p->timeTotal );
+        PRTP( "SAT solver ", p->timeSatTotal, p->timeTotal );
+        PRTP( "    sat    ", p->timeSatSat,   p->timeTotal );
+        PRTP( "    unsat  ", p->timeSatUnsat, p->timeTotal );
+        PRTP( "    simul  ", p->timeSatSim,   p->timeTotal );
+        PRTP( "Interpol   ", p->timeInt,      p->timeTotal );
+        PRTP( "Undating   ", p->timeUpd,      p->timeTotal );
+        PRTP( "TOTAL      ", p->timeTotal,    p->timeTotal );
+    }
+    Res_WinFree( p->pWin );
+    if ( p->pAig ) Abc_NtkDelete( p->pAig );
+    Res_SimFree( p->pSim );
+    if ( p->pCnf ) Sto_ManFree( p->pCnf );
+    Int_ManFree( p->pMan );
+    Vec_IntFree( p->vMem );
+    Vec_VecFree( p->vResubs );
+    Vec_VecFree( p->vResubsW );
+    Vec_VecFree( p->vLevels );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Incrementally updates level of the nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_UpdateNetwork( Abc_Obj_t * pObj, Vec_Ptr_t * vFanins, Hop_Obj_t * pFunc, Vec_Vec_t * vLevels )
+{
+    Abc_Obj_t * pObjNew, * pFanin;
+    int k;
+    // create the new node
+    pObjNew = Abc_NtkCreateNode( pObj->pNtk );
+    pObjNew->pData = pFunc;
+    Vec_PtrForEachEntry( vFanins, pFanin, k )
+        Abc_ObjAddFanin( pObjNew, pFanin );
+    // replace the old node by the new node
+    // update the level of the node
+    Abc_NtkUpdate( pObj, pObjNew, vLevels );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Entrace into the resynthesis package.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkResynthesize( Abc_Ntk_t * pNtk, Res_Par_t * pPars )
+{
+    ProgressBar * pProgress;
+    Res_Man_t * p;
+    Abc_Obj_t * pObj;
+    Hop_Obj_t * pFunc;
+    Kit_Graph_t * pGraph;
+    Vec_Ptr_t * vFanins;
+    unsigned * puTruth;
+    int i, k, RetValue, nNodesOld, nFanins, nFaninsMax;
+    int clk, clkTotal = clock();
+
+    // start the manager
+    p = Res_ManAlloc( pPars );
+    p->nTotalNets = Abc_NtkGetTotalFanins(pNtk);
+    p->nTotalNodes = Abc_NtkNodeNum(pNtk);
+    nFaninsMax = Abc_NtkGetFaninMax(pNtk);
+
+    // perform the network sweep
+    Abc_NtkSweep( pNtk, 0 );
+
+    // convert into the AIG
+    if ( !Abc_NtkToAig(pNtk) )
+    {
+        fprintf( stdout, "Converting to BDD has failed.\n" );
+        Res_ManFree( p );
+        return 0;
+    }
+    assert( Abc_NtkHasAig(pNtk) );
+
+    // set the number of levels
+    Abc_NtkLevel( pNtk );
+    Abc_NtkStartReverseLevels( pNtk, pPars->nGrowthLevel );
+
+    // try resynthesizing nodes in the topological order
+    nNodesOld = Abc_NtkObjNumMax(pNtk);
+    pProgress = Extra_ProgressBarStart( stdout, nNodesOld );
+    Abc_NtkForEachObj( pNtk, pObj, i )
+    {
+        Extra_ProgressBarUpdate( pProgress, i, NULL );
+        if ( !Abc_ObjIsNode(pObj) )
+            continue;
+        if ( pObj->Id > nNodesOld )
+            break;
+
+        // create the window for this node
+clk = clock();
+        RetValue = Res_WinCompute( pObj, p->pPars->nWindow/10, p->pPars->nWindow%10, p->pWin );
+p->timeWin += clock() - clk;
+        if ( !RetValue )
+            continue;
+        p->nWinsTriv += Res_WinIsTrivial( p->pWin );
+
+        if ( p->pPars->fVeryVerbose )
+        {
+            printf( "%5d (lev=%2d) : ", pObj->Id, pObj->Level );
+            printf( "Win = %3d/%3d/%4d/%3d   ", 
+                Vec_PtrSize(p->pWin->vLeaves), 
+                Vec_PtrSize(p->pWin->vBranches),
+                Vec_PtrSize(p->pWin->vNodes), 
+                Vec_PtrSize(p->pWin->vRoots) );
+        }
+
+        // collect the divisors
+clk = clock();
+        Res_WinDivisors( p->pWin, Abc_ObjRequiredLevel(pObj) - 1 );
+p->timeDiv += clock() - clk;
+
+        p->nWins++;
+        p->nWinNodes += Vec_PtrSize(p->pWin->vNodes);
+        p->nDivNodes += Vec_PtrSize( p->pWin->vDivs);
+
+        if ( p->pPars->fVeryVerbose )
+        {
+            printf( "D = %3d ", Vec_PtrSize(p->pWin->vDivs) );
+            printf( "D+ = %3d ", p->pWin->nDivsPlus );
+        }
+
+        // create the AIG for the window
+clk = clock();
+        if ( p->pAig ) Abc_NtkDelete( p->pAig );
+        p->pAig = Res_WndStrash( p->pWin );
+p->timeAig += clock() - clk;
+
+        if ( p->pPars->fVeryVerbose )
+        {
+            printf( "AIG = %4d ", Abc_NtkNodeNum(p->pAig) );
+            printf( "\n" );
+        }
+ 
+        // prepare simulation info
+clk = clock();
+        RetValue = Res_SimPrepare( p->pSim, p->pAig, Vec_PtrSize(p->pWin->vLeaves), 0 ); //p->pPars->fVerbose );
+p->timeSim += clock() - clk;
+        if ( !RetValue )
+        {
+            p->nSimEmpty++;
+            continue;
+        }
+
+        // consider the case of constant node
+        if ( p->pSim->fConst0 || p->pSim->fConst1 )
+        {
+            p->nConstsUsed++;
+
+            pFunc = p->pSim->fConst1? Hop_ManConst1(pNtk->pManFunc) : Hop_ManConst0(pNtk->pManFunc);
+            vFanins = Vec_VecEntry( p->vResubsW, 0 );
+            Vec_PtrClear( vFanins );
+            Res_UpdateNetwork( pObj, vFanins, pFunc, p->vLevels );
+            continue;
+        }
+
+//        printf( " " );
+
+        // find resub candidates for the node
+clk = clock();
+        if ( p->pPars->fArea )
+            RetValue = Res_FilterCandidates( p->pWin, p->pAig, p->pSim, p->vResubs, p->vResubsW, nFaninsMax, 1 );
+        else
+            RetValue = Res_FilterCandidates( p->pWin, p->pAig, p->pSim, p->vResubs, p->vResubsW, nFaninsMax, 0 );
+p->timeCand += clock() - clk;
+        p->nCandSets += RetValue;
+        if ( RetValue == 0 )
+            continue;
+
+//        printf( "%d(%d) ", Vec_PtrSize(p->pWin->vDivs), RetValue );
+
+        p->nWinsUsed++;
+
+        // iterate through candidate resubstitutions
+        Vec_VecForEachLevel( p->vResubs, vFanins, k )
+        {
+            if ( Vec_PtrSize(vFanins) == 0 )
+                break;
+
+            // solve the SAT problem and get clauses
+clk = clock();
+            if ( p->pCnf ) Sto_ManFree( p->pCnf );
+            p->pCnf = Res_SatProveUnsat( p->pAig, vFanins );
+            if ( p->pCnf == NULL )
+            {
+p->timeSatSat += clock() - clk;
+//                printf( " Sat\n" );
+//                printf( "-" );
+                continue;
+            }
+p->timeSatUnsat += clock() - clk;
+//            printf( "+" );
+
+            p->nProvedSets++;
+//            printf( " Unsat\n" );
+//            continue;
+//            printf( "Proved %d.\n", k );
+
+            // write it into a file
+//            Sto_ManDumpClauses( p->pCnf, "trace.cnf" );
+
+            // interpolate the problem if it was UNSAT
+clk = clock();
+            nFanins = Int_ManInterpolate( p->pMan, p->pCnf, 0, &puTruth );
+p->timeInt += clock() - clk;
+            if ( nFanins != Vec_PtrSize(vFanins) - 2 )
+                continue;
+            assert( puTruth );
+//            Extra_PrintBinary( stdout, puTruth, 1 << nFanins );  printf( "\n" );
+
+            // transform interpolant into the AIG
+            pGraph = Kit_TruthToGraph( puTruth, nFanins, p->vMem );
+
+            // derive the AIG for the decomposition tree
+            pFunc = Kit_GraphToHop( pNtk->pManFunc, pGraph );
+            Kit_GraphFree( pGraph );
+
+            // update the network
+clk = clock();
+            Res_UpdateNetwork( pObj, Vec_VecEntry(p->vResubsW, k), pFunc, p->vLevels );
+p->timeUpd += clock() - clk;
+            break;
+        }
+//        printf( "\n" );
+    }
+    Extra_ProgressBarStop( pProgress );
+    Abc_NtkStopReverseLevels( pNtk );
+
+p->timeSatSim += p->pSim->timeSat;
+p->timeSatTotal = p->timeSatSat + p->timeSatUnsat + p->timeSatSim;
+
+    p->nTotalNets2 = Abc_NtkGetTotalFanins(pNtk);
+    p->nTotalNodes2 = Abc_NtkNodeNum(pNtk);
+
+    // quit resubstitution manager
+p->timeTotal = clock() - clkTotal;
+    Res_ManFree( p );
+
+s_ResynTime += clock() - clkTotal;
+    // check the resulting network
+    if ( !Abc_NtkCheck( pNtk ) )
+    {
+        fprintf( stdout, "Abc_NtkResynthesize(): Network check has failed.\n" );
+        return 0;
+    }
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/resDivs.c b/src/opt/res/resDivs.c
new file mode 100644
index 00000000..cc75b90f
--- /dev/null
+++ b/src/opt/res/resDivs.c
@@ -0,0 +1,285 @@
+/**CFile****************************************************************
+
+  FileName    [resDivs.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Collect divisors for the given window.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resDivs.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Res_WinMarkTfi( Res_Win_t * p );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Adds candidate divisors of the node to its window.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinDivisors( Res_Win_t * p, int nLevDivMax )
+{
+    Abc_Obj_t * pObj, * pFanout, * pFanin;
+    int k, f, m;
+
+    // set the maximum level of the divisors
+    p->nLevDivMax = nLevDivMax;
+
+    // mark the TFI with the current trav ID
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Res_WinMarkTfi( p );
+
+    // mark with the current trav ID those nodes that should not be divisors:
+    // (1) the node and its TFO
+    // (2) the MFFC of the node
+    // (3) the node's fanins (these are treated as a special case)
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Res_WinSweepLeafTfo_rec( p->pNode, p->nLevDivMax );
+    Res_WinVisitMffc( p->pNode );
+    Abc_ObjForEachFanin( p->pNode, pObj, k )
+        Abc_NodeSetTravIdCurrent( pObj );
+
+    // at this point the nodes are marked with two trav IDs:
+    // nodes to be collected as divisors are marked with previous trav ID
+    // nodes to be avoided as divisors are marked with current trav ID
+
+    // start collecting the divisors
+    Vec_PtrClear( p->vDivs );
+    Vec_PtrForEachEntry( p->vLeaves, pObj, k )
+    {
+        assert( (int)pObj->Level >= p->nLevLeafMin ); 
+        if ( !Abc_NodeIsTravIdPrevious(pObj) )
+            continue;
+        if ( (int)pObj->Level > p->nLevDivMax )
+            continue;
+        Vec_PtrPush( p->vDivs, pObj );
+    }
+    // add the internal nodes to the data structure
+    Vec_PtrForEachEntry( p->vNodes, pObj, k )
+    {
+        if ( !Abc_NodeIsTravIdPrevious(pObj) )
+            continue;
+        if ( (int)pObj->Level > p->nLevDivMax )
+            continue;
+        Vec_PtrPush( p->vDivs, pObj );
+    }
+
+    // explore the fanouts of already collected divisors
+    p->nDivsPlus = 0;
+    Vec_PtrForEachEntry( p->vDivs, pObj, k )
+    {
+        // consider fanouts of this node
+        Abc_ObjForEachFanout( pObj, pFanout, f )
+        {
+            // stop if there are too many fanouts
+            if ( f > 20 )
+                break;
+            // skip nodes that are already added
+            if ( Abc_NodeIsTravIdPrevious(pFanout) )
+                continue;
+            // skip nodes in the TFO or in the MFFC of node
+            if ( Abc_NodeIsTravIdCurrent(pFanout) )
+                continue;
+            // skip COs
+            if ( !Abc_ObjIsNode(pFanout) ) 
+                continue;
+            // skip nodes with large level
+            if ( (int)pFanout->Level >= p->nLevDivMax )
+                continue;
+            // skip nodes whose fanins are not divisors
+            Abc_ObjForEachFanin( pFanout, pFanin, m )
+                if ( !Abc_NodeIsTravIdPrevious(pFanin) )
+                    break;
+            if ( m < Abc_ObjFaninNum(pFanout) )
+                continue;
+            // add the node to the divisors
+            Vec_PtrPush( p->vDivs, pFanout );
+            Vec_PtrPush( p->vNodes, pFanout );
+            Abc_NodeSetTravIdPrevious( pFanout );
+            p->nDivsPlus++;
+        }
+    }
+/*
+    printf( "Node level = %d.  ", Abc_ObjLevel(p->pNode) );
+    Vec_PtrForEachEntryStart( p->vDivs, pObj, k, Vec_PtrSize(p->vDivs)-p->nDivsPlus )
+        printf( "%d ", Abc_ObjLevel(pObj) );
+    printf( "\n" );
+*/
+//printf( "%d ", p->nDivsPlus );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the TFI cone of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinMarkTfi_rec( Res_Win_t * p, Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pFanin;
+    int i;
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return;
+    Abc_NodeSetTravIdCurrent( pObj );
+    assert( Abc_ObjIsNode(pObj) );
+    // visit the fanins of the node
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+        Res_WinMarkTfi_rec( p, pFanin );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the TFI cone of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinMarkTfi( Res_Win_t * p )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    // mark the leaves
+    Vec_PtrForEachEntry( p->vLeaves, pObj, i )
+        Abc_NodeSetTravIdCurrent( pObj );
+    // start from the node
+    Res_WinMarkTfi_rec( p, p->pNode );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the TFO of the collected nodes up to the given level.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinSweepLeafTfo_rec( Abc_Obj_t * pObj, int nLevelLimit )
+{
+    Abc_Obj_t * pFanout;
+    int i;
+    if ( Abc_ObjIsCo(pObj) || (int)pObj->Level > nLevelLimit )
+        return;
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return;
+    Abc_NodeSetTravIdCurrent( pObj );
+    Abc_ObjForEachFanout( pObj, pFanout, i )
+        Res_WinSweepLeafTfo_rec( pFanout, nLevelLimit );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Dereferences the node's MFFC.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_NodeDeref_rec( Abc_Obj_t * pNode )
+{
+    Abc_Obj_t * pFanin;
+    int i, Counter = 1;
+    if ( Abc_ObjIsCi(pNode) )
+        return 0;
+    Abc_NodeSetTravIdCurrent( pNode );
+    Abc_ObjForEachFanin( pNode, pFanin, i )
+    {
+        assert( pFanin->vFanouts.nSize > 0 );
+        if ( --pFanin->vFanouts.nSize == 0 )
+            Counter += Res_NodeDeref_rec( pFanin );
+    }
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [References the node's MFFC.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_NodeRef_rec( Abc_Obj_t * pNode )
+{
+    Abc_Obj_t * pFanin;
+    int i, Counter = 1;
+    if ( Abc_ObjIsCi(pNode) )
+        return 0;
+    Abc_ObjForEachFanin( pNode, pFanin, i )
+    {
+        if ( pFanin->vFanouts.nSize++ == 0 )
+            Counter += Res_NodeRef_rec( pFanin );
+    }
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Labels MFFC of the node with the current trav ID.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_WinVisitMffc( Abc_Obj_t * pNode )
+{
+    int Count1, Count2;
+    assert( Abc_ObjIsNode(pNode) );
+    // dereference the node (mark with the current trav ID)
+    Count1 = Res_NodeDeref_rec( pNode );
+    // reference it back
+    Count2 = Res_NodeRef_rec( pNode );
+    assert( Count1 == Count2 );
+    return Count1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/resFilter.c b/src/opt/res/resFilter.c
new file mode 100644
index 00000000..f2ca41d3
--- /dev/null
+++ b/src/opt/res/resFilter.c
@@ -0,0 +1,434 @@
+/**CFile****************************************************************
+
+  FileName    [resFilter.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Filtering resubstitution candidates.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resFilter.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static unsigned * Res_FilterCollectFaninInfo( Res_Win_t * pWin, Res_Sim_t * pSim, unsigned uMask );
+static int        Res_FilterCriticalFanin( Abc_Obj_t * pNode );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Finds sets of feasible candidates.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+ 
+***********************************************************************/
+int Res_FilterCandidates( Res_Win_t * pWin, Abc_Ntk_t * pAig, Res_Sim_t * pSim, Vec_Vec_t * vResubs, Vec_Vec_t * vResubsW, int nFaninsMax, int fArea )
+{
+    Abc_Obj_t * pFanin, * pFanin2, * pFaninTemp;
+    unsigned * pInfo, * pInfoDiv, * pInfoDiv2;
+    int Counter, RetValue, i, i2, d, d2, iDiv, iDiv2, k;
+
+    // check that the info the node is one
+    pInfo = Vec_PtrEntry( pSim->vOuts, 1 );
+    RetValue = Abc_InfoIsOne( pInfo, pSim->nWordsOut );
+    if ( RetValue == 0 )
+    {
+//        printf( "Failed 1!\n" );
+        return 0;
+    }
+
+    // collect the fanin info
+    pInfo = Res_FilterCollectFaninInfo( pWin, pSim, ~0 );
+    RetValue = Abc_InfoIsOne( pInfo, pSim->nWordsOut );
+    if ( RetValue == 0 )
+    {
+//        printf( "Failed 2!\n" );
+        return 0;
+    }
+
+    // try removing each fanin
+//    printf( "Fanins: " );
+    Counter = 0;
+    Vec_VecClear( vResubs );
+    Vec_VecClear( vResubsW );
+    Abc_ObjForEachFanin( pWin->pNode, pFanin, i )
+    {
+        if ( fArea && Abc_ObjFanoutNum(pFanin) > 1 )
+            continue;
+        // get simulation info without this fanin
+        pInfo = Res_FilterCollectFaninInfo( pWin, pSim, ~(1 << i) );
+        RetValue = Abc_InfoIsOne( pInfo, pSim->nWordsOut );
+        if ( RetValue )
+        {
+//            printf( "Node %4d. Candidate fanin %4d.\n", pWin->pNode->Id, pFanin->Id );
+            // collect the nodes
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,0) );
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,1) );
+            Abc_ObjForEachFanin( pWin->pNode, pFaninTemp, k )
+            {
+                if ( k != i )
+                {
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,2+k) );
+                    Vec_VecPush( vResubsW, Counter, pFaninTemp );
+                }
+            }
+            Counter++;
+            if ( Counter == Vec_VecSize(vResubs) )
+                return Counter;    
+        }
+    }
+
+    // try replacing each critical fanin by a non-critical fanin
+    Abc_ObjForEachFanin( pWin->pNode, pFanin, i )
+    {
+        if ( Abc_ObjFanoutNum(pFanin) > 1 )
+            continue;
+        // get simulation info without this fanin
+        pInfo = Res_FilterCollectFaninInfo( pWin, pSim, ~(1 << i) );
+        // go over the set of divisors
+        for ( d = Abc_ObjFaninNum(pWin->pNode) + 2; d < Abc_NtkPoNum(pAig); d++ )
+        {
+            pInfoDiv = Vec_PtrEntry( pSim->vOuts, d );
+            iDiv = d - (Abc_ObjFaninNum(pWin->pNode) + 2);
+            if ( !Abc_InfoIsOrOne( pInfo, pInfoDiv, pSim->nWordsOut ) )
+                continue;
+            // collect the nodes
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,0) );
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,1) );
+            // collect the remaning fanins and the divisor
+            Abc_ObjForEachFanin( pWin->pNode, pFaninTemp, k )
+            {
+                if ( k != i )
+                {
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,2+k) );
+                    Vec_VecPush( vResubsW, Counter, pFaninTemp );
+                }
+            }
+            // collect the divisor
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,d) );
+            Vec_VecPush( vResubsW, Counter, Vec_PtrEntry(pWin->vDivs, iDiv) );
+            Counter++;
+            if ( Counter == Vec_VecSize(vResubs) )
+                return Counter;           
+        }
+    }
+
+    // consider the case when two fanins can be added instead of one
+    if ( Abc_ObjFaninNum(pWin->pNode) < nFaninsMax )
+    {
+        // try to replace each critical fanin by two non-critical fanins
+        Abc_ObjForEachFanin( pWin->pNode, pFanin, i )
+        {
+            if ( Abc_ObjFanoutNum(pFanin) > 1 )
+                continue;
+            // get simulation info without this fanin
+            pInfo = Res_FilterCollectFaninInfo( pWin, pSim, ~(1 << i) );
+            // go over the set of divisors
+            for ( d = Abc_ObjFaninNum(pWin->pNode) + 2; d < Abc_NtkPoNum(pAig); d++ )
+            {
+                pInfoDiv = Vec_PtrEntry( pSim->vOuts, d );
+                iDiv = d - (Abc_ObjFaninNum(pWin->pNode) + 2);
+                // go through the second divisor
+                for ( d2 = d + 1; d2 < Abc_NtkPoNum(pAig); d2++ )
+                {
+                    pInfoDiv2 = Vec_PtrEntry( pSim->vOuts, d2 );
+                    iDiv2 = d2 - (Abc_ObjFaninNum(pWin->pNode) + 2);
+                    if ( !Abc_InfoIsOrOne3( pInfo, pInfoDiv, pInfoDiv2, pSim->nWordsOut ) )
+                        continue;
+                    // collect the nodes
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,0) );
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,1) );
+                    // collect the remaning fanins and the divisor
+                    Abc_ObjForEachFanin( pWin->pNode, pFaninTemp, k )
+                    {
+                        if ( k != i )
+                        {
+                            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,2+k) );
+                            Vec_VecPush( vResubsW, Counter, pFaninTemp );
+                        }
+                    }
+                    // collect the divisor
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,d) );
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,d2) );
+                    Vec_VecPush( vResubsW, Counter, Vec_PtrEntry(pWin->vDivs, iDiv) );
+                    Vec_VecPush( vResubsW, Counter, Vec_PtrEntry(pWin->vDivs, iDiv2) );
+                    Counter++;
+                    if ( Counter == Vec_VecSize(vResubs) )
+                        return Counter;           
+                }
+            }
+        }
+    }
+
+    // try to replace two nets by one
+    if ( !fArea )
+    {
+        Abc_ObjForEachFanin( pWin->pNode, pFanin, i )
+        {
+            for ( i2 = i + 1; i2 < Abc_ObjFaninNum(pWin->pNode); i2++ )
+            {
+                pFanin2 = Abc_ObjFanin(pWin->pNode, i2);
+                // get simulation info without these fanins
+                pInfo = Res_FilterCollectFaninInfo( pWin, pSim, (~(1 << i)) & (~(1 << i2)) );
+                // go over the set of divisors
+                for ( d = Abc_ObjFaninNum(pWin->pNode) + 2; d < Abc_NtkPoNum(pAig); d++ )
+                {
+                    pInfoDiv = Vec_PtrEntry( pSim->vOuts, d );
+                    iDiv = d - (Abc_ObjFaninNum(pWin->pNode) + 2);
+                    if ( !Abc_InfoIsOrOne( pInfo, pInfoDiv, pSim->nWordsOut ) )
+                        continue;
+                    // collect the nodes
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,0) );
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,1) );
+                    // collect the remaning fanins and the divisor
+                    Abc_ObjForEachFanin( pWin->pNode, pFaninTemp, k )
+                    {
+                        if ( k != i && k != i2 )
+                        {
+                            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,2+k) );
+                            Vec_VecPush( vResubsW, Counter, pFaninTemp );
+                        }
+                    }
+                    // collect the divisor
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,d) );
+                    Vec_VecPush( vResubsW, Counter, Vec_PtrEntry(pWin->vDivs, iDiv) );
+                    Counter++;
+                    if ( Counter == Vec_VecSize(vResubs) )
+                        return Counter;           
+                }
+            }
+        }
+    }
+    return Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Finds sets of feasible candidates.]
+
+  Description [This procedure is a special case of the above.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_FilterCandidatesArea( Res_Win_t * pWin, Abc_Ntk_t * pAig, Res_Sim_t * pSim, Vec_Vec_t * vResubs, Vec_Vec_t * vResubsW, int nFaninsMax )
+{
+    Abc_Obj_t * pFanin;
+    unsigned * pInfo, * pInfoDiv, * pInfoDiv2;
+    int Counter, RetValue, d, d2, k, iDiv, iDiv2, iBest;
+
+    // check that the info the node is one
+    pInfo = Vec_PtrEntry( pSim->vOuts, 1 );
+    RetValue = Abc_InfoIsOne( pInfo, pSim->nWordsOut );
+    if ( RetValue == 0 )
+    {
+//        printf( "Failed 1!\n" );
+        return 0;
+    }
+
+    // collect the fanin info
+    pInfo = Res_FilterCollectFaninInfo( pWin, pSim, ~0 );
+    RetValue = Abc_InfoIsOne( pInfo, pSim->nWordsOut );
+    if ( RetValue == 0 )
+    {
+//        printf( "Failed 2!\n" );
+        return 0;
+    }
+
+    // try removing fanins
+//    printf( "Fanins: " );
+    Counter = 0;
+    Vec_VecClear( vResubs );
+    Vec_VecClear( vResubsW );
+    // get the best fanins
+    iBest = Res_FilterCriticalFanin( pWin->pNode );
+    if ( iBest == -1 )
+        return 0;
+
+    // get the info without the critical fanin
+    pInfo = Res_FilterCollectFaninInfo( pWin, pSim, ~(1 << iBest) );
+    RetValue = Abc_InfoIsOne( pInfo, pSim->nWordsOut );
+    if ( RetValue )
+    {
+//        printf( "Can be done without one!\n" );
+        // collect the nodes
+        Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,0) );
+        Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,1) );
+        Abc_ObjForEachFanin( pWin->pNode, pFanin, k )
+        {
+            if ( k != iBest )
+            {
+                Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,2+k) );
+                Vec_VecPush( vResubsW, Counter, pFanin );
+            }
+        }
+        Counter++;
+//        printf( "*" );
+        return Counter;
+    }
+
+    // go through the divisors
+    for ( d = Abc_ObjFaninNum(pWin->pNode) + 2; d < Abc_NtkPoNum(pAig); d++ )
+    {
+        pInfoDiv = Vec_PtrEntry( pSim->vOuts, d );
+        iDiv = d - (Abc_ObjFaninNum(pWin->pNode) + 2);
+        if ( !Abc_InfoIsOrOne( pInfo, pInfoDiv, pSim->nWordsOut ) )
+            continue;
+//if ( Abc_ObjLevel(pWin->pNode) <= Abc_ObjLevel( Vec_PtrEntry(pWin->vDivs, iDiv) ) )
+//    printf( "Node level = %d. Divisor level = %d.\n", Abc_ObjLevel(pWin->pNode), Abc_ObjLevel( Vec_PtrEntry(pWin->vDivs, iDiv) ) );
+        // collect the nodes
+        Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,0) );
+        Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,1) );
+        // collect the remaning fanins and the divisor
+        Abc_ObjForEachFanin( pWin->pNode, pFanin, k )
+        {
+            if ( k != iBest )
+            {
+                Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,2+k) );
+                Vec_VecPush( vResubsW, Counter, pFanin );
+            }
+        }
+        // collect the divisor
+        Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,d) );
+        Vec_VecPush( vResubsW, Counter, Vec_PtrEntry(pWin->vDivs, iDiv) );
+        Counter++;
+
+        if ( Counter == Vec_VecSize(vResubs) )
+            break;            
+    }
+
+    if ( Counter > 0 || Abc_ObjFaninNum(pWin->pNode) >= nFaninsMax )
+        return Counter;
+
+    // try to find the node pairs
+    for ( d = Abc_ObjFaninNum(pWin->pNode) + 2; d < Abc_NtkPoNum(pAig); d++ )
+    {
+        pInfoDiv = Vec_PtrEntry( pSim->vOuts, d );
+        iDiv = d - (Abc_ObjFaninNum(pWin->pNode) + 2);
+        // go through the second divisor
+        for ( d2 = d + 1; d2 < Abc_NtkPoNum(pAig); d2++ )
+        {
+            pInfoDiv2 = Vec_PtrEntry( pSim->vOuts, d2 );
+            iDiv2 = d2 - (Abc_ObjFaninNum(pWin->pNode) + 2);
+
+            if ( !Abc_InfoIsOrOne3( pInfo, pInfoDiv, pInfoDiv2, pSim->nWordsOut ) )
+                continue;
+            // collect the nodes
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,0) );
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,1) );
+            // collect the remaning fanins and the divisor
+            Abc_ObjForEachFanin( pWin->pNode, pFanin, k )
+            {
+                if ( k != iBest )
+                {
+                    Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,2+k) );
+                    Vec_VecPush( vResubsW, Counter, pFanin );
+                }
+            }
+            // collect the divisor
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,d) );
+            Vec_VecPush( vResubs, Counter, Abc_NtkPo(pAig,d2) );
+            Vec_VecPush( vResubsW, Counter, Vec_PtrEntry(pWin->vDivs, iDiv) );
+            Vec_VecPush( vResubsW, Counter, Vec_PtrEntry(pWin->vDivs, iDiv2) );
+            Counter++;
+
+            if ( Counter == Vec_VecSize(vResubs) )
+                break;            
+        }
+        if ( Counter == Vec_VecSize(vResubs) )
+            break;            
+    }
+    return Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Finds sets of feasible candidates.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned * Res_FilterCollectFaninInfo( Res_Win_t * pWin, Res_Sim_t * pSim, unsigned uMask )
+{
+    Abc_Obj_t * pFanin;
+    unsigned * pInfo;
+    int i;
+    pInfo = Vec_PtrEntry( pSim->vOuts, 0 );
+    Abc_InfoClear( pInfo, pSim->nWordsOut );
+    Abc_ObjForEachFanin( pWin->pNode, pFanin, i )
+    {
+        if ( uMask & (1 << i) )
+            Abc_InfoOr( pInfo, Vec_PtrEntry(pSim->vOuts, 2+i), pSim->nWordsOut );
+    }
+    return pInfo;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the index of the most critical fanin.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_FilterCriticalFanin( Abc_Obj_t * pNode )
+{
+    Abc_Obj_t * pFanin;
+    int i, iBest = -1, CostMax = 0, CostCur;
+    Abc_ObjForEachFanin( pNode, pFanin, i )
+    {
+        if ( !Abc_ObjIsNode(pFanin) )
+            continue;
+        if ( Abc_ObjFanoutNum(pFanin) > 1 )
+            continue;
+        CostCur = Res_WinVisitMffc( pFanin );
+        if ( CostMax < CostCur )
+        {
+            CostMax = CostCur;
+            iBest = i;
+        }
+    }
+//    if ( CostMax > 0 )
+//        printf( "<%d>", CostMax );
+    return iBest;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/resInt.h b/src/opt/res/resInt.h
new file mode 100644
index 00000000..5aae46cc
--- /dev/null
+++ b/src/opt/res/resInt.h
@@ -0,0 +1,137 @@
+/**CFile****************************************************************
+
+  FileName    [resInt.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Internal declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resInt.h,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __RES_INT_H__
+#define __RES_INT_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "res.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Res_Win_t_ Res_Win_t;
+struct Res_Win_t_
+{
+    // windowing parameters
+    Abc_Obj_t *      pNode;        // the node in the center
+    int              nWinTfiMax;   // the fanin levels
+    int              nWinTfoMax;   // the fanout levels
+    int              nLevDivMax;   // the maximum divisor level
+    // internal windowing parameters
+    int              nFanoutLimit; // the limit on the fanout count of a TFO node (if more, the node is treated as a root)
+    int              nLevTfiMinus; // the number of additional levels to search from TFO below the level of leaves
+    // derived windowing parameters
+    int              nLevLeafMin;  // the minimum level of a leaf
+    int              nLevTravMin;  // the minimum level to search from TFO
+    int              nDivsPlus;    // the number of additional divisors
+    // the window data
+    Vec_Ptr_t *      vRoots;       // outputs of the window
+    Vec_Ptr_t *      vLeaves;      // inputs of the window
+    Vec_Ptr_t *      vBranches;    // side nodes of the window
+    Vec_Ptr_t *      vNodes;       // internal nodes of the window
+    Vec_Ptr_t *      vDivs;        // candidate divisors of the node
+    // temporary data
+    Vec_Vec_t *      vMatrix;      // TFI nodes below the given node
+};
+
+typedef struct Res_Sim_t_ Res_Sim_t;
+struct Res_Sim_t_
+{
+    Abc_Ntk_t *      pAig;         // AIG for simulation
+    int              nTruePis;     // the number of true PIs of the window
+    int              fConst0;      // the node can be replaced by constant 0
+    int              fConst1;      // the node can be replaced by constant 0
+    // simulation parameters
+    int              nWords;       // the number of simulation words
+    int              nPats;        // the number of patterns
+    int              nWordsIn;     // the number of simulation words in the input patterns
+    int              nPatsIn;      // the number of patterns in the input patterns 
+    int              nBytesIn;     // the number of bytes in the input patterns
+    int              nWordsOut;    // the number of simulation words in the output patterns
+    int              nPatsOut;     // the number of patterns in the output patterns 
+    // simulation info
+    Vec_Ptr_t *      vPats;        // input simulation patterns
+    Vec_Ptr_t *      vPats0;       // input simulation patterns
+    Vec_Ptr_t *      vPats1;       // input simulation patterns
+    Vec_Ptr_t *      vOuts;        // output simulation info
+    int              nPats0;       // the number of 0-patterns accumulated
+    int              nPats1;       // the number of 1-patterns accumulated
+    // resub candidates
+    Vec_Vec_t *      vCands;       // resubstitution candidates
+    // statistics
+    int              timeSat;
+};
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== resDivs.c ==========================================================*/
+extern void          Res_WinDivisors( Res_Win_t * p, int nLevDivMax );
+extern void          Res_WinSweepLeafTfo_rec( Abc_Obj_t * pObj, int nLevelLimit );
+extern int           Res_WinVisitMffc( Abc_Obj_t * pNode );
+/*=== resFilter.c ==========================================================*/
+extern int           Res_FilterCandidates( Res_Win_t * pWin, Abc_Ntk_t * pAig, Res_Sim_t * pSim, Vec_Vec_t * vResubs, Vec_Vec_t * vResubsW, int nFaninsMax, int fArea );
+extern int           Res_FilterCandidatesArea( Res_Win_t * pWin, Abc_Ntk_t * pAig, Res_Sim_t * pSim, Vec_Vec_t * vResubs, Vec_Vec_t * vResubsW, int nFaninsMax );
+/*=== resSat.c ==========================================================*/
+extern void *        Res_SatProveUnsat( Abc_Ntk_t * pAig, Vec_Ptr_t * vFanins );
+extern int           Res_SatSimulate( Res_Sim_t * p, int nPats, int fOnSet );
+/*=== resSim.c ==========================================================*/
+extern Res_Sim_t *   Res_SimAlloc( int nWords );
+extern void          Res_SimFree( Res_Sim_t * p );
+extern int           Res_SimPrepare( Res_Sim_t * p, Abc_Ntk_t * pAig, int nTruePis, int fVerbose );
+/*=== resStrash.c ==========================================================*/
+extern Abc_Ntk_t *   Res_WndStrash( Res_Win_t * p );
+/*=== resWnd.c ==========================================================*/
+extern void          Res_UpdateNetwork( Abc_Obj_t * pObj, Vec_Ptr_t * vFanins, Hop_Obj_t * pFunc, Vec_Vec_t * vLevels );
+/*=== resWnd.c ==========================================================*/
+extern Res_Win_t *   Res_WinAlloc();
+extern void          Res_WinFree( Res_Win_t * p );
+extern int           Res_WinIsTrivial( Res_Win_t * p );
+extern int           Res_WinCompute( Abc_Obj_t * pNode, int nWinTfiMax, int nWinTfoMax, Res_Win_t * p );
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/res/resSat.c b/src/opt/res/resSat.c
new file mode 100644
index 00000000..dd0e7a23
--- /dev/null
+++ b/src/opt/res/resSat.c
@@ -0,0 +1,407 @@
+/**CFile****************************************************************
+
+  FileName    [resSat.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Interface with the SAT solver.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resSat.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+#include "hop.h"
+#include "satSolver.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+extern int Res_SatAddConst1( sat_solver * pSat, int iVar, int fCompl );
+extern int Res_SatAddEqual( sat_solver * pSat, int iVar0, int iVar1, int fCompl );
+extern int Res_SatAddAnd( sat_solver * pSat, int iVar, int iVar0, int iVar1, int fCompl0, int fCompl1 );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Loads AIG into the SAT solver for checking resubstitution.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void * Res_SatProveUnsat( Abc_Ntk_t * pAig, Vec_Ptr_t * vFanins )
+{
+    void * pCnf = NULL;
+    sat_solver * pSat;
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pObj;
+    int i, nNodes, status;
+
+    // make sure fanins contain POs of the AIG
+    pObj = Vec_PtrEntry( vFanins, 0 );
+    assert( pObj->pNtk == pAig && Abc_ObjIsPo(pObj) );
+
+    // collect reachable nodes
+    vNodes = Abc_NtkDfsNodes( pAig, (Abc_Obj_t **)vFanins->pArray, vFanins->nSize );
+
+    // assign unique numbers to each node
+    nNodes = 0;
+    Abc_AigConst1(pAig)->pCopy = (void *)nNodes++;
+    Abc_NtkForEachPi( pAig, pObj, i )
+        pObj->pCopy = (void *)nNodes++;
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        pObj->pCopy = (void *)nNodes++;
+    Vec_PtrForEachEntry( vFanins, pObj, i ) // useful POs
+        pObj->pCopy = (void *)nNodes++;
+
+    // start the solver
+    pSat = sat_solver_new();
+    sat_solver_store_alloc( pSat );
+
+    // add clause for the constant node
+    Res_SatAddConst1( pSat, (int)Abc_AigConst1(pAig)->pCopy, 0 );
+    // add clauses for AND gates
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        Res_SatAddAnd( pSat, (int)pObj->pCopy, 
+            (int)Abc_ObjFanin0(pObj)->pCopy, (int)Abc_ObjFanin1(pObj)->pCopy, Abc_ObjFaninC0(pObj), Abc_ObjFaninC1(pObj) );
+    Vec_PtrFree( vNodes );
+    // add clauses for POs
+    Vec_PtrForEachEntry( vFanins, pObj, i )
+        Res_SatAddEqual( pSat, (int)pObj->pCopy, 
+            (int)Abc_ObjFanin0(pObj)->pCopy, Abc_ObjFaninC0(pObj) );
+    // add trivial clauses
+    pObj = Vec_PtrEntry(vFanins, 0);
+    Res_SatAddConst1( pSat, (int)pObj->pCopy, 0 ); // care-set
+    pObj = Vec_PtrEntry(vFanins, 1);
+    Res_SatAddConst1( pSat, (int)pObj->pCopy, 0 ); // on-set
+
+    // bookmark the clauses of A
+    sat_solver_store_mark_clauses_a( pSat );
+
+    // duplicate the clauses
+    pObj = Vec_PtrEntry(vFanins, 1);
+    Sat_SolverDoubleClauses( pSat, (int)pObj->pCopy );
+    // add the equality constraints
+    Vec_PtrForEachEntryStart( vFanins, pObj, i, 2 )
+        Res_SatAddEqual( pSat, (int)pObj->pCopy, ((int)pObj->pCopy) + nNodes, 0 );
+
+    // bookmark the roots
+    sat_solver_store_mark_roots( pSat );
+
+    // solve the problem
+    status = sat_solver_solve( pSat, NULL, NULL, (sint64)10000, (sint64)0, (sint64)0, (sint64)0 );
+    if ( status == l_False )
+    {
+        pCnf = sat_solver_store_release( pSat );
+//        printf( "unsat\n" );
+    }
+    else if ( status == l_True )
+    {
+//        printf( "sat\n" );
+    }
+    else
+    {
+//        printf( "undef\n" );
+    }
+    sat_solver_delete( pSat );
+    return pCnf;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Loads AIG into the SAT solver for constrained simulation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void * Res_SatSimulateConstr( Abc_Ntk_t * pAig, int fOnSet )
+{
+    sat_solver * pSat;
+    Vec_Ptr_t * vFanins;
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pObj;
+    int i, nNodes;
+
+    // start the array
+    vFanins = Vec_PtrAlloc( 2 );
+    pObj = Abc_NtkPo( pAig, 0 );
+    Vec_PtrPush( vFanins, pObj );
+    pObj = Abc_NtkPo( pAig, 1 );
+    Vec_PtrPush( vFanins, pObj );
+
+    // collect reachable nodes
+    vNodes = Abc_NtkDfsNodes( pAig, (Abc_Obj_t **)vFanins->pArray, vFanins->nSize );
+
+    // assign unique numbers to each node
+    nNodes = 0;
+    Abc_AigConst1(pAig)->pCopy = (void *)nNodes++;
+    Abc_NtkForEachPi( pAig, pObj, i )
+        pObj->pCopy = (void *)nNodes++;
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        pObj->pCopy = (void *)nNodes++;
+    Vec_PtrForEachEntry( vFanins, pObj, i ) // useful POs
+        pObj->pCopy = (void *)nNodes++;
+
+    // start the solver
+    pSat = sat_solver_new();
+
+    // add clause for the constant node
+    Res_SatAddConst1( pSat, (int)Abc_AigConst1(pAig)->pCopy, 0 );
+    // add clauses for AND gates
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        Res_SatAddAnd( pSat, (int)pObj->pCopy, 
+            (int)Abc_ObjFanin0(pObj)->pCopy, (int)Abc_ObjFanin1(pObj)->pCopy, Abc_ObjFaninC0(pObj), Abc_ObjFaninC1(pObj) );
+    Vec_PtrFree( vNodes );
+    // add clauses for the first PO
+    pObj = Abc_NtkPo( pAig, 0 );
+    Res_SatAddEqual( pSat, (int)pObj->pCopy, 
+        (int)Abc_ObjFanin0(pObj)->pCopy, Abc_ObjFaninC0(pObj) );
+    // add clauses for the second PO
+    pObj = Abc_NtkPo( pAig, 1 );
+    Res_SatAddEqual( pSat, (int)pObj->pCopy, 
+        (int)Abc_ObjFanin0(pObj)->pCopy, Abc_ObjFaninC0(pObj) );
+
+    // add trivial clauses
+    pObj = Abc_NtkPo( pAig, 0 );
+    Res_SatAddConst1( pSat, (int)pObj->pCopy, 0 ); // care-set
+
+    pObj = Abc_NtkPo( pAig, 1 );
+    Res_SatAddConst1( pSat, (int)pObj->pCopy, !fOnSet ); // on-set
+
+    Vec_PtrFree( vFanins );
+    return pSat;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Loads AIG into the SAT solver for constrained simulation.]
+
+  Description [Returns 1 if the required number of patterns are found. 
+  Returns 0 if the solver ran out of time or proved a constant. 
+  In the latter, case one of the flags, fConst0 or fConst1, are set to 1.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_SatSimulate( Res_Sim_t * p, int nPatsLimit, int fOnSet )
+{
+    Vec_Int_t * vLits;
+    Vec_Ptr_t * vPats;
+    sat_solver * pSat;
+    int RetValue, i, k, value, status, Lit, Var, iPat;
+    int clk = clock();
+
+//printf( "Looking for %s:  ", fOnSet? "onset " : "offset" );
+
+    // decide what problem should be solved
+    Lit = toLitCond( (int)Abc_NtkPo(p->pAig,1)->pCopy, !fOnSet );
+    if ( fOnSet )
+    {
+        iPat = p->nPats1;
+        vPats = p->vPats1;
+    }
+    else
+    {
+        iPat = p->nPats0;
+        vPats = p->vPats0;
+    }
+    assert( iPat < nPatsLimit );
+
+    // derive the SAT solver
+    pSat = Res_SatSimulateConstr( p->pAig, fOnSet );
+    pSat->fSkipSimplify = 1;
+    status = sat_solver_simplify( pSat );
+    if ( status == 0 )
+    {
+        if ( iPat == 0 )
+        {
+//            if ( fOnSet )
+//                p->fConst0 = 1;
+//            else
+//                p->fConst1 = 1;
+            RetValue = 0;
+        }
+        goto finish;
+    }
+ 
+    // enumerate through the SAT assignments
+    RetValue = 1;
+    vLits = Vec_IntAlloc( 32 );
+    for ( k = iPat; k < nPatsLimit; k++ )
+    {
+        // solve with the assumption
+//        status = sat_solver_solve( pSat, &Lit, &Lit + 1, (sint64)10000, (sint64)0, (sint64)0, (sint64)0 );
+        status = sat_solver_solve( pSat, NULL, NULL, (sint64)10000, (sint64)0, (sint64)0, (sint64)0 );
+        if ( status == l_False )
+        {
+//printf( "Const %d\n", !fOnSet );
+            if ( k == 0 )
+            {
+                if ( fOnSet )
+                    p->fConst0 = 1;
+                else
+                    p->fConst1 = 1;
+                RetValue = 0;
+            }
+            break;
+        }
+        else if ( status == l_True )
+        {
+            // save the pattern
+            Vec_IntClear( vLits );
+            for ( i = 0; i < p->nTruePis; i++ )
+            {
+                Var = (int)Abc_NtkPi(p->pAig,i)->pCopy;
+                value = (int)(pSat->model.ptr[Var] == l_True);
+                if ( value )
+                    Abc_InfoSetBit( Vec_PtrEntry(vPats, i), k );
+                Lit = toLitCond( Var, value );
+                Vec_IntPush( vLits, Lit );
+//                printf( "%d", value );
+            }
+//            printf( "\n" );
+
+            status = sat_solver_addclause( pSat, Vec_IntArray(vLits), Vec_IntArray(vLits) + Vec_IntSize(vLits) );
+            if ( status == 0 )
+            {
+                k++;
+                RetValue = 1; 
+                break;
+            }
+        }
+        else
+        {
+//printf( "Undecided\n" );
+            if ( k == 0 )
+                RetValue = 0;
+            else
+                RetValue = 1; 
+            break;
+        }
+    }
+    Vec_IntFree( vLits );
+//printf( "Found %d patterns\n", k - iPat );
+
+    // set the new number of patterns
+    if ( fOnSet )
+        p->nPats1 = k;
+    else
+        p->nPats0 = k;
+
+finish:
+
+    sat_solver_delete( pSat );
+p->timeSat += clock() - clk;
+    return RetValue;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Asserts equality of the variable to a constant.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_SatAddConst1( sat_solver * pSat, int iVar, int fCompl )
+{
+    lit Lit = toLitCond( iVar, fCompl );
+    if ( !sat_solver_addclause( pSat, &Lit, &Lit + 1 ) )
+        return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Asserts equality of two variables.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_SatAddEqual( sat_solver * pSat, int iVar0, int iVar1, int fCompl )
+{
+    lit Lits[2];
+
+    Lits[0] = toLitCond( iVar0, 0 );
+    Lits[1] = toLitCond( iVar1, !fCompl );
+    if ( !sat_solver_addclause( pSat, Lits, Lits + 2 ) )
+        return 0;
+
+    Lits[0] = toLitCond( iVar0, 1 );
+    Lits[1] = toLitCond( iVar1, fCompl );
+    if ( !sat_solver_addclause( pSat, Lits, Lits + 2 ) )
+        return 0;
+
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds constraints for the two-input AND-gate.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_SatAddAnd( sat_solver * pSat, int iVar, int iVar0, int iVar1, int fCompl0, int fCompl1 )
+{
+    lit Lits[3];
+
+    Lits[0] = toLitCond( iVar, 1 );
+    Lits[1] = toLitCond( iVar0, fCompl0 );
+    if ( !sat_solver_addclause( pSat, Lits, Lits + 2 ) )
+        return 0;
+
+    Lits[0] = toLitCond( iVar, 1 );
+    Lits[1] = toLitCond( iVar1, fCompl1 );
+    if ( !sat_solver_addclause( pSat, Lits, Lits + 2 ) )
+        return 0;
+
+    Lits[0] = toLitCond( iVar, 0 );
+    Lits[1] = toLitCond( iVar0, !fCompl0 );
+    Lits[2] = toLitCond( iVar1, !fCompl1 );
+    if ( !sat_solver_addclause( pSat, Lits, Lits + 3 ) )
+        return 0;
+
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/resSim.c b/src/opt/res/resSim.c
new file mode 100644
index 00000000..5c1dd2b6
--- /dev/null
+++ b/src/opt/res/resSim.c
@@ -0,0 +1,790 @@
+/**CFile****************************************************************
+
+  FileName    [resSim.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Simulation engine.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resSim.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocate simulation engine.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+ 
+***********************************************************************/
+Res_Sim_t * Res_SimAlloc( int nWords )
+{
+    Res_Sim_t * p;
+    p = ALLOC( Res_Sim_t, 1 );
+    memset( p, 0, sizeof(Res_Sim_t) );
+    // simulation parameters
+    p->nWords    = nWords;
+    p->nPats     = p->nWords * 8 * sizeof(unsigned);
+    p->nWordsIn  = p->nPats;
+    p->nBytesIn  = p->nPats * sizeof(unsigned);
+    p->nPatsIn   = p->nPats * 8 * sizeof(unsigned);
+    p->nWordsOut = p->nPats * p->nWords;
+    p->nPatsOut  = p->nPats * p->nPats;
+    // simulation info
+    p->vPats     = Vec_PtrAllocSimInfo( 1024, p->nWordsIn );
+    p->vPats0    = Vec_PtrAllocSimInfo( 128, p->nWords );
+    p->vPats1    = Vec_PtrAllocSimInfo( 128, p->nWords );
+    p->vOuts     = Vec_PtrAllocSimInfo( 128, p->nWordsOut );
+    // resub candidates
+    p->vCands    = Vec_VecStart( 16 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Allocate simulation engine.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimAdjust( Res_Sim_t * p, Abc_Ntk_t * pAig, int nTruePis )
+{
+    srand( 0xABC );
+
+    assert( Abc_NtkIsStrash(pAig) );
+    p->pAig = pAig;
+    p->nTruePis = nTruePis;
+    if ( Vec_PtrSize(p->vPats) < Abc_NtkObjNumMax(pAig)+1 )
+    {
+        Vec_PtrFree( p->vPats );
+        p->vPats = Vec_PtrAllocSimInfo( Abc_NtkObjNumMax(pAig)+1, p->nWordsIn );
+    }
+    if ( Vec_PtrSize(p->vPats0) < nTruePis )
+    {
+        Vec_PtrFree( p->vPats0 );
+        p->vPats0 = Vec_PtrAllocSimInfo( nTruePis, p->nWords );
+    }
+    if ( Vec_PtrSize(p->vPats1) < nTruePis )
+    {
+        Vec_PtrFree( p->vPats1 );
+        p->vPats1 = Vec_PtrAllocSimInfo( nTruePis, p->nWords );
+    }
+    if ( Vec_PtrSize(p->vOuts) < Abc_NtkPoNum(pAig) )
+    {
+        Vec_PtrFree( p->vOuts );
+        p->vOuts = Vec_PtrAllocSimInfo( Abc_NtkPoNum(pAig), p->nWordsOut );
+    }
+    // clean storage info for patterns
+    Abc_InfoClear( Vec_PtrEntry(p->vPats0,0), p->nWords * nTruePis );
+    Abc_InfoClear( Vec_PtrEntry(p->vPats1,0), p->nWords * nTruePis );
+    p->nPats0 = 0;
+    p->nPats1 = 0;
+    p->fConst0 = 0;
+    p->fConst1 = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Free simulation engine.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimFree( Res_Sim_t * p )
+{
+    Vec_PtrFree( p->vPats );
+    Vec_PtrFree( p->vPats0 );
+    Vec_PtrFree( p->vPats1 );
+    Vec_PtrFree( p->vOuts );
+    Vec_VecFree( p->vCands );
+    free( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Sets random PI simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_InfoRandomBytes( unsigned * p, int nWords ) 
+{ 
+    int i, Num; 
+    for ( i = nWords - 1; i >= 0; i-- ) 
+    { 
+        Num = rand(); 
+        p[i] = (Num & 1)? 0xff : 0;
+        p[i] = (p[i] << 8) | ((Num & 2)? 0xff : 0);
+        p[i] = (p[i] << 8) | ((Num & 4)? 0xff : 0);
+        p[i] = (p[i] << 8) | ((Num & 8)? 0xff : 0);
+    } 
+//    Extra_PrintBinary( stdout, p, 32 ); printf( "\n" );
+} 
+
+/**Function*************************************************************
+
+  Synopsis    [Sets random PI simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimSetRandomBytes( Res_Sim_t * p )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfo;
+    int i;
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        if ( i < p->nTruePis )
+            Abc_InfoRandomBytes( pInfo, p->nWordsIn );
+        else
+            Abc_InfoRandom( pInfo, p->nWordsIn );
+    }
+/*
+    // double-check that all are byte-patterns
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        if ( i == p->nTruePis )
+            break;
+        pInfoC = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+        for ( k = 0; k < p->nBytesIn; k++ )
+            assert( pInfoC[k] == 0 || pInfoC[k] == 0xff );
+    }
+*/
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets random PI simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimSetDerivedBytes( Res_Sim_t * p, int fUseWalk )
+{
+    Vec_Ptr_t * vPatsSource[2];
+    int nPatsSource[2];
+    Abc_Obj_t * pObj;
+    unsigned char * pInfo;
+    int i, k, z, s, nPats;
+
+    // set several random patterns
+    assert( p->nBytesIn % 32 == 0 );
+    nPats = p->nBytesIn/8;
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        if ( i == p->nTruePis )
+            break;
+        Abc_InfoRandomBytes( Vec_PtrEntry(p->vPats, pObj->Id), nPats/4 );
+    }
+
+    // set special patterns
+    if ( fUseWalk )
+    {
+        for ( z = 0; z < 2; z++ )
+        {
+            // set the zero pattern
+            Abc_NtkForEachPi( p->pAig, pObj, i )
+            {
+                if ( i == p->nTruePis )
+                    break;
+                pInfo = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+                pInfo[nPats] = z ? 0xff : 0;
+            }
+            if ( ++nPats == p->nBytesIn )
+                return;
+            // set the walking zero pattern
+            for ( k = 0; k < p->nTruePis; k++ )
+            {
+                Abc_NtkForEachPi( p->pAig, pObj, i )
+                {
+                    if ( i == p->nTruePis )
+                        break;
+                    pInfo = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+                    pInfo[nPats] = ((i == k) ^ z) ? 0xff : 0;
+                }
+                if ( ++nPats == p->nBytesIn )
+                    return;
+            }
+        }
+    }
+
+    // decide what patterns to set first
+    if ( p->nPats0 < p->nPats1 )
+    {
+        nPatsSource[0] = p->nPats0;
+        vPatsSource[0] = p->vPats0;
+        nPatsSource[1] = p->nPats1;
+        vPatsSource[1] = p->vPats1;
+    }
+    else
+    {
+        nPatsSource[0] = p->nPats1;
+        vPatsSource[0] = p->vPats1;
+        nPatsSource[1] = p->nPats0;
+        vPatsSource[1] = p->vPats0;
+    }
+    for ( z = 0; z < 2; z++ )
+    {
+        for ( s = nPatsSource[z] - 1; s >= 0; s-- )
+        {
+//            if ( s == 0 )
+//            printf( "Patterns:\n" );
+            // set the given source pattern
+            for ( k = 0; k < p->nTruePis; k++ )
+            {
+                Abc_NtkForEachPi( p->pAig, pObj, i )
+                {
+                    if ( i == p->nTruePis )
+                        break;
+                    pInfo = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+                    if ( (i == k) ^ Abc_InfoHasBit( Vec_PtrEntry(vPatsSource[z], i), s ) )
+                    {
+                        pInfo[nPats] = 0xff;
+//                        if ( s == 0 )
+//                        printf( "1" );
+                    }
+                    else
+                    {
+                        pInfo[nPats] = 0;
+//                        if ( s == 0 )
+//                        printf( "0" );
+                    }
+                }
+//                if ( s == 0 )
+//                printf( "\n" );
+                if ( ++nPats == p->nBytesIn )
+                    return;
+            }
+        }
+    }
+    // clean the rest
+    for ( z = nPats; z < p->nBytesIn; z++ )
+    {
+        Abc_NtkForEachPi( p->pAig, pObj, i )
+        {
+            if ( i == p->nTruePis )
+                break;
+            pInfo = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+            memset( pInfo + nPats, 0, p->nBytesIn - nPats );
+        }
+    }
+/*
+    // double-check that all are byte-patterns
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        if ( i == p->nTruePis )
+            break;
+        pInfo = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+        for ( k = 0; k < p->nBytesIn; k++ )
+            assert( pInfo[k] == 0 || pInfo[k] == 0xff );
+    }
+*/
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets given PI simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimSetGiven( Res_Sim_t * p, Vec_Ptr_t * vInfo )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfo, * pInfo2;
+    int i, w;
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        if ( i == p->nTruePis )
+            break;
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        pInfo2 = Vec_PtrEntry( vInfo, i );
+        for ( w = 0; w < p->nWords; w++ )
+            pInfo[w] = pInfo2[w];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPerformOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords )
+{
+    unsigned * pInfo, * pInfo1, * pInfo2;
+    int k, fComp1, fComp2;
+    // simulate the internal nodes
+    assert( Abc_ObjIsNode(pNode) );
+    pInfo  = Vec_PtrEntry(vSimInfo, pNode->Id);
+    pInfo1 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId0(pNode));
+    pInfo2 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId1(pNode));
+    fComp1 = Abc_ObjFaninC0(pNode);
+    fComp2 = Abc_ObjFaninC1(pNode);
+    if ( fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] = ~pInfo1[k] & ~pInfo2[k];
+    else if ( fComp1 && !fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] = ~pInfo1[k] &  pInfo2[k];
+    else if ( !fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] =  pInfo1[k] & ~pInfo2[k];
+    else // if ( fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] =  pInfo1[k] &  pInfo2[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one CO node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimTransferOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords )
+{
+    unsigned * pInfo, * pInfo1;
+    int k, fComp1;
+    // simulate the internal nodes
+    assert( Abc_ObjIsCo(pNode) );
+    pInfo  = Vec_PtrEntry(vSimInfo, pNode->Id);
+    pInfo1 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId0(pNode));
+    fComp1 = Abc_ObjFaninC0(pNode);
+    if ( fComp1 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] = ~pInfo1[k];
+    else 
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] =  pInfo1[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs one round of simulation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPerformRound( Res_Sim_t * p, int nWords )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    Abc_InfoFill( Vec_PtrEntry(p->vPats,0), nWords );
+    Abc_AigForEachAnd( p->pAig, pObj, i )
+        Res_SimPerformOne( pObj, p->vPats, nWords );
+    Abc_NtkForEachPo( p->pAig, pObj, i )
+        Res_SimTransferOne( pObj, p->vPats, nWords );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Pads the extra space with duplicated simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPadSimInfo( Vec_Ptr_t * vPats, int nPats, int nWords )
+{
+    unsigned * pInfo;
+    int i, w, iWords;
+    assert( nPats > 0 && nPats < nWords * 8 * (int) sizeof(unsigned) );
+    // pad the first word
+    if ( nPats < 8 * sizeof(unsigned) )
+    {
+        Vec_PtrForEachEntry( vPats, pInfo, i )
+            if ( pInfo[0] & 1 )
+                pInfo[0] |= ((~0) << nPats);
+        nPats = 8 * sizeof(unsigned);
+    }
+    // pad the empty words
+    iWords = nPats / (8 * sizeof(unsigned));
+    Vec_PtrForEachEntry( vPats, pInfo, i )
+    {
+        for ( w = iWords; w < nWords; w++ )
+            pInfo[w] = pInfo[0];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Duplicates the simulation info to fill the space.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimDeriveInfoReplicate( Res_Sim_t * p )
+{
+    unsigned * pInfo, * pInfo2;
+    Abc_Obj_t * pObj;
+    int i, j, w;
+    Abc_NtkForEachPo( p->pAig, pObj, i )
+    {
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        pInfo2 = Vec_PtrEntry( p->vOuts, i );
+        for ( j = 0; j < p->nPats; j++ )
+            for ( w = 0; w < p->nWords; w++ )
+                *pInfo2++ = pInfo[w];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Complement the simulation info if necessary.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimDeriveInfoComplement( Res_Sim_t * p )
+{
+    unsigned * pInfo, * pInfo2;
+    Abc_Obj_t * pObj;
+    int i, j, w;
+    Abc_NtkForEachPo( p->pAig, pObj, i )
+    {
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        pInfo2 = Vec_PtrEntry( p->vOuts, i );
+        for ( j = 0; j < p->nPats; j++, pInfo2 += p->nWords )
+            if ( Abc_InfoHasBit( pInfo, j ) )
+                for ( w = 0; w < p->nWords; w++ )
+                    pInfo2[w] = ~pInfo2[w];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints output patterns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPrintOutPatterns( Res_Sim_t * p, Abc_Ntk_t * pAig )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfo2;
+    int i;
+    Abc_NtkForEachPo( pAig, pObj, i )
+    {
+        pInfo2 = Vec_PtrEntry( p->vOuts, i );
+        Extra_PrintBinary( stdout, pInfo2, p->nPatsOut );
+        printf( "\n" );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints output patterns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPrintNodePatterns( Res_Sim_t * p, Abc_Ntk_t * pAig )
+{
+    unsigned * pInfo;
+    pInfo = Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 1)->Id );
+    Extra_PrintBinary( stdout, pInfo, p->nPats );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of patters of different type.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimCountResults( Res_Sim_t * p, int * pnDcs, int * pnOnes, int * pnZeros, int fVerbose )
+{
+    unsigned char * pInfoCare, * pInfoNode;
+    int i, nTotal = 0;
+    pInfoCare = (unsigned char *)Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 0)->Id );
+    pInfoNode = (unsigned char *)Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 1)->Id );
+    for ( i = 0; i < p->nBytesIn; i++ )
+    {
+        if ( !pInfoCare[i] )
+            (*pnDcs)++;
+        else if ( !pInfoNode[i] )
+            (*pnZeros)++;
+        else
+            (*pnOnes)++;
+    }
+    nTotal += *pnDcs;
+    nTotal += *pnZeros;
+    nTotal += *pnOnes;
+    if ( fVerbose )
+    {
+        printf( "Dc = %7.2f %%  ",  100.0*(*pnDcs)  /nTotal );
+        printf( "On = %7.2f %%  ",  100.0*(*pnOnes) /nTotal );
+        printf( "Off = %7.2f %%  ", 100.0*(*pnZeros)/nTotal );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of patters of different type.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimCollectPatterns( Res_Sim_t * p, int fVerbose )
+{
+    Abc_Obj_t * pObj;
+    unsigned char * pInfoCare, * pInfoNode, * pInfo;
+    int i, j;
+    pInfoCare = (unsigned char *)Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 0)->Id );
+    pInfoNode = (unsigned char *)Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 1)->Id );
+    for ( i = 0; i < p->nBytesIn; i++ )
+    {
+        // skip don't-care patterns
+        if ( !pInfoCare[i] )
+            continue;
+        // separate offset and onset patterns
+        assert( pInfoNode[i] == 0 || pInfoNode[i] == 0xff );
+        if ( !pInfoNode[i] )
+        {
+            if ( p->nPats0 >= p->nPats )
+                continue;
+            Abc_NtkForEachPi( p->pAig, pObj, j )
+            {
+                if ( j == p->nTruePis )
+                    break;
+                pInfo = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+                assert( pInfo[i] == 0 || pInfo[i] == 0xff );
+                if ( pInfo[i] )
+                    Abc_InfoSetBit( Vec_PtrEntry(p->vPats0, j), p->nPats0 );
+            }
+            p->nPats0++;
+        }
+        else
+        {
+            if ( p->nPats1 >= p->nPats )
+                continue;
+            Abc_NtkForEachPi( p->pAig, pObj, j )
+            {
+                if ( j == p->nTruePis )
+                    break;
+                pInfo = (unsigned char *)Vec_PtrEntry( p->vPats, pObj->Id );
+                assert( pInfo[i] == 0 || pInfo[i] == 0xff );
+                if ( pInfo[i] )
+                    Abc_InfoSetBit( Vec_PtrEntry(p->vPats1, j), p->nPats1 );
+            }
+            p->nPats1++;
+        }
+        if ( p->nPats0 >= p->nPats && p->nPats1 >= p->nPats )
+            break;
+    }
+    if ( fVerbose )
+    {
+        printf( "|  " );
+        printf( "On = %3d  ", p->nPats1 );
+        printf( "Off = %3d  ", p->nPats0 );
+        printf( "\n" );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies the last pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_SimVerifyValue( Res_Sim_t * p, int fOnSet )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfo, * pInfo2;
+    int i, value;
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        if ( i == p->nTruePis )
+            break;
+        if ( fOnSet )
+        {
+            pInfo2 = Vec_PtrEntry( p->vPats1, i );
+            value = Abc_InfoHasBit( pInfo2, p->nPats1 - 1 );
+        }
+        else
+        {
+            pInfo2 = Vec_PtrEntry( p->vPats0, i );
+            value = Abc_InfoHasBit( pInfo2, p->nPats0 - 1 );
+        }
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        pInfo[0] = value ? ~0 : 0;
+    }
+    Res_SimPerformRound( p, 1 );
+    pObj = Abc_NtkPo( p->pAig, 1 );
+    pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+    assert( pInfo[0] == 0 || pInfo[0] == ~0 );
+    return pInfo[0] > 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares simulation info for candidate filtering.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_SimPrepare( Res_Sim_t * p, Abc_Ntk_t * pAig, int nTruePis, int fVerbose )
+{
+    int i, nOnes = 0, nZeros = 0, nDcs = 0;
+    if ( fVerbose )
+        printf( "\n" );
+    // prepare the manager
+    Res_SimAdjust( p, pAig, nTruePis );
+    // estimate the number of patterns
+    Res_SimSetRandomBytes( p );
+    Res_SimPerformRound( p, p->nWordsIn );
+    Res_SimCountResults( p, &nDcs, &nOnes, &nZeros, fVerbose );
+    // collect the patterns
+    Res_SimCollectPatterns( p, fVerbose );
+    // add more patterns using constraint simulation
+    if ( p->nPats0 < 8 )
+    {
+        if ( !Res_SatSimulate( p, 16, 0 ) )
+            return p->fConst0 || p->fConst1;
+//            return 0;
+//        printf( "Value0 = %d\n", Res_SimVerifyValue( p, 0 ) );
+    }
+    if ( p->nPats1 < 8 )
+    {
+        if ( !Res_SatSimulate( p, 16, 1 ) )
+            return p->fConst0 || p->fConst1;
+//            return 0;
+//        printf( "Value1 = %d\n", Res_SimVerifyValue( p, 1 ) );
+    }
+    // generate additional patterns
+    for ( i = 0; i < 2; i++ )
+    {
+        if ( p->nPats0 > p->nPats*7/8 && p->nPats1 > p->nPats*7/8 )
+            break;
+        Res_SimSetDerivedBytes( p, i==0 );
+        Res_SimPerformRound( p, p->nWordsIn );
+        Res_SimCountResults( p, &nDcs, &nOnes, &nZeros, fVerbose );
+        Res_SimCollectPatterns( p, fVerbose );
+    }
+    // create bit-matrix info
+    if ( p->nPats0 < p->nPats )
+        Res_SimPadSimInfo( p->vPats0, p->nPats0, p->nWords );
+    if ( p->nPats1 < p->nPats )
+        Res_SimPadSimInfo( p->vPats1, p->nPats1, p->nWords );
+    // resimulate 0-patterns
+    Res_SimSetGiven( p, p->vPats0 );
+    Res_SimPerformRound( p, p->nWords );
+//Res_SimPrintNodePatterns( p, pAig );
+    Res_SimDeriveInfoReplicate( p );
+    // resimulate 1-patterns
+    Res_SimSetGiven( p, p->vPats1 );
+    Res_SimPerformRound( p, p->nWords );
+//Res_SimPrintNodePatterns( p, pAig );
+    Res_SimDeriveInfoComplement( p );
+    // print output patterns
+//    Res_SimPrintOutPatterns( p, pAig );
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/resSim_old.c b/src/opt/res/resSim_old.c
new file mode 100644
index 00000000..23ce29e4
--- /dev/null
+++ b/src/opt/res/resSim_old.c
@@ -0,0 +1,521 @@
+/**CFile****************************************************************
+
+  FileName    [resSim.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Simulation engine.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resSim.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocate simulation engine.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+ 
+***********************************************************************/
+Res_Sim_t * Res_SimAlloc( int nWords )
+{
+    Res_Sim_t * p;
+    p = ALLOC( Res_Sim_t, 1 );
+    memset( p, 0, sizeof(Res_Sim_t) );
+    // simulation parameters
+    p->nWords    = nWords;
+    p->nPats     = 8 * sizeof(unsigned) * p->nWords;
+    p->nWordsOut = p->nPats * p->nWords;
+    p->nPatsOut  = p->nPats * p->nPats;
+    // simulation info
+    p->vPats     = Vec_PtrAllocSimInfo( 1024, p->nWords );
+    p->vPats0    = Vec_PtrAllocSimInfo( 128,  p->nWords );
+    p->vPats1    = Vec_PtrAllocSimInfo( 128,  p->nWords );
+    p->vOuts     = Vec_PtrAllocSimInfo( 128,  p->nWordsOut );
+    // resub candidates
+    p->vCands    = Vec_VecStart( 16 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Allocate simulation engine.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimAdjust( Res_Sim_t * p, Abc_Ntk_t * pAig )
+{
+    srand( 0xABC );
+
+    assert( Abc_NtkIsStrash(pAig) );
+    p->pAig = pAig;
+    if ( Vec_PtrSize(p->vPats) < Abc_NtkObjNumMax(pAig)+1 )
+    {
+        Vec_PtrFree( p->vPats );
+        p->vPats = Vec_PtrAllocSimInfo( Abc_NtkObjNumMax(pAig)+1, p->nWords );
+    }
+    if ( Vec_PtrSize(p->vPats0) < Abc_NtkPiNum(pAig) )
+    {
+        Vec_PtrFree( p->vPats0 );
+        p->vPats0 = Vec_PtrAllocSimInfo( Abc_NtkPiNum(pAig), p->nWords );
+    }
+    if ( Vec_PtrSize(p->vPats1) < Abc_NtkPiNum(pAig) )
+    {
+        Vec_PtrFree( p->vPats1 );
+        p->vPats1 = Vec_PtrAllocSimInfo( Abc_NtkPiNum(pAig), p->nWords );
+    }
+    if ( Vec_PtrSize(p->vOuts) < Abc_NtkPoNum(pAig) )
+    {
+        Vec_PtrFree( p->vOuts );
+        p->vOuts = Vec_PtrAllocSimInfo( Abc_NtkPoNum(pAig), p->nWordsOut );
+    }
+    // clean storage info for patterns
+    Abc_InfoClear( Vec_PtrEntry(p->vPats0,0), p->nWords * Abc_NtkPiNum(pAig) );
+    Abc_InfoClear( Vec_PtrEntry(p->vPats1,0), p->nWords * Abc_NtkPiNum(pAig) );
+    p->nPats0 = 0;
+    p->nPats1 = 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Free simulation engine.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimFree( Res_Sim_t * p )
+{
+    Vec_PtrFree( p->vPats );
+    Vec_PtrFree( p->vPats0 );
+    Vec_PtrFree( p->vPats1 );
+    Vec_PtrFree( p->vOuts );
+    Vec_VecFree( p->vCands );
+    free( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Sets random PI simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimSetRandom( Res_Sim_t * p )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfo;
+    int i;
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        Abc_InfoRandom( pInfo, p->nWords );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets given PI simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimSetGiven( Res_Sim_t * p, Vec_Ptr_t * vInfo )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfo, * pInfo2;
+    int i, w;
+    Abc_NtkForEachPi( p->pAig, pObj, i )
+    {
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        pInfo2 = Vec_PtrEntry( vInfo, i );
+        for ( w = 0; w < p->nWords; w++ )
+            pInfo[w] = pInfo2[w];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPerformOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords )
+{
+    unsigned * pInfo, * pInfo1, * pInfo2;
+    int k, fComp1, fComp2;
+    // simulate the internal nodes
+    assert( Abc_ObjIsNode(pNode) );
+    pInfo  = Vec_PtrEntry(vSimInfo, pNode->Id);
+    pInfo1 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId0(pNode));
+    pInfo2 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId1(pNode));
+    fComp1 = Abc_ObjFaninC0(pNode);
+    fComp2 = Abc_ObjFaninC1(pNode);
+    if ( fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] = ~pInfo1[k] & ~pInfo2[k];
+    else if ( fComp1 && !fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] = ~pInfo1[k] &  pInfo2[k];
+    else if ( !fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] =  pInfo1[k] & ~pInfo2[k];
+    else // if ( fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] =  pInfo1[k] &  pInfo2[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one CO node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimTransferOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords )
+{
+    unsigned * pInfo, * pInfo1;
+    int k, fComp1;
+    // simulate the internal nodes
+    assert( Abc_ObjIsCo(pNode) );
+    pInfo  = Vec_PtrEntry(vSimInfo, pNode->Id);
+    pInfo1 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId0(pNode));
+    fComp1 = Abc_ObjFaninC0(pNode);
+    if ( fComp1 )
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] = ~pInfo1[k];
+    else 
+        for ( k = 0; k < nSimWords; k++ )
+            pInfo[k] =  pInfo1[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs one round of simulation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPerformRound( Res_Sim_t * p )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    Abc_InfoFill( Vec_PtrEntry(p->vPats,0), p->nWords );
+    Abc_AigForEachAnd( p->pAig, pObj, i )
+        Res_SimPerformOne( pObj, p->vPats, p->nWords );
+    Abc_NtkForEachPo( p->pAig, pObj, i )
+        Res_SimTransferOne( pObj, p->vPats, p->nWords );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Processes simulation patterns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimProcessPats( Res_Sim_t * p )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfoCare, * pInfoNode;
+    int i, j, nDcs = 0;
+    pInfoCare = Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 0)->Id );
+    pInfoNode = Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 1)->Id );
+    for ( i = 0; i < p->nPats; i++ )
+    {
+        // skip don't-care patterns
+        if ( !Abc_InfoHasBit(pInfoCare, i) )
+        {
+            nDcs++;
+            continue;
+        }
+        // separate offset and onset patterns
+        if ( !Abc_InfoHasBit(pInfoNode, i) )
+        {
+            if ( p->nPats0 >= p->nPats )
+                continue;
+            Abc_NtkForEachPi( p->pAig, pObj, j )
+                if ( Abc_InfoHasBit( Vec_PtrEntry(p->vPats, pObj->Id), i ) )
+                    Abc_InfoSetBit( Vec_PtrEntry(p->vPats0, j), p->nPats0 );
+            p->nPats0++;
+        }
+        else
+        {
+            if ( p->nPats1 >= p->nPats )
+                continue;
+            Abc_NtkForEachPi( p->pAig, pObj, j )
+                if ( Abc_InfoHasBit( Vec_PtrEntry(p->vPats, pObj->Id), i ) )
+                    Abc_InfoSetBit( Vec_PtrEntry(p->vPats1, j), p->nPats1 );
+            p->nPats1++;
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Pads the extra space with duplicated simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPadSimInfo( Vec_Ptr_t * vPats, int nPats, int nWords )
+{
+    unsigned * pInfo;
+    int i, w, iWords;
+    assert( nPats > 0 && nPats < nWords * 8 * (int) sizeof(unsigned) );
+    // pad the first word
+    if ( nPats < 8 * sizeof(unsigned) )
+    {
+        Vec_PtrForEachEntry( vPats, pInfo, i )
+            if ( pInfo[0] & 1 )
+                pInfo[0] |= ((~0) << nPats);
+        nPats = 8 * sizeof(unsigned);
+    }
+    // pad the empty words
+    iWords = nPats / (8 * sizeof(unsigned));
+    Vec_PtrForEachEntry( vPats, pInfo, i )
+    {
+        for ( w = iWords; w < nWords; w++ )
+            pInfo[w] = pInfo[0];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Duplicates the simulation info to fill the space.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimDeriveInfoReplicate( Res_Sim_t * p )
+{
+    unsigned * pInfo, * pInfo2;
+    Abc_Obj_t * pObj;
+    int i, j, w;
+    Abc_NtkForEachPo( p->pAig, pObj, i )
+    {
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        pInfo2 = Vec_PtrEntry( p->vOuts, i );
+        for ( j = 0; j < p->nPats; j++ )
+            for ( w = 0; w < p->nWords; w++ )
+                *pInfo2++ = pInfo[w];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Complement the simulation info if necessary.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimDeriveInfoComplement( Res_Sim_t * p )
+{
+    unsigned * pInfo, * pInfo2;
+    Abc_Obj_t * pObj;
+    int i, j, w;
+    Abc_NtkForEachPo( p->pAig, pObj, i )
+    {
+        pInfo = Vec_PtrEntry( p->vPats, pObj->Id );
+        pInfo2 = Vec_PtrEntry( p->vOuts, i );
+        for ( j = 0; j < p->nPats; j++, pInfo2 += p->nWords )
+            if ( Abc_InfoHasBit( pInfo, j ) )
+                for ( w = 0; w < p->nWords; w++ )
+                    pInfo2[w] = ~pInfo2[w];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Free simulation engine.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimReportOne( Res_Sim_t * p )
+{
+    unsigned * pInfoCare, * pInfoNode;
+    int i, nDcs, nOnes, nZeros;
+    pInfoCare = Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 0)->Id );
+    pInfoNode = Vec_PtrEntry( p->vPats, Abc_NtkPo(p->pAig, 1)->Id );
+    nDcs = nOnes = nZeros = 0;
+    for ( i = 0; i < p->nPats; i++ )
+    {
+        // skip don't-care patterns
+        if ( !Abc_InfoHasBit(pInfoCare, i) )
+        {
+            nDcs++;
+            continue;
+        }
+        // separate offset and onset patterns
+        if ( !Abc_InfoHasBit(pInfoNode, i) )
+            nZeros++;
+        else
+            nOnes++;
+    }
+    printf( "On = %3d (%7.2f %%)  ",  nOnes,  100.0*nOnes/p->nPats );
+    printf( "Off = %3d (%7.2f %%)  ", nZeros, 100.0*nZeros/p->nPats );
+    printf( "Dc = %3d (%7.2f %%)  ",  nDcs,   100.0*nDcs/p->nPats );
+    printf( "P0 = %3d ", p->nPats0 );
+    printf( "P1 = %3d ", p->nPats1 );
+    if ( p->nPats0 < 4 || p->nPats1 < 4 )
+        printf( "*" );
+    printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints output patterns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_SimPrintOutPatterns( Res_Sim_t * p, Abc_Ntk_t * pAig )
+{
+    Abc_Obj_t * pObj;
+    unsigned * pInfo2;
+    int i;
+    Abc_NtkForEachPo( pAig, pObj, i )
+    {
+        pInfo2 = Vec_PtrEntry( p->vOuts, i );
+        Extra_PrintBinary( stdout, pInfo2, p->nPatsOut );
+        printf( "\n" );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares simulation info for candidate filtering.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_SimPrepare( Res_Sim_t * p, Abc_Ntk_t * pAig, int nTruePis, int fVerbose )
+{
+    int Limit;
+    // prepare the manager
+    Res_SimAdjust( p, pAig );
+    // collect 0/1 simulation info
+    for ( Limit = 0; Limit < 10; Limit++ )
+    {
+        Res_SimSetRandom( p );
+        Res_SimPerformRound( p );
+        Res_SimProcessPats( p );
+        if ( !(p->nPats0 < p->nPats || p->nPats1 < p->nPats) )
+            break;
+    }
+//    printf( "%d   ", Limit );
+    // report the last set of patterns
+//    Res_SimReportOne( p );
+//    printf( "\n" );
+    // quit if there is not enough
+//    if ( p->nPats0 < 4 || p->nPats1 < 4 )
+    if ( p->nPats0 < 4 || p->nPats1 < 4 )
+    {
+//        Res_SimReportOne( p );
+        return 0;
+    }
+    // create bit-matrix info
+    if ( p->nPats0 < p->nPats )
+        Res_SimPadSimInfo( p->vPats0, p->nPats0, p->nWords );
+    if ( p->nPats1 < p->nPats )
+        Res_SimPadSimInfo( p->vPats1, p->nPats1, p->nWords );
+    // resimulate 0-patterns
+    Res_SimSetGiven( p, p->vPats0 );
+    Res_SimPerformRound( p );
+    Res_SimDeriveInfoReplicate( p );
+    // resimulate 1-patterns
+    Res_SimSetGiven( p, p->vPats1 );
+    Res_SimPerformRound( p );
+    Res_SimDeriveInfoComplement( p );
+    // print output patterns
+//    Res_SimPrintOutPatterns( p, pAig );
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/resStrash.c b/src/opt/res/resStrash.c
new file mode 100644
index 00000000..fde842a4
--- /dev/null
+++ b/src/opt/res/resStrash.c
@@ -0,0 +1,117 @@
+/**CFile****************************************************************
+
+  FileName    [resStrash.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Structural hashing of the nodes in the window.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resStrash.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+extern Abc_Obj_t * Abc_ConvertAigToAig( Abc_Ntk_t * pAig, Abc_Obj_t * pObjOld );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Structurally hashes the given window.]
+
+  Description [The first PO is the observability condition. The second 
+  is the node's function. The remaining POs are the candidate divisors.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Res_WndStrash( Res_Win_t * p )
+{
+    Vec_Ptr_t * vPairs;
+    Abc_Ntk_t * pAig;
+    Abc_Obj_t * pObj, * pMiter;
+    int i;
+    assert( Abc_NtkHasAig(p->pNode->pNtk) );
+//    Abc_NtkCleanCopy( p->pNode->pNtk );
+    // create the network
+    pAig = Abc_NtkAlloc( ABC_NTK_STRASH, ABC_FUNC_AIG, 1 );
+    pAig->pName = Extra_UtilStrsav( "window" );
+    // create the inputs
+    Vec_PtrForEachEntry( p->vLeaves, pObj, i )
+        pObj->pCopy = Abc_NtkCreatePi( pAig );
+    Vec_PtrForEachEntry( p->vBranches, pObj, i )
+        pObj->pCopy = Abc_NtkCreatePi( pAig );
+    // go through the nodes in the topological order
+    Vec_PtrForEachEntry( p->vNodes, pObj, i )
+    {
+        pObj->pCopy = Abc_ConvertAigToAig( pAig, pObj );
+        if ( pObj == p->pNode )
+            pObj->pCopy = Abc_ObjNot( pObj->pCopy );
+    }
+    // collect the POs
+    vPairs = Vec_PtrAlloc( 2 * Vec_PtrSize(p->vRoots) );
+    Vec_PtrForEachEntry( p->vRoots, pObj, i )
+    {
+        Vec_PtrPush( vPairs, pObj->pCopy );
+        Vec_PtrPush( vPairs, NULL );
+    }
+    // mark the TFO of the node
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Res_WinSweepLeafTfo_rec( p->pNode, (int)p->pNode->Level + p->nWinTfoMax );
+    // update strashing of the node
+    p->pNode->pCopy = Abc_ObjNot( p->pNode->pCopy );
+    Abc_NodeSetTravIdPrevious( p->pNode );
+    // redo strashing in the TFO
+    Vec_PtrForEachEntry( p->vNodes, pObj, i )
+    {
+        if ( Abc_NodeIsTravIdCurrent(pObj) )
+            pObj->pCopy = Abc_ConvertAigToAig( pAig, pObj );
+    }
+    // collect the POs
+    Vec_PtrForEachEntry( p->vRoots, pObj, i )
+        Vec_PtrWriteEntry( vPairs, 2 * i + 1, pObj->pCopy );
+    // add the miter
+    pMiter = Abc_AigMiter( pAig->pManFunc, vPairs );
+    Abc_ObjAddFanin( Abc_NtkCreatePo(pAig), pMiter );
+    Vec_PtrFree( vPairs );
+    // add the node
+    Abc_ObjAddFanin( Abc_NtkCreatePo(pAig), p->pNode->pCopy );
+    // add the fanins
+    Abc_ObjForEachFanin( p->pNode, pObj, i )
+        Abc_ObjAddFanin( Abc_NtkCreatePo(pAig), pObj->pCopy );
+    // add the divisors
+    Vec_PtrForEachEntry( p->vDivs, pObj, i )
+        Abc_ObjAddFanin( Abc_NtkCreatePo(pAig), pObj->pCopy );
+    // add the names
+    Abc_NtkAddDummyPiNames( pAig );
+    Abc_NtkAddDummyPoNames( pAig );
+    // check the resulting network
+    if ( !Abc_NtkCheck( pAig ) )
+        fprintf( stdout, "Res_WndStrash(): Network check has failed.\n" );
+    return pAig;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/resWin.c b/src/opt/res/resWin.c
new file mode 100644
index 00000000..a3648925
--- /dev/null
+++ b/src/opt/res/resWin.c
@@ -0,0 +1,485 @@
+/**CFile****************************************************************
+
+  FileName    [resWin.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    [Windowing algorithm.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: resWin.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "resInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates the window.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Res_Win_t * Res_WinAlloc()
+{
+    Res_Win_t * p;
+    // start the manager
+    p = ALLOC( Res_Win_t, 1 );
+    memset( p, 0, sizeof(Res_Win_t) );
+    // set internal parameters
+    p->nFanoutLimit = 10;
+    p->nLevTfiMinus =  3;
+    // allocate storage
+    p->vRoots    = Vec_PtrAlloc( 256 );
+    p->vLeaves   = Vec_PtrAlloc( 256 );
+    p->vBranches = Vec_PtrAlloc( 256 );
+    p->vNodes    = Vec_PtrAlloc( 256 );
+    p->vDivs     = Vec_PtrAlloc( 256 );
+    p->vMatrix   = Vec_VecStart( 128 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Frees the window.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinFree( Res_Win_t * p )
+{
+    Vec_PtrFree( p->vRoots  );
+    Vec_PtrFree( p->vLeaves );
+    Vec_PtrFree( p->vBranches );
+    Vec_PtrFree( p->vNodes  );
+    Vec_PtrFree( p->vDivs   );
+    Vec_VecFree( p->vMatrix );
+    free( p );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Collect the limited TFI cone of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_WinCollectLeavesAndNodes( Res_Win_t * p )
+{
+    Vec_Ptr_t * vFront;
+    Abc_Obj_t * pObj, * pTemp;
+    int i, k, m;
+
+    assert( p->nWinTfiMax > 0 );
+    assert( Vec_VecSize(p->vMatrix) > p->nWinTfiMax );
+
+    // start matrix with the node
+    Vec_VecClear( p->vMatrix );
+    Vec_VecPush( p->vMatrix, 0, p->pNode );
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Abc_NodeSetTravIdCurrent( p->pNode );
+
+    // collect the leaves (nodes pTemp such that "p->pNode->Level - pTemp->Level > p->nWinTfiMax")
+    Vec_PtrClear( p->vLeaves );
+    Vec_VecForEachLevelStartStop( p->vMatrix, vFront, i, 0, p->nWinTfiMax )
+    {
+        Vec_PtrForEachEntry( vFront, pObj, k )
+        {
+            Abc_ObjForEachFanin( pObj, pTemp, m )
+            {
+                if ( Abc_NodeIsTravIdCurrent( pTemp ) )
+                    continue;
+                Abc_NodeSetTravIdCurrent( pTemp );
+                if ( Abc_ObjIsCi(pTemp) || (int)(p->pNode->Level - pTemp->Level) > p->nWinTfiMax )                    
+                    Vec_PtrPush( p->vLeaves, pTemp );
+                else
+                    Vec_VecPush( p->vMatrix, p->pNode->Level - pTemp->Level, pTemp );
+            }
+        }
+    }
+    if ( Vec_PtrSize(p->vLeaves) == 0 )
+        return 0;
+
+    // collect the nodes in the reverse order
+    Vec_PtrClear( p->vNodes );
+    Vec_VecForEachLevelReverseStartStop( p->vMatrix, vFront, i, p->nWinTfiMax, 0 )
+    {
+        Vec_PtrForEachEntry( vFront, pObj, k )
+            Vec_PtrPush( p->vNodes, pObj );
+        Vec_PtrClear( vFront );
+    }
+
+    // get the lowest leaf level
+    p->nLevLeafMin = ABC_INFINITY;
+    Vec_PtrForEachEntry( p->vLeaves, pObj, k )
+        p->nLevLeafMin = ABC_MIN( p->nLevLeafMin, (int)pObj->Level );
+
+    // set minimum traversal level
+    p->nLevTravMin = ABC_MAX( ((int)p->pNode->Level) - p->nWinTfiMax - p->nLevTfiMinus, p->nLevLeafMin );
+    assert( p->nLevTravMin >= 0 );
+    return 1;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the node should be a root.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Res_WinComputeRootsCheck( Abc_Obj_t * pNode, int nLevelMax, int nFanoutLimit )
+{
+    Abc_Obj_t * pFanout;
+    int i;
+    // the node is the root if one of the following is true:
+    // (1) the node has more than fanouts than the limit
+    if ( Abc_ObjFanoutNum(pNode) > nFanoutLimit )
+        return 1;
+    // (2) the node has CO fanouts
+    // (3) the node has fanouts above the cutoff level
+    Abc_ObjForEachFanout( pNode, pFanout, i )
+        if ( Abc_ObjIsCo(pFanout) || (int)pFanout->Level > nLevelMax )
+            return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively collects the root candidates.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinComputeRoots_rec( Abc_Obj_t * pNode, int nLevelMax, int nFanoutLimit, Vec_Ptr_t * vRoots )
+{
+    Abc_Obj_t * pFanout;
+    int i;
+    assert( Abc_ObjIsNode(pNode) );
+    if ( Abc_NodeIsTravIdCurrent(pNode) )
+        return;
+    Abc_NodeSetTravIdCurrent( pNode );
+    // check if the node should be the root
+    if ( Res_WinComputeRootsCheck( pNode, nLevelMax, nFanoutLimit ) )
+        Vec_PtrPush( vRoots, pNode );
+    else // if not, explore its fanouts
+        Abc_ObjForEachFanout( pNode, pFanout, i )
+            Res_WinComputeRoots_rec( pFanout, nLevelMax, nFanoutLimit, vRoots );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively collects the root candidates.]
+
+  Description [Returns 1 if the only root is this node.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_WinComputeRoots( Res_Win_t * p )
+{
+    Vec_PtrClear( p->vRoots );
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Res_WinComputeRoots_rec( p->pNode, p->pNode->Level + p->nWinTfoMax, p->nFanoutLimit, p->vRoots );
+    assert( Vec_PtrSize(p->vRoots) > 0 );
+    if ( Vec_PtrSize(p->vRoots) == 1 && Vec_PtrEntry(p->vRoots, 0) == p->pNode )
+        return 0;
+    return 1;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the paths from the roots to the leaves.]
+
+  Description [Returns 1 if the the node can reach a leaf.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_WinMarkPaths_rec( Abc_Obj_t * pNode, Abc_Obj_t * pPivot, int nLevelMin )
+{
+    Abc_Obj_t * pFanin;
+    int i, RetValue;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pNode) )
+        return 1;
+    if ( Abc_NodeIsTravIdPrevious(pNode) )
+        return 0;
+    // assume that the node does not have access to the leaves
+    Abc_NodeSetTravIdPrevious( pNode );
+    // skip nodes below the given level
+    if ( pNode == pPivot || (int)pNode->Level <= nLevelMin )
+        return 0;
+    assert( Abc_ObjIsNode(pNode) );
+    // check if the fanins have access to the leaves
+    RetValue = 0;
+    Abc_ObjForEachFanin( pNode, pFanin, i )
+        RetValue |= Res_WinMarkPaths_rec( pFanin, pPivot, nLevelMin );
+    // relabel the node if it has access to the leaves
+    if ( RetValue )
+        Abc_NodeSetTravIdCurrent( pNode );
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the paths from the roots to the leaves.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinMarkPaths( Res_Win_t * p )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    // mark the leaves
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Vec_PtrForEachEntry( p->vLeaves, pObj, i )
+        Abc_NodeSetTravIdCurrent( pObj );
+    // traverse from the roots and mark the nodes that can reach leaves
+    // the nodes that do not reach leaves have previous trav ID
+    // the nodes that reach leaves have current trav ID
+    Vec_PtrForEachEntry( p->vRoots, pObj, i )
+        Res_WinMarkPaths_rec( pObj, p->pNode, p->nLevTravMin );
+}
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively collects the roots.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinFinalizeRoots_rec( Abc_Obj_t * pObj, Vec_Ptr_t * vRoots )
+{
+    Abc_Obj_t * pFanout;
+    int i;
+    assert( Abc_ObjIsNode(pObj) );
+    assert( Abc_NodeIsTravIdCurrent(pObj) );
+    // check if the node has all fanouts marked
+    Abc_ObjForEachFanout( pObj, pFanout, i )
+        if ( !Abc_NodeIsTravIdCurrent(pFanout) )
+            break;
+    // if some of the fanouts are unmarked, add the node to the roots
+    if ( i < Abc_ObjFanoutNum(pObj) ) 
+        Vec_PtrPushUnique( vRoots, pObj );
+    else  // otherwise, call recursively
+        Abc_ObjForEachFanout( pObj, pFanout, i )
+            Res_WinFinalizeRoots_rec( pFanout, vRoots );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finalizes the roots of the window.]
+
+  Description [Roots of the window are the nodes that have at least
+  one fanout that it not in the TFO of the leaves.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_WinFinalizeRoots( Res_Win_t * p )
+{
+    assert( !Abc_NodeIsTravIdCurrent(p->pNode) );
+    // mark the node with the old traversal ID
+    Abc_NodeSetTravIdCurrent( p->pNode ); 
+    // recollect the roots
+    Vec_PtrClear( p->vRoots );
+    Res_WinFinalizeRoots_rec( p->pNode, p->vRoots );
+    assert( Vec_PtrSize(p->vRoots) > 0 );
+    if ( Vec_PtrSize(p->vRoots) == 1 && Vec_PtrEntry(p->vRoots, 0) == p->pNode )
+        return 0;
+    return 1;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively adds missing nodes and leaves.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinAddMissing_rec( Res_Win_t * p, Abc_Obj_t * pObj, int nLevTravMin )
+{
+    Abc_Obj_t * pFanin;
+    int i;
+    // skip the already collected leaves, nodes, and branches
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return;
+    // if this is not an internal node - make it a new branch
+    if ( !Abc_NodeIsTravIdPrevious(pObj) )
+    {
+        assert( Vec_PtrFind(p->vLeaves, pObj) == -1 );
+        Abc_NodeSetTravIdCurrent( pObj );
+        Vec_PtrPush( p->vBranches, pObj );
+        return;
+    }
+    assert( Abc_ObjIsNode(pObj) ); // if this is a CI, then the window is incorrect!
+    Abc_NodeSetTravIdCurrent( pObj );
+    // visit the fanins of the node
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+        Res_WinAddMissing_rec( p, pFanin, nLevTravMin );
+    // collect the node
+    Vec_PtrPush( p->vNodes, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds to the window nodes and leaves in the TFI of the roots.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Res_WinAddMissing( Res_Win_t * p )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    // mark the leaves
+    Abc_NtkIncrementTravId( p->pNode->pNtk );
+    Vec_PtrForEachEntry( p->vLeaves, pObj, i )
+        Abc_NodeSetTravIdCurrent( pObj );        
+    // mark the already collected nodes
+    Vec_PtrForEachEntry( p->vNodes, pObj, i )
+        Abc_NodeSetTravIdCurrent( pObj );        
+    // explore from the roots
+    Vec_PtrClear( p->vBranches );
+    Vec_PtrForEachEntry( p->vRoots, pObj, i )
+        Res_WinAddMissing_rec( p, pObj, p->nLevTravMin );
+}
+
+
+
+ 
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the window is trivial (without TFO).]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_WinIsTrivial( Res_Win_t * p )
+{
+    return Vec_PtrSize(p->vRoots) == 1 && Vec_PtrEntry(p->vRoots, 0) == p->pNode;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the window.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Res_WinCompute( Abc_Obj_t * pNode, int nWinTfiMax, int nWinTfoMax, Res_Win_t * p )
+{
+    assert( Abc_ObjIsNode(pNode) );
+    assert( nWinTfiMax > 0 && nWinTfiMax < 10 );
+    assert( nWinTfoMax >= 0 && nWinTfoMax < 10 );
+
+    // initialize the window
+    p->pNode      = pNode;
+    p->nWinTfiMax = nWinTfiMax;
+    p->nWinTfoMax = nWinTfoMax;
+
+    Vec_PtrClear( p->vBranches );
+    Vec_PtrClear( p->vDivs );
+    Vec_PtrClear( p->vRoots );
+    Vec_PtrPush( p->vRoots, pNode );
+
+    // compute the leaves
+    if ( !Res_WinCollectLeavesAndNodes( p ) )
+        return 0;
+
+    // compute the candidate roots
+    if ( p->nWinTfoMax > 0 && Res_WinComputeRoots(p) )
+    {
+        // mark the paths from the roots to the leaves
+        Res_WinMarkPaths( p );
+        // refine the roots and add branches and missing nodes
+        if ( Res_WinFinalizeRoots( p ) )
+            Res_WinAddMissing( p );
+    }
+
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/res/res_.c b/src/opt/res/res_.c
new file mode 100644
index 00000000..a50affd7
--- /dev/null
+++ b/src/opt/res/res_.c
@@ -0,0 +1,50 @@
+/**CFile****************************************************************
+
+  FileName    [res_.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Resynthesis package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - January 15, 2007.]
+
+  Revision    [$Id: res_.c,v 1.00 2007/01/15 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "res.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/module.make b/src/opt/ret/module.make
new file mode 100644
index 00000000..4b14365e
--- /dev/null
+++ b/src/opt/ret/module.make
@@ -0,0 +1,8 @@
+SRC +=  src/opt/ret/retArea.c \
+        src/opt/ret/retCore.c \
+        src/opt/ret/retDelay.c \
+        src/opt/ret/retFlow.c \
+        src/opt/ret/retIncrem.c \
+        src/opt/ret/retInit.c \
+        src/opt/ret/retLvalue.c
+
diff --git a/src/opt/ret/retArea.c b/src/opt/ret/retArea.c
new file mode 100644
index 00000000..5eec8e80
--- /dev/null
+++ b/src/opt/ret/retArea.c
@@ -0,0 +1,540 @@
+/**CFile****************************************************************
+
+  FileName    [retArea.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    [Min-area retiming.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retArea.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Abc_Ntk_t * Abc_NtkRetimeMinAreaOne( Abc_Ntk_t * pNtk, int fForward, int fVerbose );
+static void        Abc_NtkRetimeMinAreaPrepare( Abc_Ntk_t * pNtk, int fForward );
+static void        Abc_NtkRetimeMinAreaInitValues( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut );
+static Abc_Ntk_t * Abc_NtkRetimeMinAreaConstructNtk( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut );
+static void        Abc_NtkRetimeMinAreaUpdateLatches( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut, int fForward );
+
+extern Abc_Ntk_t * Abc_NtkAttachBottom( Abc_Ntk_t * pNtkTop, Abc_Ntk_t * pNtkBottom );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs min-area retiming.]
+
+  Description [Returns the number of latches reduced.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeMinArea( Abc_Ntk_t * pNtk, int fForwardOnly, int fBackwardOnly, int fVerbose )
+{
+    Abc_Ntk_t * pNtkTotal = NULL, * pNtkBottom;
+    Vec_Int_t * vValuesNew = NULL, * vValues;
+    int nLatches = Abc_NtkLatchNum(pNtk);
+    int fOneFrame = 0;
+    assert( !fForwardOnly || !fBackwardOnly );
+    // there should not be black boxes
+    assert( Abc_NtkIsSopLogic(pNtk) );
+    assert( Abc_NtkLatchNum(pNtk) == Vec_PtrSize(pNtk->vBoxes) );
+    // reorder CI/CO/latch inputs
+    Abc_NtkOrderCisCos( pNtk );
+    // perform forward retiming
+    if ( !fBackwardOnly )
+    {
+        if ( fOneFrame )
+            Abc_NtkRetimeMinAreaOne( pNtk, 1, fVerbose );
+        else
+            while ( Abc_NtkRetimeMinAreaOne( pNtk, 1, fVerbose ) );
+    }
+    // remember initial values
+    vValues = Abc_NtkCollectLatchValues( pNtk );
+    // perform backward retiming
+    if ( !fForwardOnly )
+    {
+        if ( fOneFrame )
+            pNtkTotal = Abc_NtkRetimeMinAreaOne( pNtk, 0, fVerbose );
+        else
+            while ( pNtkBottom = Abc_NtkRetimeMinAreaOne( pNtk, 0, fVerbose ) )
+                pNtkTotal = Abc_NtkAttachBottom( pNtkTotal, pNtkBottom );  
+    }
+    // compute initial values
+    vValuesNew = Abc_NtkRetimeInitialValues( pNtkTotal, vValues, fVerbose );
+    if ( pNtkTotal ) Abc_NtkDelete( pNtkTotal );
+    // insert new initial values
+    Abc_NtkInsertLatchValues( pNtk, vValuesNew );
+    if ( vValuesNew ) Vec_IntFree( vValuesNew );
+    if ( vValues )    Vec_IntFree( vValues );
+    // fix the COs (this changes the circuit structure)
+//    Abc_NtkLogicMakeSimpleCos( pNtk, 0 );
+    // check for correctness
+    if ( !Abc_NtkCheck( pNtk ) )
+        fprintf( stdout, "Abc_NtkRetimeMinArea(): Network check has failed.\n" );
+    // return the number of latches saved
+    return nLatches - Abc_NtkLatchNum(pNtk);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs min-area retiming backward.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Abc_NtkRetimeMinAreaOne( Abc_Ntk_t * pNtk, int fForward, int fVerbose )
+{ 
+    Abc_Ntk_t * pNtkNew = NULL;
+    Vec_Ptr_t * vMinCut;
+    int nLatches = Abc_NtkLatchNum(pNtk);
+    // mark current latches and TFI(POs)
+    Abc_NtkRetimeMinAreaPrepare( pNtk, fForward );
+    // run the maximum forward flow
+    vMinCut = Abc_NtkMaxFlow( pNtk, fForward, fVerbose );
+//    assert( Vec_PtrSize(vMinCut) <= Abc_NtkLatchNum(pNtk) );
+    // create new latch boundary if there is improvement
+    if ( Vec_PtrSize(vMinCut) < Abc_NtkLatchNum(pNtk) )
+    {
+        pNtkNew = (Abc_Ntk_t *)1;
+        if ( fForward )
+            Abc_NtkRetimeMinAreaInitValues( pNtk, vMinCut );
+        else
+            pNtkNew = Abc_NtkRetimeMinAreaConstructNtk( pNtk, vMinCut );
+        Abc_NtkRetimeMinAreaUpdateLatches( pNtk, vMinCut, fForward );
+    }
+    // clean up
+    Vec_PtrFree( vMinCut );
+    Abc_NtkCleanMarkA( pNtk );
+    return pNtkNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the cone with MarkA.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkMarkCone_rec( Abc_Obj_t * pObj, int fForward )
+{
+    Abc_Obj_t * pNext;
+    int i;
+    if ( pObj->fMarkA )
+        return;
+    pObj->fMarkA = 1;
+    if ( fForward )
+    {
+        Abc_ObjForEachFanout( pObj, pNext, i )
+            Abc_NtkMarkCone_rec( pNext, fForward );
+    }
+    else
+    {
+        Abc_ObjForEachFanin( pObj, pNext, i )
+            Abc_NtkMarkCone_rec( pNext, fForward );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the cone with MarkA.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkUnmarkCone_rec( Abc_Obj_t * pObj, int fForward )
+{
+    Abc_Obj_t * pNext;
+    int i;
+    if ( !pObj->fMarkA || Abc_ObjIsLatch(pObj) )
+        return;
+    pObj->fMarkA = 0;
+    if ( fForward )
+    {
+        Abc_ObjForEachFanout( pObj, pNext, i )
+            Abc_NtkUnmarkCone_rec( pNext, fForward );
+    }
+    else
+    {
+        Abc_ObjForEachFanin( pObj, pNext, i )
+            Abc_NtkUnmarkCone_rec( pNext, fForward );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares the network for running MaxFlow.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeMinAreaPrepare( Abc_Ntk_t * pNtk, int fForward )
+{
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pObj, * pFanin;
+    int i, k;
+    if ( fForward )
+    {
+        // mark the frontier
+        Abc_NtkForEachPo( pNtk, pObj, i )
+            pObj->fMarkA = 1;
+        Abc_NtkForEachLatch( pNtk, pObj, i )
+        {
+            pObj->fMarkA = 1;
+            Abc_ObjFanin0(pObj)->fMarkA = 1;
+        }
+        // mark the nodes reachable from the PIs
+        Abc_NtkForEachPi( pNtk, pObj, i )
+            Abc_NtkMarkCone_rec( pObj, fForward );
+        // collect the unmarked fanins of the marked nodes
+        vNodes = Vec_PtrAlloc( 100 );
+        Abc_NtkForEachObj( pNtk, pObj, i )
+            if ( pObj->fMarkA )
+                Abc_ObjForEachFanin( pObj, pFanin, k )
+                    if ( !pFanin->fMarkA )
+                        Vec_PtrPush( vNodes, pFanin );
+        // mark these nodes
+        Vec_PtrForEachEntry( vNodes, pObj, i )
+            pObj->fMarkA = 1;
+        Vec_PtrFree( vNodes );
+    }
+    else
+    {
+        // mark the frontier
+        Abc_NtkForEachPi( pNtk, pObj, i )
+            pObj->fMarkA = 1;
+        Abc_NtkForEachLatch( pNtk, pObj, i )
+        {
+            pObj->fMarkA = 1;
+            Abc_ObjFanout0(pObj)->fMarkA = 1;
+        }
+        // mark the nodes reachable from the POs
+        Abc_NtkForEachPo( pNtk, pObj, i )
+            Abc_NtkMarkCone_rec( pObj, fForward );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compute initial values.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeMinAreaInitValues_rec( Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pFanin;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return (int)pObj->pCopy;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // consider the case of a latch output
+    if ( Abc_ObjIsBo(pObj) )
+    {
+        assert( Abc_ObjIsLatch(Abc_ObjFanin0(pObj)) );
+        pObj->pCopy = (void *)Abc_NtkRetimeMinAreaInitValues_rec( Abc_ObjFanin0(pObj) );
+        return (int)pObj->pCopy;
+    }
+    assert( Abc_ObjIsNode(pObj) );
+    // visit the fanins
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+        Abc_NtkRetimeMinAreaInitValues_rec( pFanin );
+    // compute the value of the node
+    pObj->pCopy = (void *)Abc_ObjSopSimulate(pObj);
+    return (int)pObj->pCopy;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compute initial values.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeMinAreaInitValues( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    // transfer initial values to pCopy and mark the latches
+    Abc_NtkIncrementTravId(pNtk);
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+    {
+        pObj->pCopy = (void *)Abc_LatchIsInit1(pObj);
+        Abc_NodeSetTravIdCurrent( pObj );
+    }
+    // propagate initial values
+    Vec_PtrForEachEntry( vMinCut, pObj, i )
+        Abc_NtkRetimeMinAreaInitValues_rec( pObj );
+    // unmark the latches
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        Abc_NodeSetTravIdPrevious( pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs min-area retiming backward.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkRetimeMinAreaConstructNtk_rec( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pFanin;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return pObj->pCopy;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // consider the case of a latch output
+    if ( Abc_ObjIsBi(pObj) )
+    {
+        pObj->pCopy = Abc_NtkRetimeMinAreaConstructNtk_rec( pNtkNew, Abc_ObjFanin0(pObj) );
+        return pObj->pCopy;
+    }
+    assert( Abc_ObjIsNode(pObj) );
+    // visit the fanins
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+        Abc_NtkRetimeMinAreaConstructNtk_rec( pNtkNew, pFanin );
+    // compute the value of the node
+    Abc_NtkDupObj( pNtkNew, pObj, 0 );
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+        Abc_ObjAddFanin( pObj->pCopy, pFanin->pCopy );
+    return pObj->pCopy;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the network from computing initial state.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Abc_NtkRetimeMinAreaConstructNtk( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut )
+{
+    Abc_Ntk_t * pNtkNew;
+    Abc_Obj_t * pObj, * pObjNew;
+    int i;
+    // create new network
+    pNtkNew = Abc_NtkAlloc( ABC_NTK_LOGIC, ABC_FUNC_SOP, 1 );
+    // map new latches into PIs of the new network
+    Abc_NtkIncrementTravId(pNtk);
+    Vec_PtrForEachEntry( vMinCut, pObj, i )
+    {
+        pObj->pCopy = Abc_NtkCreatePi(pNtkNew);
+        Abc_NodeSetTravIdCurrent( pObj );
+    }
+    // construct the network recursively
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+    {
+        pObjNew = Abc_NtkRetimeMinAreaConstructNtk_rec( pNtkNew, Abc_ObjFanin0(pObj) );
+        Abc_ObjAddFanin( Abc_NtkCreatePo(pNtkNew), pObjNew );
+    }
+    // unmark the nodes in the cut
+    Vec_PtrForEachEntry( vMinCut, pObj, i )
+        Abc_NodeSetTravIdPrevious( pObj );
+    // unmark the latches
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        Abc_NodeSetTravIdPrevious( pObj );
+    // assign dummy node names
+    Abc_NtkAddDummyPiNames( pNtkNew );
+    Abc_NtkAddDummyPoNames( pNtkNew );
+    if ( !Abc_NtkCheck( pNtkNew ) )
+        fprintf( stdout, "Abc_NtkRetimeMinAreaConstructNtk(): Network check has failed.\n" );
+    return pNtkNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the network after backward retiming.]
+
+  Description [Assumes that fMarkA denotes all nodes reachabe from
+  the latches toward the cut.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeMinAreaUpdateLatches( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut, int fForward )
+{
+    Vec_Ptr_t * vCis, * vCos, * vBoxes, * vBoxesNew, * vNodes, * vBuffers;
+    Abc_Obj_t * pObj, * pLatch, * pLatchIn, * pLatchOut, * pNext, * pBuffer;
+    int i, k;
+    // create new latches
+    Vec_PtrShrink( pNtk->vCis, Abc_NtkCiNum(pNtk) - Abc_NtkLatchNum(pNtk) );
+    Vec_PtrShrink( pNtk->vCos, Abc_NtkCoNum(pNtk) - Abc_NtkLatchNum(pNtk) );
+    vCis   = pNtk->vCis;   pNtk->vCis   = NULL;  
+    vCos   = pNtk->vCos;   pNtk->vCos   = NULL;  
+    vBoxes = pNtk->vBoxes; pNtk->vBoxes = NULL; 
+    // transfer boxes
+    vBoxesNew = Vec_PtrAlloc(100);
+    Vec_PtrForEachEntry( vBoxes, pObj, i )
+        if ( !Abc_ObjIsLatch(pObj) )
+            Vec_PtrPush( vBoxesNew, pObj );
+    // create or reuse latches
+    vNodes = Vec_PtrAlloc( 100 );
+    vBuffers = Vec_PtrAlloc( 100 );
+    Vec_PtrForEachEntry( vMinCut, pObj, i )
+    {
+        if ( Abc_ObjIsCi(pObj) && fForward )
+        {
+            pLatchOut = pObj;
+            pLatch    = Abc_ObjFanin0(pLatchOut);
+            pLatchIn  = Abc_ObjFanin0(pLatch);
+            assert( Abc_ObjIsBo(pLatchOut) && Abc_ObjIsLatch(pLatch) && Abc_ObjIsBi(pLatchIn) );
+            // mark the latch as reused
+            Abc_NodeSetTravIdCurrent( pLatch );
+
+            // check if there are marked fanouts
+            // (these are fanouts to be connected to the latch input)
+            Abc_ObjForEachFanout( pObj, pNext, k )
+                if ( pNext->fMarkA )
+                    break;
+            if ( k < Abc_ObjFanoutNum(pObj) )
+            {
+                // add the buffer
+                pBuffer = Abc_NtkCreateNodeBuf( pNtk, Abc_ObjFanin0(pLatchIn) );
+                Abc_ObjPatchFanin( pLatchIn, Abc_ObjFanin0(pLatchIn), pBuffer );
+                Vec_PtrPush( vBuffers, pBuffer );
+                // redirect edges to the unvisited fanouts of the node
+                Abc_NodeCollectFanouts( pObj, vNodes );
+                Vec_PtrForEachEntry( vNodes, pNext, k )
+                    if ( pNext->fMarkA )
+                        Abc_ObjPatchFanin( pNext, pObj, pBuffer );
+            }
+            assert( Abc_ObjFanoutNum(pObj) > 0 );
+//            if ( Abc_ObjFanoutNum(pObj) == 0 )
+//                Abc_NtkDeleteObj_rec( pObj, 0 );
+        }
+        else if ( Abc_ObjIsCo(pObj) && !fForward )
+        {
+            pLatchIn  = pObj;
+            pLatch    = Abc_ObjFanout0(pLatchIn);
+            pLatchOut = Abc_ObjFanout0(pLatch);
+            assert( Abc_ObjIsBo(pLatchOut) && Abc_ObjIsLatch(pLatch) && Abc_ObjIsBi(pLatchIn) );
+            // mark the latch as reused
+            Abc_NodeSetTravIdCurrent( pLatch );
+            assert( !Abc_ObjFanin0(pLatchIn)->fMarkA );
+        }
+        else
+        {
+            pLatchOut = Abc_NtkCreateBo(pNtk);
+            pLatch    = Abc_NtkCreateLatch(pNtk);
+            pLatchIn  = Abc_NtkCreateBi(pNtk);
+            Abc_ObjAssignName( pLatchOut, Abc_ObjName(pLatch), "_out" );
+            Abc_ObjAssignName( pLatchIn,  Abc_ObjName(pLatch), "_in" );
+            // connect
+            Abc_ObjAddFanin( pLatchOut, pLatch );
+            Abc_ObjAddFanin( pLatch, pLatchIn );
+            if ( fForward )
+            {
+                pLatch->pData = (void *)(pObj->pCopy? ABC_INIT_ONE : ABC_INIT_ZERO);
+                // redirect edges to the unvisited fanouts of the node
+                Abc_NodeCollectFanouts( pObj, vNodes );
+                Vec_PtrForEachEntry( vNodes, pNext, k )
+                    if ( !pNext->fMarkA )
+                        Abc_ObjPatchFanin( pNext, pObj, pLatchOut );
+            }
+            else
+            {
+                // redirect edges to the visited fanouts of the node
+                Abc_NodeCollectFanouts( pObj, vNodes );
+                Vec_PtrForEachEntry( vNodes, pNext, k )
+                    if ( pNext->fMarkA )
+                        Abc_ObjPatchFanin( pNext, pObj, pLatchOut );
+            }
+            // connect latch to the node
+            Abc_ObjAddFanin( pLatchIn, pObj );
+        }
+        Vec_PtrPush( vCis, pLatchOut );
+        Vec_PtrPush( vBoxesNew, pLatch );
+        Vec_PtrPush( vCos, pLatchIn );
+    }
+    Vec_PtrFree( vNodes );
+    // remove buffers
+    Vec_PtrForEachEntry( vBuffers, pObj, i )
+    {
+        Abc_ObjTransferFanout( pObj, Abc_ObjFanin0(pObj) );
+        Abc_NtkDeleteObj( pObj );
+    }
+    Vec_PtrFree( vBuffers );
+    // remove useless latches
+    Vec_PtrForEachEntry( vBoxes, pObj, i )
+    {
+        if ( !Abc_ObjIsLatch(pObj) )
+            continue;
+        if ( Abc_NodeIsTravIdCurrent(pObj) )
+            continue;
+        pLatchOut = Abc_ObjFanout0(pObj);
+        pLatch    = pObj;
+        pLatchIn  = Abc_ObjFanin0(pObj);
+        if ( Abc_ObjFanoutNum(pLatchOut) > 0 )
+            Abc_ObjTransferFanout( pLatchOut, Abc_ObjFanin0(pLatchIn) );
+        Abc_NtkDeleteObj( pLatchOut );
+        Abc_NtkDeleteObj( pObj );
+        Abc_NtkDeleteObj( pLatchIn );
+    }
+    // set the arrays
+    pNtk->vCis = vCis;
+    pNtk->vCos = vCos;
+    pNtk->vBoxes = vBoxesNew;
+    Vec_PtrFree( vBoxes );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/retCore.c b/src/opt/ret/retCore.c
new file mode 100644
index 00000000..47b2cbbc
--- /dev/null
+++ b/src/opt/ret/retCore.c
@@ -0,0 +1,132 @@
+/**CFile****************************************************************
+
+  FileName    [retCore.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    [The core retiming procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retCore.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+int timeRetime = 0;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Implementation of retiming.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetime( Abc_Ntk_t * pNtk, int Mode, int fForwardOnly, int fBackwardOnly, int fOneStep, int fVerbose )
+{
+    int nLatches = Abc_NtkLatchNum(pNtk);
+    int nLevels  = Abc_NtkLevel(pNtk);
+    int RetValue = 0, clkTotal = clock();
+    int nNodesOld, nLatchesOld;
+    assert( Mode > 0 && Mode < 7 );
+    assert( !fForwardOnly || !fBackwardOnly );
+
+    // cleanup the network
+    nNodesOld   = Abc_NtkNodeNum(pNtk);
+    nLatchesOld = Abc_NtkLatchNum(pNtk);
+    Abc_NtkCleanupSeq(pNtk, 0, 0, 0);
+    if ( nNodesOld > Abc_NtkNodeNum(pNtk) || nLatchesOld > Abc_NtkLatchNum(pNtk) )
+        printf( "Cleanup before retiming removed %d dangling nodes and %d dangling latches.\n",
+            nNodesOld - Abc_NtkNodeNum(pNtk), nLatchesOld - Abc_NtkLatchNum(pNtk) );
+
+    // perform retiming
+    switch ( Mode )
+    {
+    case 1: // forward 
+        RetValue = Abc_NtkRetimeIncremental( pNtk, 1, 0, 0, fVerbose );
+        break;
+    case 2: // backward 
+        RetValue = Abc_NtkRetimeIncremental( pNtk, 0, 0, 0, fVerbose );
+        break;
+    case 3: // min-area 
+        RetValue = Abc_NtkRetimeMinArea( pNtk, fForwardOnly, fBackwardOnly, fVerbose );
+        break;
+    case 4: // min-delay
+        if ( !fBackwardOnly )
+            RetValue += Abc_NtkRetimeIncremental( pNtk, 1, 1, fOneStep, fVerbose );
+        if ( !fForwardOnly )
+            RetValue += Abc_NtkRetimeIncremental( pNtk, 0, 1, fOneStep, fVerbose );
+        break;
+    case 5: // min-area + min-delay
+        RetValue  = Abc_NtkRetimeMinArea( pNtk, fForwardOnly, fBackwardOnly, fVerbose );
+        if ( !fBackwardOnly )
+            RetValue += Abc_NtkRetimeIncremental( pNtk, 1, 1, 0, fVerbose );
+        if ( !fForwardOnly )
+            RetValue += Abc_NtkRetimeIncremental( pNtk, 0, 1, 0, fVerbose );
+        break;
+    case 6: // Pan's algorithm
+        RetValue = Abc_NtkRetimeLValue( pNtk, 500, fVerbose );
+        break;
+    default:
+        printf( "Unknown retiming option.\n" );
+        break;
+    }
+    if ( fVerbose )
+    {
+        printf( "Reduction in area = %3d. Reduction in delay = %3d. ", 
+            nLatches - Abc_NtkLatchNum(pNtk), nLevels - Abc_NtkLevel(pNtk) );
+        PRT( "Total runtime", clock() - clkTotal );
+    }
+    timeRetime = clock() - clkTotal;
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Used for automated debugging.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeDebug( Abc_Ntk_t * pNtk )
+{
+    extern int Abc_NtkSecFraig( Abc_Ntk_t * pNtk1, Abc_Ntk_t * pNtk2, int nSeconds, int nFrames, int fVerbose );
+    Abc_Ntk_t * pNtkRet;
+    assert( Abc_NtkIsLogic(pNtk) );
+    Abc_NtkToSop( pNtk, 0 );
+//    if ( !Abc_NtkCheck( pNtk ) )
+//        fprintf( stdout, "Abc_NtkRetimeDebug(): Network check has failed.\n" );
+//    Io_WriteBlifLogic( pNtk, "debug_temp.blif", 1 );
+    pNtkRet = Abc_NtkDup( pNtk );
+    Abc_NtkRetime( pNtkRet, 3, 0, 1, 0, 0 ); // debugging backward flow
+    return !Abc_NtkSecFraig( pNtk, pNtkRet, 10000, 3, 0 );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/retDelay.c b/src/opt/ret/retDelay.c
new file mode 100644
index 00000000..bcfe3a2e
--- /dev/null
+++ b/src/opt/ret/retDelay.c
@@ -0,0 +1,305 @@
+/**CFile****************************************************************
+
+  FileName    [retDelay.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    [Incremental retiming for optimum delay.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retDelay.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Abc_NtkRetimeMinDelayTry( Abc_Ntk_t * pNtk, int fForward, int fInitial, int nIterLimit, int * pIterBest, int fVerbose );
+static int Abc_NtkRetimeTiming( Abc_Ntk_t * pNtk, int fForward, Vec_Ptr_t * vCritical );
+static int Abc_NtkRetimeTiming_rec( Abc_Obj_t * pObj, int fForward );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Retimes incrementally for minimum delay.]
+
+  Description [This procedure cannot be called in the application code
+  because it assumes that the network is preprocessed by removing LIs/LOs.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeMinDelay( Abc_Ntk_t * pNtk, Abc_Ntk_t * pNtkCopy, int nIterLimit, int fForward, int fVerbose )
+{
+    int IterBest, DelayBest;
+    int IterBest2, DelayBest2;
+    // try to find the best delay iteration on a copy
+    DelayBest = Abc_NtkRetimeMinDelayTry( pNtkCopy, fForward, 0, nIterLimit, &IterBest, fVerbose );
+    if ( IterBest == 0 )
+        return 1;
+    // perform the given number of iterations on the original network
+    DelayBest2 = Abc_NtkRetimeMinDelayTry( pNtk, fForward, 1, IterBest, &IterBest2, fVerbose );
+    assert( DelayBest == DelayBest2 );
+    assert( IterBest == IterBest2 );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the best delay and the number of best iteration.]
+
+  Description [] 
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeMinDelayTry( Abc_Ntk_t * pNtk, int fForward, int fInitial, int nIterLimit, int * pIterBest, int fVerbose )
+{
+    Abc_Ntk_t * pNtkNew = NULL;
+    Vec_Ptr_t * vCritical;
+    Vec_Int_t * vValues;
+    Abc_Obj_t * pObj;
+    int i, k, IterBest, DelayCur, DelayBest, DelayStart, LatchesBest;
+    // transfer intitial values
+    if ( fInitial )
+    {
+        if ( fForward )
+            Abc_NtkRetimeTranferToCopy( pNtk );
+        else
+        {
+            // save initial value of the latches
+            vValues = Abc_NtkRetimeCollectLatchValues( pNtk );
+            // start the network for initial value computation
+            pNtkNew = Abc_NtkRetimeBackwardInitialStart( pNtk );
+        }
+    }
+
+if ( fVerbose && !fInitial )
+    printf( "Performing analysis:\n" );
+    // find the best iteration
+    DelayBest = ABC_INFINITY; IterBest = 0; LatchesBest = Abc_NtkLatchNum(pNtk);
+    vCritical = Vec_PtrAlloc( 100 );
+    for ( i = 0; ; i++ )
+    {
+        // perform moves for the timing-critical nodes
+        DelayCur = Abc_NtkRetimeTiming( pNtk, fForward, vCritical );
+        if ( i == 0 )
+            DelayStart = DelayCur;
+        // record this position if it has the best delay
+        if ( DelayBest > DelayCur )
+        {
+if ( fVerbose && !fInitial )
+    printf( "%s Iter = %3d. Delay = %3d. Latches = %5d. Delta = %6.2f. Ratio = %4.2f %%\n", 
+        fForward ? "Fwd": "Bwd", i, DelayCur, Abc_NtkLatchNum(pNtk), 
+        1.0*(Abc_NtkLatchNum(pNtk)-LatchesBest)/(DelayBest-DelayCur), 
+        100.0*(Abc_NtkLatchNum(pNtk)-LatchesBest)/Abc_NtkLatchNum(pNtk)/(DelayBest-DelayCur) );
+
+            DelayBest = DelayCur;
+            IterBest = i;
+            LatchesBest = Abc_NtkLatchNum(pNtk);
+        }
+        // quit after timing analysis
+        if ( i == nIterLimit )
+            break;
+        // skip if 10 interations did not give improvement
+        if ( i - IterBest > 20 )
+            break;
+        // try retiming to improve the delay
+        Vec_PtrForEachEntry( vCritical, pObj, k )
+            if ( Abc_NtkRetimeNodeIsEnabled(pObj, fForward) )
+                Abc_NtkRetimeNode( pObj, fForward, fInitial );
+        // share latches
+        if ( !fForward )
+            Abc_NtkRetimeShareLatches( pNtk, fInitial );    
+    }
+    Vec_PtrFree( vCritical );
+    // transfer the initial state back to the latches
+    if ( fInitial )
+    {
+        if ( fForward )
+            Abc_NtkRetimeTranferFromCopy( pNtk );
+        else
+        {
+            Abc_NtkRetimeBackwardInitialFinish( pNtk, pNtkNew, vValues, fVerbose );
+            Abc_NtkDelete( pNtkNew );
+            Vec_IntFree( vValues );
+        }
+    }
+if ( fVerbose && !fInitial )
+    printf( "%s : Starting delay = %3d.  Final delay = %3d.  IterBest = %2d (out of %2d).\n", 
+        fForward? "Forward " : "Backward", DelayStart, DelayBest, IterBest, nIterLimit );
+    *pIterBest = (nIterLimit == 1) ? 1 : IterBest;
+    return DelayBest;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the set of timing-critical nodes.]
+
+  Description [Performs static timing analysis on the network. Uses 
+  unit-delay model.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeTiming( Abc_Ntk_t * pNtk, int fForward, Vec_Ptr_t * vCritical )
+{
+    Vec_Ptr_t * vLatches;
+    Abc_Obj_t * pObj, * pNext;
+    int i, k, LevelCur, LevelMax = 0;
+    // mark all objects except nodes
+    Abc_NtkIncrementTravId(pNtk);
+    vLatches = Vec_PtrAlloc( Abc_NtkLatchNum(pNtk) );
+    Abc_NtkForEachObj( pNtk, pObj, i )
+    {
+        if ( Abc_ObjIsLatch(pObj) )
+            Vec_PtrPush( vLatches, pObj );
+        if ( Abc_ObjIsNode(pObj) )
+            continue;
+        pObj->Level = 0;
+        Abc_NodeSetTravIdCurrent( pObj );
+    }
+    // perform analysis from CIs/COs
+    if ( fForward )
+    {
+        Vec_PtrForEachEntry( vLatches, pObj, i )
+        {
+            Abc_ObjForEachFanout( pObj, pNext, k )
+            {
+                LevelCur = Abc_NtkRetimeTiming_rec( pNext, fForward );
+                if ( LevelMax < LevelCur )
+                    LevelMax = LevelCur;
+            }
+        }
+        Abc_NtkForEachPi( pNtk, pObj, i )
+        {
+            Abc_ObjForEachFanout( pObj, pNext, k )
+            {
+                LevelCur = Abc_NtkRetimeTiming_rec( pNext, fForward );
+                if ( LevelMax < LevelCur )
+                    LevelMax = LevelCur;
+            }
+        }
+    }
+    else
+    {
+        Vec_PtrForEachEntry( vLatches, pObj, i )
+        {
+            LevelCur = Abc_NtkRetimeTiming_rec( Abc_ObjFanin0(pObj), fForward );
+            if ( LevelMax < LevelCur )
+                LevelMax = LevelCur;
+        }
+        Abc_NtkForEachPo( pNtk, pObj, i )
+        {
+            LevelCur = Abc_NtkRetimeTiming_rec( Abc_ObjFanin0(pObj), fForward );
+            if ( LevelMax < LevelCur )
+                LevelMax = LevelCur;
+        }
+    }
+    // collect timing critical nodes, which should be retimed forward/backward
+    Vec_PtrClear( vCritical );
+    Abc_NtkIncrementTravId(pNtk);
+    if ( fForward )
+    {
+        Vec_PtrForEachEntry( vLatches, pObj, i )
+        {
+            Abc_ObjForEachFanout( pObj, pNext, k )
+            {
+                if ( Abc_NodeIsTravIdCurrent(pNext) )
+                    continue;
+                if ( LevelMax != (int)pNext->Level )
+                    continue;
+                // new critical node
+                Vec_PtrPush( vCritical, pNext );
+                Abc_NodeSetTravIdCurrent( pNext );
+            }
+        }
+    }
+    else
+    {
+        Vec_PtrForEachEntry( vLatches, pObj, i )
+        {
+            Abc_ObjForEachFanin( pObj, pNext, k )
+            {
+                if ( Abc_NodeIsTravIdCurrent(pNext) )
+                    continue;
+                if ( LevelMax != (int)pNext->Level )
+                    continue;
+                // new critical node
+                Vec_PtrPush( vCritical, pNext );
+                Abc_NodeSetTravIdCurrent( pNext );
+            }
+        }
+    }
+    Vec_PtrFree( vLatches );
+    return LevelMax;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively performs timing analysis.]
+
+  Description [Performs static timing analysis on the network. Uses 
+  unit-delay model.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeTiming_rec( Abc_Obj_t * pObj, int fForward )
+{
+    Abc_Obj_t * pNext;
+    int i, LevelCur, LevelMax = 0;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return pObj->Level;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // visit the next nodes
+    if ( fForward )
+    {
+        Abc_ObjForEachFanout( pObj, pNext, i )
+        {
+            LevelCur = Abc_NtkRetimeTiming_rec( pNext, fForward );
+            if ( LevelMax < LevelCur )
+                LevelMax = LevelCur;
+        }
+    }
+    else
+    {
+        Abc_ObjForEachFanin( pObj, pNext, i )
+        {
+            LevelCur = Abc_NtkRetimeTiming_rec( pNext, fForward );
+            if ( LevelMax < LevelCur )
+                LevelMax = LevelCur;
+        }
+    }
+//    printf( "Node %3d -> Level %3d.\n", pObj->Id, LevelMax + 1 );
+    pObj->Level = LevelMax + 1;
+    return pObj->Level;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/retFlow.c b/src/opt/ret/retFlow.c
new file mode 100644
index 00000000..47ee8516
--- /dev/null
+++ b/src/opt/ret/retFlow.c
@@ -0,0 +1,783 @@
+/**CFile****************************************************************
+
+  FileName    [retFlow.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Implementation of maximum flow (min-area retiming).]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retFlow.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static inline int         Abc_ObjSetPath( Abc_Obj_t * pObj, Abc_Obj_t * pNext ) { pObj->pCopy = pNext; return 1;   }
+static inline Abc_Obj_t * Abc_ObjGetPath( Abc_Obj_t * pObj )                    { return pObj->pCopy;              }
+static inline Abc_Obj_t * Abc_ObjGetFanoutPath( Abc_Obj_t * pObj ) 
+{ 
+    Abc_Obj_t * pFanout;
+    int i;
+    assert( Abc_ObjGetPath(pObj) ); 
+    Abc_ObjForEachFanout( pObj, pFanout, i )
+        if ( Abc_ObjGetPath(pFanout) == pObj )
+            return pFanout;
+    return NULL;
+}
+static inline Abc_Obj_t * Abc_ObjGetFaninPath( Abc_Obj_t * pObj ) 
+{ 
+    Abc_Obj_t * pFanin;
+    int i;
+    assert( Abc_ObjGetPath(pObj) ); 
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+        if ( Abc_ObjGetPath(pFanin) == pObj )
+            return pFanin;
+    return NULL;
+}
+static inline Abc_Obj_t * Abc_ObjGetPredecessorBwd( Abc_Obj_t * pObj ) 
+{ 
+    Abc_Obj_t * pNext;
+    int i;
+    Abc_ObjForEachFanout( pObj, pNext, i )
+        if ( Abc_ObjGetPath(pNext) == pObj )
+            return pNext;
+    Abc_ObjForEachFanin( pObj, pNext, i )
+        if ( Abc_ObjGetPath(pNext) == pObj )
+            return pNext;
+    return NULL;
+}
+static inline Abc_Obj_t * Abc_ObjGetPredecessorFwd( Abc_Obj_t * pObj ) 
+{ 
+    Abc_Obj_t * pNext;
+    int i;
+    Abc_ObjForEachFanin( pObj, pNext, i )
+        if ( Abc_ObjGetPath(pNext) == pObj )
+            return pNext;
+    Abc_ObjForEachFanout( pObj, pNext, i )
+        if ( Abc_ObjGetPath(pNext) == pObj )
+            return pNext;
+    return NULL;
+}
+
+static int         Abc_NtkMaxFlowBwdPath_rec( Abc_Obj_t * pObj );
+static int         Abc_NtkMaxFlowFwdPath_rec( Abc_Obj_t * pObj );
+static int         Abc_NtkMaxFlowBwdPath2_rec( Abc_Obj_t * pObj );
+static int         Abc_NtkMaxFlowFwdPath2_rec( Abc_Obj_t * pObj );
+//static int         Abc_NtkMaxFlowBwdPath3_rec( Abc_Obj_t * pObj );
+static int         Abc_NtkMaxFlowFwdPath3_rec( Abc_Obj_t * pObj, Abc_Obj_t * pPrev, int fFanin );
+static Vec_Ptr_t * Abc_NtkMaxFlowMinCut( Abc_Ntk_t * pNtk, int fForward );
+static void        Abc_NtkMaxFlowMinCutUpdate( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut, int fForward );
+static int         Abc_NtkMaxFlowVerifyCut( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut, int fForward );
+static void        Abc_NtkMaxFlowPrintCut( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut );
+static void        Abc_NtkMaxFlowPrintFlow( Abc_Ntk_t * pNtk, int fForward );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Test-bench for the max-flow computation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkMaxFlowTest( Abc_Ntk_t * pNtk )
+{
+    Vec_Ptr_t * vMinCut;
+    Abc_Obj_t * pObj;
+    int i;
+
+    // forward flow
+    Abc_NtkForEachPo( pNtk, pObj, i )
+        pObj->fMarkA = 1;
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        pObj->fMarkA = Abc_ObjFanin0(pObj)->fMarkA = 1;
+//        Abc_ObjFanin0(pObj)->fMarkA = 1;
+    vMinCut = Abc_NtkMaxFlow( pNtk, 1, 1 );
+    Vec_PtrFree( vMinCut );
+    Abc_NtkCleanMarkA( pNtk );
+
+    // backward flow
+    Abc_NtkForEachPi( pNtk, pObj, i )
+        pObj->fMarkA = 1;
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        pObj->fMarkA = Abc_ObjFanout0(pObj)->fMarkA = 1;
+//        Abc_ObjFanout0(pObj)->fMarkA = 1;
+    vMinCut = Abc_NtkMaxFlow( pNtk, 0, 1 );
+    Vec_PtrFree( vMinCut );
+    Abc_NtkCleanMarkA( pNtk );
+
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implementation of max-flow/min-cut computation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Abc_NtkMaxFlow( Abc_Ntk_t * pNtk, int fForward, int fVerbose )
+{
+    Vec_Ptr_t * vMinCut;
+    Abc_Obj_t * pLatch;
+    int Flow, FlowCur, RetValue, i;
+    int clk = clock();
+    int fUseDirectedFlow = 1;
+
+    // find the max-flow
+    Abc_NtkCleanCopy( pNtk );
+    Flow = 0;
+    Abc_NtkIncrementTravId(pNtk);
+    Abc_NtkForEachLatch( pNtk, pLatch, i )
+    {
+        if ( fForward )
+        {
+//            assert( !Abc_ObjFanout0(pLatch)->fMarkA );
+            FlowCur  = Abc_NtkMaxFlowFwdPath2_rec( Abc_ObjFanout0(pLatch) );
+//            FlowCur  = Abc_NtkMaxFlowFwdPath3_rec( Abc_ObjFanout0(pLatch), pLatch, 1 );
+            Flow    += FlowCur;
+        }
+        else
+        {
+            assert( !Abc_ObjFanin0(pLatch)->fMarkA );
+            FlowCur  = Abc_NtkMaxFlowBwdPath2_rec( Abc_ObjFanin0(pLatch) );
+            Flow    += FlowCur;
+        }
+        if ( FlowCur )
+            Abc_NtkIncrementTravId(pNtk);
+    }
+
+    if ( !fUseDirectedFlow )
+    {
+        Abc_NtkIncrementTravId(pNtk);
+        Abc_NtkForEachLatch( pNtk, pLatch, i )
+        {
+            if ( fForward )
+            {
+    //            assert( !Abc_ObjFanout0(pLatch)->fMarkA );
+                FlowCur  = Abc_NtkMaxFlowFwdPath_rec( Abc_ObjFanout0(pLatch) );
+                Flow    += FlowCur;
+            }
+            else
+            {
+                assert( !Abc_ObjFanin0(pLatch)->fMarkA );
+                FlowCur  = Abc_NtkMaxFlowBwdPath_rec( Abc_ObjFanin0(pLatch) );
+                Flow    += FlowCur;
+            }
+            if ( FlowCur )
+                Abc_NtkIncrementTravId(pNtk);
+        }
+    }
+//    Abc_NtkMaxFlowPrintFlow( pNtk, fForward );
+
+    // mark the nodes reachable from the latches
+    Abc_NtkIncrementTravId(pNtk);
+    Abc_NtkForEachLatch( pNtk, pLatch, i )
+    {
+        if ( fForward )
+        {
+//            assert( !Abc_ObjFanout0(pLatch)->fMarkA );
+            if ( fUseDirectedFlow )
+                RetValue = Abc_NtkMaxFlowFwdPath2_rec( Abc_ObjFanout0(pLatch) );
+//                RetValue = Abc_NtkMaxFlowFwdPath3_rec( Abc_ObjFanout0(pLatch), pLatch, 1 );
+            else
+                RetValue = Abc_NtkMaxFlowFwdPath_rec( Abc_ObjFanout0(pLatch) );
+        }
+        else
+        {
+            assert( !Abc_ObjFanin0(pLatch)->fMarkA );
+            if ( fUseDirectedFlow )
+                RetValue = Abc_NtkMaxFlowBwdPath2_rec( Abc_ObjFanin0(pLatch) );
+            else
+                RetValue = Abc_NtkMaxFlowBwdPath_rec( Abc_ObjFanin0(pLatch) );
+        }
+        assert( RetValue == 0 );
+    }
+
+    // find the min-cut with the smallest volume
+    vMinCut = Abc_NtkMaxFlowMinCut( pNtk, fForward );
+    // verify the cut
+    if ( !Abc_NtkMaxFlowVerifyCut(pNtk, vMinCut, fForward) )
+        printf( "Abc_NtkMaxFlow() error! The computed min-cut is not a cut!\n" );
+    // make the cut retimable
+    Abc_NtkMaxFlowMinCutUpdate( pNtk, vMinCut, fForward );
+
+    // report the results
+    if ( fVerbose )
+    {
+    printf( "L = %6d. %s max-flow = %6d.  Min-cut = %6d.  ", 
+        Abc_NtkLatchNum(pNtk), fForward? "Forward " : "Backward", Flow, Vec_PtrSize(vMinCut) );
+PRT( "Time", clock() - clk );
+    }
+
+//    Abc_NtkMaxFlowPrintCut( pNtk, vMinCut );
+    return vMinCut;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Tries to find an augmenting path originating in this node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkMaxFlowBwdPath_rec( Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pNext, * pPred;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return 0;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // get the predecessor
+    pPred = Abc_ObjGetPredecessorBwd( pObj );
+    // process node without flow
+    if ( !Abc_ObjGetPath(pObj) )
+    {
+        // start the path if we reached a terminal node
+        if ( pObj->fMarkA )
+            return Abc_ObjSetPath( pObj, (void *)1 );
+        // explore the fanins
+        Abc_ObjForEachFanin( pObj, pNext, i )
+            if ( pNext != pPred && !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowBwdPath_rec(pNext) )
+                return Abc_ObjSetPath( pObj, pNext );
+        Abc_ObjForEachFanout( pObj, pNext, i )
+            if ( pNext != pPred && !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowBwdPath_rec(pNext) )
+                return Abc_ObjSetPath( pObj, pNext );
+        return 0;
+    }
+    // pObj has flow - find the fanout with flow
+    if ( pPred == NULL )
+        return 0;
+    // go through the successors of the predecessor
+    Abc_ObjForEachFanin( pPred, pNext, i )
+        if ( !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowBwdPath_rec( pNext ) )
+            return Abc_ObjSetPath( pPred, pNext );
+    Abc_ObjForEachFanout( pPred, pNext, i )
+        if ( !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowBwdPath_rec( pNext ) )
+            return Abc_ObjSetPath( pPred, pNext );
+    // try the fanout
+    if ( Abc_NtkMaxFlowBwdPath_rec( pPred ) )
+        return Abc_ObjSetPath( pPred, NULL );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Tries to find an augmenting path originating in this node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkMaxFlowFwdPath_rec( Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pNext, * pPred;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return 0;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // get the predecessor
+    pPred = Abc_ObjGetPredecessorFwd( pObj );
+    // process node without flow
+    if ( !Abc_ObjGetPath(pObj) )
+    {
+        // start the path if we reached a terminal node
+        if ( pObj->fMarkA )
+            return Abc_ObjSetPath( pObj, (void *)1 );
+        // explore the fanins
+        Abc_ObjForEachFanout( pObj, pNext, i )
+            if ( pNext != pPred && !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowFwdPath_rec(pNext) )
+                return Abc_ObjSetPath( pObj, pNext );
+        Abc_ObjForEachFanin( pObj, pNext, i )
+            if ( pNext != pPred && !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowFwdPath_rec(pNext) )
+                return Abc_ObjSetPath( pObj, pNext );
+        return 0;
+    }
+    // pObj has flow - find the fanout with flow
+    if ( pPred == NULL )
+        return 0;
+    // go through the successors of the predecessor
+    Abc_ObjForEachFanout( pPred, pNext, i )
+        if ( !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowFwdPath_rec( pNext ) )
+            return Abc_ObjSetPath( pPred, pNext );
+    Abc_ObjForEachFanin( pPred, pNext, i )
+        if ( !Abc_ObjIsLatch(pNext) && Abc_NtkMaxFlowFwdPath_rec( pNext ) )
+            return Abc_ObjSetPath( pPred, pNext );
+    // try the fanout
+    if ( Abc_NtkMaxFlowFwdPath_rec( pPred ) )
+        return Abc_ObjSetPath( pPred, NULL );
+    return 0;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Tries to find an augmenting path originating in this edge.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkMaxFlowFwdPath3_rec( Abc_Obj_t * pObj, Abc_Obj_t * pPrev, int fFanin )
+{
+    Abc_Obj_t * pFanin, * pFanout;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return 0;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // skip the fanin which already has flow
+    if ( fFanin && Abc_ObjGetPath(pPrev) )
+        return 0;
+    // if the node has no flow, try to push through the fanouts
+    if ( !Abc_ObjGetPath(pObj) )
+    {
+        // start the path if we reached a terminal node
+        if ( pObj->fMarkA )
+            return Abc_ObjSetPath( pObj, (void *)1 );
+        // try to push flow through the fanouts
+        Abc_ObjForEachFanout( pObj, pFanout, i )
+            if ( Abc_NtkMaxFlowFwdPath3_rec(pFanout, pObj, 1) )
+                return fFanin? Abc_ObjSetPath(pPrev, pObj) : 1;
+    }
+    // try to push through the fanins
+    Abc_ObjForEachFanin( pObj, pFanin, i )
+        if ( !Abc_ObjIsLatch(pFanin) && Abc_NtkMaxFlowFwdPath3_rec(pFanin, pObj, 0) )
+            return Abc_ObjSetPath( pFanin, NULL );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Tries to find an augmenting path originating in this node.]
+
+  Description [This procedure works for directed graphs only!]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkMaxFlowBwdPath2_rec( Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pFanout, * pFanin;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return 0;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // process node without flow
+    if ( !Abc_ObjGetPath(pObj) )
+    {
+        // start the path if we reached a terminal node
+        if ( pObj->fMarkA )
+            return Abc_ObjSetPath( pObj, (void *)1 );
+        // explore the fanins
+        Abc_ObjForEachFanin( pObj, pFanin, i )
+            if ( Abc_NtkMaxFlowBwdPath2_rec(pFanin) )
+                return Abc_ObjSetPath( pObj, pFanin );
+        return 0;
+    }
+    // pObj has flow - find the fanout with flow
+    pFanout = Abc_ObjGetFanoutPath( pObj );
+    if ( pFanout == NULL )
+        return 0;
+    // go through the fanins of the fanout with flow
+    Abc_ObjForEachFanin( pFanout, pFanin, i )
+        if ( Abc_NtkMaxFlowBwdPath2_rec( pFanin ) )
+            return Abc_ObjSetPath( pFanout, pFanin );
+    // try the fanout
+    if ( Abc_NtkMaxFlowBwdPath2_rec( pFanout ) )
+        return Abc_ObjSetPath( pFanout, NULL );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Tries to find an augmenting path originating in this node.]
+
+  Description [This procedure works for directed graphs only!]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkMaxFlowFwdPath2_rec( Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pFanout, * pFanin;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return 0;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // process node without flow
+    if ( !Abc_ObjGetPath(pObj) )
+    { 
+        // start the path if we reached a terminal node
+        if ( pObj->fMarkA )
+            return Abc_ObjSetPath( pObj, (void *)1 );
+        // explore the fanins
+        Abc_ObjForEachFanout( pObj, pFanout, i )
+            if ( Abc_NtkMaxFlowFwdPath2_rec(pFanout) )
+                return Abc_ObjSetPath( pObj, pFanout );
+        return 0;
+    }
+    // pObj has flow - find the fanout with flow
+    pFanin = Abc_ObjGetFaninPath( pObj );
+    if ( pFanin == NULL )
+        return 0;
+    // go through the fanins of the fanout with flow
+    Abc_ObjForEachFanout( pFanin, pFanout, i )
+        if ( Abc_NtkMaxFlowFwdPath2_rec( pFanout ) )
+            return Abc_ObjSetPath( pFanin, pFanout );
+    // try the fanout
+    if ( Abc_NtkMaxFlowFwdPath2_rec( pFanin ) )
+        return Abc_ObjSetPath( pFanin, NULL );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find minimum-volume minumum cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Abc_NtkMaxFlowMinCut( Abc_Ntk_t * pNtk, int fForward )
+{
+    Vec_Ptr_t * vMinCut;
+    Abc_Obj_t * pObj;
+    int i;
+    // collect the cut nodes
+    vMinCut = Vec_PtrAlloc( Abc_NtkLatchNum(pNtk) );
+    Abc_NtkForEachObj( pNtk, pObj, i )
+    {
+        // node without flow is not a cut node
+        if ( !Abc_ObjGetPath(pObj) )
+            continue;
+        // unvisited node is below the cut
+        if ( !Abc_NodeIsTravIdCurrent(pObj) )
+            continue;
+        // add terminal with flow or node whose path is not visited
+        if ( pObj->fMarkA || !Abc_NodeIsTravIdCurrent( Abc_ObjGetPath(pObj) ) )
+            Vec_PtrPush( vMinCut, pObj );
+    }
+    return vMinCut;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Marks the TFI cone with MarkA.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkMaxFlowMarkCut_rec( Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pNext;
+    int i;
+    if ( pObj->fMarkA )
+        return;
+    pObj->fMarkA = 1;
+    Abc_ObjForEachFanin( pObj, pNext, i )
+        Abc_NtkMaxFlowMarkCut_rec( pNext );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Visits the TFI up to marked nodes and collects marked nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkMaxFlowCollectCut_rec( Abc_Obj_t * pObj, Vec_Ptr_t * vNodes )
+{
+    Abc_Obj_t * pNext;
+    int i;
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return;
+    Abc_NodeSetTravIdCurrent(pObj);
+    if ( pObj->fMarkA )
+    {
+        Vec_PtrPush( vNodes, pObj );
+        return;
+    }
+    Abc_ObjForEachFanin( pObj, pNext, i )
+        Abc_NtkMaxFlowCollectCut_rec( pNext, vNodes );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Updates the minimum cut to be retimable.]
+
+  Description [This procedure also labels the nodes reachable from
+  the latches to the cut with fMarkA.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkMaxFlowMinCutUpdate( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut, int fForward )
+{
+    Abc_Obj_t * pObj, * pNext;
+    int i, k;
+    // clean marks
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        pObj->fMarkA = 0;
+    // set latch outputs
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        Abc_ObjFanout0(pObj)->fMarkA = 1;
+    // traverse from cut nodes
+    Vec_PtrForEachEntry( vMinCut, pObj, i )
+        Abc_NtkMaxFlowMarkCut_rec( pObj );
+    if ( fForward )
+    {
+        // change mincut to be nodes with unmarked fanouts
+        Vec_PtrClear( vMinCut );
+        Abc_NtkForEachObj( pNtk, pObj, i )
+        {
+            if ( !pObj->fMarkA )
+                continue;
+            Abc_ObjForEachFanout( pObj, pNext, k )
+            {
+                if ( pNext->fMarkA )
+                    continue;
+                Vec_PtrPush( vMinCut, pObj );
+                break;
+            }
+        }
+    }
+    else
+    {
+        // change mincut to be marked fanins of the unmarked nodes
+        Vec_PtrClear( vMinCut );
+        Abc_NtkIncrementTravId(pNtk);
+        Abc_NtkForEachLatch( pNtk, pObj, i )
+            Abc_NtkMaxFlowCollectCut_rec( Abc_ObjFanin0(pObj), vMinCut );
+        // transfer the attribute
+        Abc_NtkForEachObj( pNtk, pObj, i )
+            pObj->fMarkA = Abc_NodeIsTravIdCurrent(pObj);
+        // unmark the cut nodes
+        Vec_PtrForEachEntry( vMinCut, pObj, i )
+            pObj->fMarkA = 0;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies the min-cut is indeed a cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkMaxFlowVerifyCut_rec( Abc_Obj_t * pObj, int fForward )
+{
+    Abc_Obj_t * pNext;
+    int i;
+    // skip visited nodes
+    if ( Abc_NodeIsTravIdCurrent(pObj) )
+        return 1;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // visit the node
+    if ( fForward )
+    {
+        if ( Abc_ObjIsCo(pObj) )
+            return 0;
+        // explore the fanouts
+        Abc_ObjForEachFanout( pObj, pNext, i )
+            if ( !Abc_NtkMaxFlowVerifyCut_rec(pNext, fForward) )
+                return 0;
+    }
+    else
+    {
+        if ( Abc_ObjIsCi(pObj) )
+            return 0;
+        // explore the fanins
+        Abc_ObjForEachFanin( pObj, pNext, i )
+            if ( !Abc_NtkMaxFlowVerifyCut_rec(pNext, fForward) )
+                return 0;
+    }
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies the min-cut is indeed a cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkMaxFlowVerifyCut( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut, int fForward )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    // mark the cut with the current traversal ID
+    Abc_NtkIncrementTravId(pNtk);
+    Vec_PtrForEachEntry( vMinCut, pObj, i )
+        Abc_NodeSetTravIdCurrent( pObj );
+    // search from the latches for a path to the COs/CIs
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+    {
+        if ( fForward )
+        {
+            if ( !Abc_NtkMaxFlowVerifyCut_rec( Abc_ObjFanout0(pObj), fForward ) )
+                return 0;
+        }
+        else
+        {
+            if ( !Abc_NtkMaxFlowVerifyCut_rec( Abc_ObjFanin0(pObj), fForward ) )
+                return 0;
+        }
+    }
+/*
+    {
+        // count the volume of the cut
+        int Counter = 0;
+        Abc_NtkForEachObj( pNtk, pObj, i )
+            Counter += Abc_NodeIsTravIdCurrent( pObj );
+        printf( "Volume = %d.\n", Counter );
+    }
+*/
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the flows.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkMaxFlowPrintFlow( Abc_Ntk_t * pNtk, int fForward )
+{
+    Abc_Obj_t * pLatch, * pNext, * pPrev;
+    int i;
+    if ( fForward )
+    {
+        Vec_PtrForEachEntry( pNtk->vBoxes, pLatch, i )
+        {
+            assert( !Abc_ObjFanout0(pLatch)->fMarkA );
+            if ( Abc_ObjGetPath(Abc_ObjFanout0(pLatch)) == NULL ) // no flow through this latch
+                continue;
+            printf( "Path = " );
+            for ( pNext = Abc_ObjFanout0(pLatch); pNext != (void *)1; pNext = Abc_ObjGetPath(pNext) )
+            {
+                printf( "%s(%d) ", Abc_ObjName(pNext), pNext->Id );
+                pPrev = pNext;
+            }
+            if ( !Abc_ObjIsPo(pPrev) )
+            printf( "%s(%d) ", Abc_ObjName(Abc_ObjFanout0(pPrev)), Abc_ObjFanout0(pPrev)->Id );
+            printf( "\n" );
+        }
+    }
+    else
+    {
+        Vec_PtrForEachEntry( pNtk->vBoxes, pLatch, i )
+        {
+            assert( !Abc_ObjFanin0(pLatch)->fMarkA );
+            if ( Abc_ObjGetPath(Abc_ObjFanin0(pLatch)) == NULL ) // no flow through this latch
+                continue;
+            printf( "Path = " );
+            for ( pNext = Abc_ObjFanin0(pLatch); pNext != (void *)1; pNext = Abc_ObjGetPath(pNext) )
+            {
+                printf( "%s(%d) ", Abc_ObjName(pNext), pNext->Id );
+                pPrev = pNext;
+            }
+            if ( !Abc_ObjIsPi(pPrev) )
+            printf( "%s(%d) ", Abc_ObjName(Abc_ObjFanin0(pPrev)), Abc_ObjFanin0(pPrev)->Id );
+            printf( "\n" );
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the min-cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkMaxFlowPrintCut( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMinCut )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    printf( "Min-cut: " );
+    Vec_PtrForEachEntry( vMinCut, pObj, i )
+        printf( "%s(%d) ", Abc_ObjName(pObj), pObj->Id );
+    printf( "\n" );
+    printf( "Marked nodes: " );
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( pObj->fMarkA )
+            printf( "%s(%d) ", Abc_ObjName(pObj), pObj->Id );
+    printf( "\n" );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/retIncrem.c b/src/opt/ret/retIncrem.c
new file mode 100644
index 00000000..ba8104be
--- /dev/null
+++ b/src/opt/ret/retIncrem.c
@@ -0,0 +1,464 @@
+/**CFile****************************************************************
+
+  FileName    [retIncrem.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    [Incremental retiming in one direction.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retIncrem.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Abc_NtkRetimeOneWay( Abc_Ntk_t * pNtk, int fForward, int fVerbose );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs retiming in one direction.]
+
+  Description [Currently does not retime over black boxes.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeIncremental( Abc_Ntk_t * pNtk, int fForward, int fMinDelay, int fOneStep, int fVerbose )
+{
+    Abc_Ntk_t * pNtkCopy = NULL;
+    Vec_Ptr_t * vBoxes;
+    st_table * tLatches;
+    int nLatches = Abc_NtkLatchNum(pNtk);
+    int nIdMaxStart = Abc_NtkObjNumMax(pNtk);
+    int RetValue, nIterLimit;
+    if ( Abc_NtkNodeNum(pNtk) == 0 )
+        return 0;
+    // reorder CI/CO/latch inputs
+    Abc_NtkOrderCisCos( pNtk );
+    if ( fMinDelay ) 
+    {
+        nIterLimit = fOneStep? 1 : 2 * Abc_NtkLevel(pNtk);
+        pNtkCopy = Abc_NtkDup( pNtk );
+        tLatches = Abc_NtkRetimePrepareLatches( pNtkCopy );
+        st_free_table( tLatches );
+    }
+    // collect latches and remove CIs/COs
+    tLatches = Abc_NtkRetimePrepareLatches( pNtk );
+    // share the latches
+    Abc_NtkRetimeShareLatches( pNtk, 0 );    
+    // save boxes
+    vBoxes = pNtk->vBoxes;  pNtk->vBoxes = NULL;
+    // perform the retiming
+    if ( fMinDelay )
+        Abc_NtkRetimeMinDelay( pNtk, pNtkCopy, nIterLimit, fForward, fVerbose );
+    else
+        Abc_NtkRetimeOneWay( pNtk, fForward, fVerbose );
+    if ( fMinDelay ) 
+        Abc_NtkDelete( pNtkCopy );
+    // share the latches
+    Abc_NtkRetimeShareLatches( pNtk, 0 );    
+    // restore boxes
+    pNtk->vBoxes = vBoxes;
+    // finalize the latches
+    RetValue = Abc_NtkRetimeFinalizeLatches( pNtk, tLatches, nIdMaxStart );
+    st_free_table( tLatches );
+    if ( RetValue == 0 )
+        return 0;
+    // fix the COs
+//    Abc_NtkLogicMakeSimpleCos( pNtk, 0 );
+    // check for correctness
+    if ( !Abc_NtkCheck( pNtk ) )
+        fprintf( stdout, "Abc_NtkRetimeForward(): Network check has failed.\n" );
+    // return the number of latches saved
+    return nLatches - Abc_NtkLatchNum(pNtk);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prepares the network for retiming.]
+
+  Description [Hash latches into their number in the original network.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+st_table * Abc_NtkRetimePrepareLatches( Abc_Ntk_t * pNtk )
+{
+    st_table * tLatches;
+    Abc_Obj_t * pLatch, * pLatchIn, * pLatchOut, * pFanin;
+    int i, nOffSet = Abc_NtkBoxNum(pNtk) - Abc_NtkLatchNum(pNtk);
+    // collect latches and remove CIs/COs
+    tLatches = st_init_table( st_ptrcmp, st_ptrhash );
+    Abc_NtkForEachLatch( pNtk, pLatch, i )
+    {
+        // map latch into its true number
+        st_insert( tLatches, (void *)pLatch, (void *)(i-nOffSet) );
+        // disconnect LI     
+        pLatchIn = Abc_ObjFanin0(pLatch);
+        pFanin = Abc_ObjFanin0(pLatchIn);
+        Abc_ObjTransferFanout( pLatchIn, pFanin );
+        Abc_ObjDeleteFanin( pLatchIn, pFanin );
+        // disconnect LO     
+        pLatchOut = Abc_ObjFanout0(pLatch);
+        pFanin = Abc_ObjFanin0(pLatchOut);
+        if ( Abc_ObjFanoutNum(pLatchOut) > 0 )
+            Abc_ObjTransferFanout( pLatchOut, pFanin );
+        Abc_ObjDeleteFanin( pLatchOut, pFanin );
+    }
+    return tLatches;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finalizes the latches after retiming.]
+
+  Description [Reuses the LIs/LOs for old latches.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeFinalizeLatches( Abc_Ntk_t * pNtk, st_table * tLatches, int nIdMaxStart )
+{
+    Vec_Ptr_t * vCisOld, * vCosOld, * vBoxesOld, * vCisNew, * vCosNew, * vBoxesNew;
+    Abc_Obj_t * pObj, * pLatch, * pLatchIn, * pLatchOut;
+    int i, Index;
+    // create new arrays
+    vCisOld   = pNtk->vCis;    pNtk->vCis   = NULL;  vCisNew   = Vec_PtrAlloc( 100 );
+    vCosOld   = pNtk->vCos;    pNtk->vCos   = NULL;  vCosNew   = Vec_PtrAlloc( 100 );  
+    vBoxesOld = pNtk->vBoxes;  pNtk->vBoxes = NULL;  vBoxesNew = Vec_PtrAlloc( 100 );
+    // copy boxes and their CIs/COs
+    Vec_PtrForEachEntryStop( vCisOld, pObj, i, Vec_PtrSize(vCisOld) - st_count(tLatches) )
+        Vec_PtrPush( vCisNew, pObj );
+    Vec_PtrForEachEntryStop( vCosOld, pObj, i, Vec_PtrSize(vCosOld) - st_count(tLatches) )
+        Vec_PtrPush( vCosNew, pObj );
+    Vec_PtrForEachEntryStop( vBoxesOld, pObj, i, Vec_PtrSize(vBoxesOld) - st_count(tLatches) )
+        Vec_PtrPush( vBoxesNew, pObj );
+    // go through the latches
+    Abc_NtkForEachObj( pNtk, pLatch, i )
+    {
+        if ( !Abc_ObjIsLatch(pLatch) )
+            continue;
+        if ( Abc_ObjId(pLatch) >= (unsigned)nIdMaxStart )
+        {
+            // this is a new latch 
+            pLatchIn  = Abc_NtkCreateBi(pNtk);
+            pLatchOut = Abc_NtkCreateBo(pNtk);
+            Abc_ObjAssignName( pLatchOut, Abc_ObjName(pLatch), "_out" );
+            Abc_ObjAssignName( pLatchIn,  Abc_ObjName(pLatch), "_in" );
+        }
+        else
+        {
+            // this is an old latch 
+            // get its number in the original order
+            if ( !st_lookup( tLatches, (char *)pLatch, (char **)&Index ) )
+            {
+                printf( "Abc_NtkRetimeFinalizeLatches(): Internal error.\n" );
+                return 0;
+            }
+            assert( pLatch == Vec_PtrEntry(vBoxesOld, Vec_PtrSize(vBoxesOld) - st_count(tLatches) + Index) );
+            // reconnect with the old LIs/LOs
+            pLatchIn  = Vec_PtrEntry( vCosOld, Vec_PtrSize(vCosOld) - st_count(tLatches) + Index );
+            pLatchOut = Vec_PtrEntry( vCisOld, Vec_PtrSize(vCisOld) - st_count(tLatches) + Index );
+        }
+        // connect
+        Abc_ObjAddFanin( pLatchIn, Abc_ObjFanin0(pLatch) );
+        Abc_ObjPatchFanin( pLatch, Abc_ObjFanin0(pLatch), pLatchIn );
+        if ( Abc_ObjFanoutNum(pLatch) > 0 )
+            Abc_ObjTransferFanout( pLatch, pLatchOut );
+        Abc_ObjAddFanin( pLatchOut, pLatch );
+        // add to the arrays
+        Vec_PtrPush( vCisNew, pLatchOut );
+        Vec_PtrPush( vCosNew, pLatchIn );
+        Vec_PtrPush( vBoxesNew, pLatch );
+    }
+    // free useless Cis/Cos
+    Vec_PtrForEachEntry( vCisOld, pObj, i )
+        if ( !Abc_ObjIsPi(pObj) && Abc_ObjFaninNum(pObj) == 0 && Abc_ObjFanoutNum(pObj) == 0 )
+            Abc_NtkDeleteObj(pObj);
+    Vec_PtrForEachEntry( vCosOld, pObj, i )
+        if ( !Abc_ObjIsPo(pObj) && Abc_ObjFaninNum(pObj) == 0 && Abc_ObjFanoutNum(pObj) == 0 )
+            Abc_NtkDeleteObj(pObj);
+    // set the new arrays
+    pNtk->vCis   = vCisNew;   Vec_PtrFree( vCisOld );
+    pNtk->vCos   = vCosNew;   Vec_PtrFree( vCosOld );
+    pNtk->vBoxes = vBoxesNew; Vec_PtrFree( vBoxesOld );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs retiming one way, forward or backward.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeOneWay( Abc_Ntk_t * pNtk, int fForward, int fVerbose )
+{
+    Abc_Ntk_t * pNtkNew;
+    Vec_Int_t * vValues;
+    Abc_Obj_t * pObj;
+    int i, fChanges, nTotalMoves = 0, nTotalMovesLimit = 10000;
+    if ( fForward )
+        Abc_NtkRetimeTranferToCopy( pNtk );
+    else
+    {
+        // save initial values of the latches
+        vValues = Abc_NtkRetimeCollectLatchValues( pNtk );
+        // start the network for initial value computation
+        pNtkNew = Abc_NtkRetimeBackwardInitialStart( pNtk );
+    }
+    // try to move latches forward whenever possible
+    do {
+        fChanges = 0;
+        Abc_NtkForEachObj( pNtk, pObj, i )
+        {
+            if ( !Abc_ObjIsNode(pObj) )
+                continue;
+            if ( Abc_NtkRetimeNodeIsEnabled( pObj, fForward ) )
+            {
+                Abc_NtkRetimeNode( pObj, fForward, 1 );
+                fChanges = 1;
+                nTotalMoves++;
+                if ( nTotalMoves >= nTotalMovesLimit )
+                {
+                    printf( "Stopped after %d latch moves.\n", nTotalMoves );
+                    break;
+                }
+            }
+        }
+    } while ( fChanges && nTotalMoves < nTotalMovesLimit );
+    // transfer the initial state back to the latches
+    if ( fForward )
+        Abc_NtkRetimeTranferFromCopy( pNtk );
+    else
+    {
+        Abc_NtkRetimeBackwardInitialFinish( pNtk, pNtkNew, vValues, fVerbose );
+        Abc_NtkDelete( pNtkNew );
+        Vec_IntFree( vValues );
+    }
+    return 0;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if retiming forward/backward is possible.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeNodeIsEnabled( Abc_Obj_t * pObj, int fForward )
+{
+    Abc_Obj_t * pNext;
+    int i;
+    assert( Abc_ObjIsNode(pObj) );
+    if ( fForward )
+    {
+        Abc_ObjForEachFanin( pObj, pNext, i )
+            if ( !Abc_ObjIsLatch(pNext) )
+                return 0;
+    }
+    else
+    {
+        Abc_ObjForEachFanout( pObj, pNext, i )
+            if ( !Abc_ObjIsLatch(pNext) )
+                return 0;
+    }
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Retimes the node backward or forward.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeNode( Abc_Obj_t * pObj, int fForward, int fInitial )
+{
+    Abc_Ntk_t * pNtkNew = NULL;
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pNext, * pLatch;
+    int i;
+    vNodes = Vec_PtrAlloc( 10 );
+    if ( fForward )
+    {
+        // compute the initial value
+        if ( fInitial )
+            pObj->pCopy = (void *)Abc_ObjSopSimulate( pObj );
+        // collect fanins
+        Abc_NodeCollectFanins( pObj, vNodes );
+        // make the node point to the fanins fanins
+        Vec_PtrForEachEntry( vNodes, pNext, i )
+        {
+            assert( Abc_ObjIsLatch(pNext) );
+            Abc_ObjPatchFanin( pObj, pNext, Abc_ObjFanin0(pNext) );
+            if ( Abc_ObjFanoutNum(pNext) == 0 )
+                Abc_NtkDeleteObj(pNext);            
+        }
+        // add a new latch on top
+        pNext = Abc_NtkCreateLatch(pObj->pNtk);
+        if ( Abc_ObjFanoutNum(pObj) > 0 )
+            Abc_ObjTransferFanout( pObj, pNext );
+        Abc_ObjAddFanin( pNext, pObj );
+        // set the initial value
+        if ( fInitial )
+            pNext->pCopy = pObj->pCopy;
+    }
+    else
+    {
+        // compute the initial value
+        if ( fInitial )
+        {
+            pNtkNew = Abc_ObjFanout0(pObj)->pCopy->pNtk;
+            Abc_NtkDupObj( pNtkNew, pObj, 0 );
+            Abc_ObjForEachFanout( pObj, pNext, i )
+            {
+                assert( Abc_ObjFaninNum(pNext->pCopy) == 0 );
+                Abc_ObjAddFanin( pNext->pCopy, pObj->pCopy );
+            }
+        }
+        // collect fanouts
+        Abc_NodeCollectFanouts( pObj, vNodes );
+        // make the fanouts fanouts point to the node
+        Vec_PtrForEachEntry( vNodes, pNext, i )
+        {
+            assert( Abc_ObjIsLatch(pNext) );
+            Abc_ObjTransferFanout( pNext, pObj );
+            Abc_NtkDeleteObj( pNext );  
+        }
+        // add new latches to the fanins
+        Abc_ObjForEachFanin( pObj, pNext, i )
+        {
+            pLatch = Abc_NtkCreateLatch(pObj->pNtk);
+            Abc_ObjPatchFanin( pObj, pNext, pLatch );
+            Abc_ObjAddFanin( pLatch, pNext );
+            // create buffer isomorphic to this latch
+            if ( fInitial )
+            {
+                pLatch->pCopy = Abc_NtkCreateNodeBuf( pNtkNew, NULL );
+                Abc_ObjAddFanin( pObj->pCopy, pLatch->pCopy );
+            }
+        }
+    }
+    Vec_PtrFree( vNodes );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the number of compatible fanout latches.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeCheckCompatibleLatchFanouts( Abc_Obj_t * pObj )
+{
+    Abc_Obj_t * pFanout;
+    int i, nLatches = 0, Init = -1;
+    Abc_ObjForEachFanout( pObj, pFanout, i )
+    {
+        if ( !Abc_ObjIsLatch(pFanout) )
+            continue;
+        if ( Init == -1 )
+        {
+            Init = (int)pObj->pData;
+            nLatches++;
+        }
+        else if ( Init == (int)pObj->pData )
+            nLatches++;
+    }
+    return nLatches;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Retimes the node backward or forward.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeShareLatches( Abc_Ntk_t * pNtk, int fInitial )
+{
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pFanin, * pLatchTop, * pLatchCur;
+    int i, k;
+    vNodes = Vec_PtrAlloc( 10 );
+    // consider latch fanins
+    Abc_NtkForEachObj( pNtk, pFanin, i )
+    {
+        if ( Abc_NtkRetimeCheckCompatibleLatchFanouts(pFanin) <= 1 )
+            continue;
+        // get the first latch
+        pLatchTop = NULL;
+        Abc_ObjForEachFanout( pFanin, pLatchTop, k )
+            if ( Abc_ObjIsLatch(pLatchTop) )
+                break;
+        assert( pLatchTop && Abc_ObjIsLatch(pLatchTop) );
+        // redirect compatible fanout latches to the first latch
+        Abc_NodeCollectFanouts( pFanin, vNodes );
+        Vec_PtrForEachEntry( vNodes, pLatchCur, k )
+        {
+            if ( !Abc_ObjIsLatch(pLatchCur) )
+                continue;
+            if ( pLatchCur == pLatchTop )
+                continue;
+            if ( pLatchCur->pData != pLatchTop->pData )
+                continue;
+            // connect the initial state
+            if ( fInitial )
+                Abc_ObjAddFanin( pLatchCur->pCopy, pLatchTop->pCopy );
+            // redirect the fanouts
+            Abc_ObjTransferFanout( pLatchCur, pLatchTop );
+            Abc_NtkDeleteObj(pLatchCur);
+        }
+    }
+    Vec_PtrFree( vNodes );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/retInit.c b/src/opt/ret/retInit.c
new file mode 100644
index 00000000..dcb71c60
--- /dev/null
+++ b/src/opt/ret/retInit.c
@@ -0,0 +1,349 @@
+/**CFile****************************************************************
+
+  FileName    [retInit.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    [Initial state computation for backward retiming.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retInit.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Abc_NtkRetimeVerifyModel( Abc_Ntk_t * pNtkCone, Vec_Int_t * vValues, int * pModel );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes initial values of the new latches.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Abc_NtkRetimeInitialValues( Abc_Ntk_t * pNtkCone, Vec_Int_t * vValues, int fVerbose )
+{
+    Vec_Int_t * vSolution;
+    Abc_Ntk_t * pNtkMiter, * pNtkLogic;
+    int RetValue, clk;
+    if ( pNtkCone == NULL )
+        return Vec_IntDup( vValues );
+    // convert the target network to AIG
+    pNtkLogic = Abc_NtkDup( pNtkCone );
+    Abc_NtkToAig( pNtkLogic );
+    // get the miter
+    pNtkMiter = Abc_NtkCreateTarget( pNtkLogic, pNtkLogic->vCos, vValues );
+    if ( fVerbose )
+        printf( "The miter for initial state computation has %d AIG nodes. ", Abc_NtkNodeNum(pNtkMiter) );
+    // solve the miter
+    clk = clock();
+    RetValue = Abc_NtkMiterSat( pNtkMiter, (sint64)500000, (sint64)50000000, 0, NULL, NULL );
+    if ( fVerbose ) 
+        { PRT( "SAT solving time", clock() - clk ); }
+    // analyze the result
+    if ( RetValue == 1 )
+        printf( "Abc_NtkRetimeInitialValues(): The problem is unsatisfiable. DC latch values are used.\n" );
+    else if ( RetValue == -1 )
+        printf( "Abc_NtkRetimeInitialValues(): The SAT problem timed out. DC latch values are used.\n" );
+    else if ( !Abc_NtkRetimeVerifyModel( pNtkCone, vValues, pNtkMiter->pModel ) )
+        printf( "Abc_NtkRetimeInitialValues(): The computed counter-example is incorrect.\n" );
+    // set the values of the latches
+    vSolution = RetValue? NULL : Vec_IntAllocArray( pNtkMiter->pModel, Abc_NtkPiNum(pNtkLogic) );
+    pNtkMiter->pModel = NULL;
+    Abc_NtkDelete( pNtkMiter );
+    Abc_NtkDelete( pNtkLogic );
+    return vSolution;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the results of simulating one node.]
+
+  Description [Assumes that fanins have pCopy set to the input values.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_ObjSopSimulate( Abc_Obj_t * pObj )
+{
+    char * pCube, * pSop = pObj->pData;
+    int nVars, Value, v, ResOr, ResAnd, ResVar;
+    assert( pSop && !Abc_SopIsExorType(pSop) );
+    // simulate the SOP of the node
+    ResOr = 0;
+    nVars = Abc_SopGetVarNum(pSop);
+    Abc_SopForEachCube( pSop, nVars, pCube )
+    {
+        ResAnd = 1;
+        Abc_CubeForEachVar( pCube, Value, v )
+        {
+            if ( Value == '0' )
+                ResVar = 1 ^ ((int)Abc_ObjFanin(pObj, v)->pCopy);
+            else if ( Value == '1' )
+                ResVar = (int)Abc_ObjFanin(pObj, v)->pCopy;
+            else
+                continue;
+            ResAnd &= ResVar;
+        }
+        ResOr |= ResAnd;
+    }
+    // complement the result if necessary
+    if ( !Abc_SopGetPhase(pSop) )
+        ResOr ^= 1;
+    return ResOr;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies the counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeVerifyModel( Abc_Ntk_t * pNtkCone, Vec_Int_t * vValues, int * pModel )
+{
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pObj;
+    int i, Counter = 0;
+    assert( Abc_NtkIsSopLogic(pNtkCone) );
+    // set the PIs
+    Abc_NtkForEachPi( pNtkCone, pObj, i )
+        pObj->pCopy = (void *)pModel[i];
+    // simulate the internal nodes
+    vNodes = Abc_NtkDfs( pNtkCone, 0 );
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        pObj->pCopy = (void *)Abc_ObjSopSimulate( pObj );
+    Vec_PtrFree( vNodes );
+    // compare the outputs
+    Abc_NtkForEachPo( pNtkCone, pObj, i )
+        pObj->pCopy = Abc_ObjFanin0(pObj)->pCopy;
+    Abc_NtkForEachPo( pNtkCone, pObj, i )
+        Counter += (Vec_IntEntry(vValues, i) != (int)pObj->pCopy);
+    if ( Counter > 0 )
+        printf( "%d outputs (out of %d) have a value mismatch.\n", Counter, Abc_NtkPoNum(pNtkCone) );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfer latch initial values to pCopy.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeTranferToCopy( Abc_Ntk_t * pNtk )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsLatch(pObj) )
+            pObj->pCopy = (void *)Abc_LatchIsInit1(pObj);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfer latch initial values from pCopy.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeTranferFromCopy( Abc_Ntk_t * pNtk )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsLatch(pObj) )
+            pObj->pData = (void *)(pObj->pCopy? ABC_INIT_ONE : ABC_INIT_ZERO);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfer latch initial values to pCopy.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Abc_NtkRetimeCollectLatchValues( Abc_Ntk_t * pNtk )
+{
+    Vec_Int_t * vValues;
+    Abc_Obj_t * pObj;
+    int i;
+    vValues = Vec_IntAlloc( Abc_NtkLatchNum(pNtk) );
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsLatch(pObj) )
+            Vec_IntPush( vValues, Abc_LatchIsInit1(pObj) );
+    return vValues;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfer latch initial values from pCopy.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeInsertLatchValues( Abc_Ntk_t * pNtk, Vec_Int_t * vValues )
+{
+    Abc_Obj_t * pObj;
+    int i, Counter = 0;
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsLatch(pObj) )
+            pObj->pCopy = (void *)Counter++;
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsLatch(pObj) )
+            pObj->pData = (void *)(vValues? (Vec_IntEntry(vValues,(int)pObj->pCopy)? ABC_INIT_ONE : ABC_INIT_ZERO) : ABC_INIT_DC);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfer latch initial values to pCopy.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Abc_NtkRetimeBackwardInitialStart( Abc_Ntk_t * pNtk )
+{
+    Abc_Ntk_t * pNtkNew;
+    Abc_Obj_t * pObj;
+    int i;
+    // create the network used for the initial state computation
+    pNtkNew = Abc_NtkAlloc( ABC_NTK_LOGIC, ABC_FUNC_SOP, 1 );
+    // create POs corresponding to the initial values
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsLatch(pObj) )
+            pObj->pCopy = Abc_NtkCreatePo(pNtkNew);
+    return pNtkNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfer latch initial values to pCopy.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkRetimeBackwardInitialFinish( Abc_Ntk_t * pNtk, Abc_Ntk_t * pNtkNew, Vec_Int_t * vValuesOld, int fVerbose )
+{
+    Vec_Int_t * vValuesNew;
+    Abc_Obj_t * pObj;
+    int i;
+    // create PIs corresponding to the initial values
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjIsLatch(pObj) )
+            Abc_ObjAddFanin( pObj->pCopy, Abc_NtkCreatePi(pNtkNew) );
+    // assign dummy node names
+    Abc_NtkAddDummyPiNames( pNtkNew );
+    Abc_NtkAddDummyPoNames( pNtkNew );
+    // check the network
+    if ( !Abc_NtkCheck( pNtkNew ) )
+        fprintf( stdout, "Abc_NtkRetimeBackwardInitialFinish(): Network check has failed.\n" );
+    // derive new initial values
+    vValuesNew = Abc_NtkRetimeInitialValues( pNtkNew, vValuesOld, fVerbose );
+    // insert new initial values
+    Abc_NtkRetimeInsertLatchValues( pNtk, vValuesNew );
+    if ( vValuesNew ) Vec_IntFree( vValuesNew );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Cycles the circuit to create a new initial state.]
+
+  Description [Simulates the circuit with random input for the given 
+  number of timeframes to get a better initial state.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkCycleInitStateSop( Abc_Ntk_t * pNtk, int nFrames, int fVerbose )
+{
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pObj;
+    int i, f;
+    assert( Abc_NtkIsSopLogic(pNtk) );
+    srand( 0x12341234 );
+    // initialize the values
+    Abc_NtkForEachPi( pNtk, pObj, i )
+        pObj->pCopy = (void *)(rand() & 1);
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        pObj->pCopy = (void *)Abc_LatchIsInit1(pObj);
+    // simulate for the given number of timeframes
+    vNodes = Abc_NtkDfs( pNtk, 0 );
+    for ( f = 0; f < nFrames; f++ )
+    {
+        // simulate internal nodes
+        Vec_PtrForEachEntry( vNodes, pObj, i )
+            pObj->pCopy = (void *)Abc_ObjSopSimulate( pObj );
+        // bring the results to the COs
+        Abc_NtkForEachCo( pNtk, pObj, i )
+            pObj->pCopy = Abc_ObjFanin0(pObj)->pCopy;
+        // assign PI values
+        Abc_NtkForEachPi( pNtk, pObj, i )
+            pObj->pCopy = (void *)(rand() & 1);
+        // transfer the latch values
+        Abc_NtkForEachLatch( pNtk, pObj, i )
+            Abc_ObjFanout0(pObj)->pCopy = Abc_ObjFanin0(pObj)->pCopy;
+    }
+    Vec_PtrFree( vNodes );
+    // set the final values
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        pObj->pData = (void *)(Abc_ObjFanout0(pObj)->pCopy ? ABC_INIT_ONE : ABC_INIT_ZERO);
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/retInt.h b/src/opt/ret/retInt.h
new file mode 100644
index 00000000..51428bce
--- /dev/null
+++ b/src/opt/ret/retInt.h
@@ -0,0 +1,80 @@
+/**CFile****************************************************************
+
+  FileName    [retInt.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    [Internal declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retInt.h,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __RET_INT_H__
+#define __RET_INT_H__
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "abc.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    STRUCTURE DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                       MACRO DEFINITIONS                          ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== retArea.c ========================================================*/
+extern int         Abc_NtkRetimeMinArea( Abc_Ntk_t * pNtk, int fForwardOnly, int fBackwardOnly, int fVerbose );
+/*=== retCore.c ========================================================*/
+extern int         Abc_NtkRetime( Abc_Ntk_t * pNtk, int Mode, int fForwardOnly, int fBackwardOnly, int fOneStep, int fVerbose );
+/*=== retDelay.c ========================================================*/
+extern int         Abc_NtkRetimeMinDelay( Abc_Ntk_t * pNtk, Abc_Ntk_t * pNtkCopy, int nIterLimit, int fForward, int fVerbose );
+/*=== retDirect.c ========================================================*/
+extern int         Abc_NtkRetimeIncremental( Abc_Ntk_t * pNtk, int fForward, int fMinDelay, int fOneStep, int fVerbose );
+extern void        Abc_NtkRetimeShareLatches( Abc_Ntk_t * pNtk, int fInitial );
+extern int         Abc_NtkRetimeNodeIsEnabled( Abc_Obj_t * pObj, int fForward );
+extern void        Abc_NtkRetimeNode( Abc_Obj_t * pObj, int fForward, int fInitial );
+extern st_table *  Abc_NtkRetimePrepareLatches( Abc_Ntk_t * pNtk );
+extern int         Abc_NtkRetimeFinalizeLatches( Abc_Ntk_t * pNtk, st_table * tLatches, int nIdMaxStart );
+/*=== retFlow.c ========================================================*/
+extern void        Abc_NtkMaxFlowTest( Abc_Ntk_t * pNtk );
+extern Vec_Ptr_t * Abc_NtkMaxFlow( Abc_Ntk_t * pNtk, int fForward, int fVerbose );
+/*=== retInit.c ========================================================*/
+extern Vec_Int_t * Abc_NtkRetimeInitialValues( Abc_Ntk_t * pNtkSat, Vec_Int_t * vValues, int fVerbose );
+extern int         Abc_ObjSopSimulate( Abc_Obj_t * pObj );
+extern void        Abc_NtkRetimeTranferToCopy( Abc_Ntk_t * pNtk );
+extern void        Abc_NtkRetimeTranferFromCopy( Abc_Ntk_t * pNtk );
+extern Vec_Int_t * Abc_NtkRetimeCollectLatchValues( Abc_Ntk_t * pNtk );
+extern void        Abc_NtkRetimeInsertLatchValues( Abc_Ntk_t * pNtk, Vec_Int_t * vValues );
+extern Abc_Ntk_t * Abc_NtkRetimeBackwardInitialStart( Abc_Ntk_t * pNtk );
+extern void        Abc_NtkRetimeBackwardInitialFinish( Abc_Ntk_t * pNtk, Abc_Ntk_t * pNtkNew, Vec_Int_t * vValuesOld, int fVerbose );
+/*=== retLvalue.c ========================================================*/
+extern int         Abc_NtkRetimeLValue( Abc_Ntk_t * pNtk, int nIterLimit, int fVerbose );
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/retLvalue.c b/src/opt/ret/retLvalue.c
new file mode 100644
index 00000000..b4d9e946
--- /dev/null
+++ b/src/opt/ret/retLvalue.c
@@ -0,0 +1,395 @@
+/**CFile****************************************************************
+
+  FileName    [retLvalue.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    [Implementation of Pan's retiming algorithm.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: retLvalue.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// node status after updating its arrival time
+enum { ABC_RET_UPDATE_FAIL, ABC_RET_UPDATE_NO, ABC_RET_UPDATE_YES };
+
+// the internal procedures
+static Vec_Int_t * Abc_NtkRetimeGetLags( Abc_Ntk_t * pNtk, int nIterLimit, int fVerbose );
+static int         Abc_NtkRetimeSearch_rec( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes, Vec_Ptr_t * vLatches, int FiMin, int FiMax, int nMaxIters, int fVerbose );
+static int         Abc_NtkRetimeForPeriod( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes, Vec_Ptr_t * vLatches, int Fi, int nMaxIters, int fVerbose );
+static int         Abc_NtkRetimeUpdateLValue( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes, Vec_Ptr_t * vLatches, int Fi );
+static int         Abc_NtkRetimePosOverLimit( Abc_Ntk_t * pNtk, int Fi );
+static Vec_Ptr_t * Abc_ManCollectLatches( Abc_Ntk_t * pNtk );
+static int         Abc_NtkRetimeUsingLags( Abc_Ntk_t * pNtk, Vec_Int_t * vLags, int fVerbose );
+
+static inline int  Abc_NodeComputeLag( int LValue, int Fi )          { return (LValue + (1<<16)*Fi)/Fi - (1<<16) - (int)(LValue % Fi == 0);     }
+static inline int  Abc_NodeGetLValue( Abc_Obj_t * pNode )            { return (int)pNode->pCopy;        }
+static inline void Abc_NodeSetLValue( Abc_Obj_t * pNode, int Value ) { pNode->pCopy = (void *)Value;    }
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Implements Pan's retiming algorithm.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeLValue( Abc_Ntk_t * pNtk, int nIterLimit, int fVerbose )
+{
+    Vec_Int_t * vLags;
+    int nLatches = Abc_NtkLatchNum(pNtk);
+    assert( Abc_NtkIsLogic( pNtk ) );
+    // get the lags
+    vLags = Abc_NtkRetimeGetLags( pNtk, nIterLimit, fVerbose );
+    // compute the retiming
+//    Abc_NtkRetimeUsingLags( pNtk, vLags, fVerbose );
+    Vec_IntFree( vLags );
+    // fix the COs
+//    Abc_NtkLogicMakeSimpleCos( pNtk, 0 );
+    // check for correctness
+    if ( !Abc_NtkCheck( pNtk ) )
+        fprintf( stdout, "Abc_NtkRetimeLValue(): Network check has failed.\n" );
+    // return the number of latches saved
+    return nLatches - Abc_NtkLatchNum(pNtk);
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes the retiming lags.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Abc_NtkRetimeGetLags( Abc_Ntk_t * pNtk, int nIterLimit, int fVerbose )
+{
+    Vec_Int_t * vLags;
+    Vec_Ptr_t * vNodes, * vLatches;
+    Abc_Obj_t * pNode;
+    int i, FiMax, FiBest, RetValue, clk, clkIter;
+    char NodeLag;
+
+    // get the upper bound on the clock period
+    FiMax = Abc_NtkLevel(pNtk);
+
+    // make sure this clock period is feasible
+    vNodes = Abc_NtkDfs( pNtk, 0 );
+    vLatches = Abc_ManCollectLatches( pNtk );
+    if ( !Abc_NtkRetimeForPeriod( pNtk, vNodes, vLatches, FiMax, nIterLimit, fVerbose ) )
+    {
+        Vec_PtrFree( vNodes );
+        printf( "Abc_NtkRetimeGetLags() error: The upper bound on the clock period cannot be computed.\n" );
+        return Vec_IntStart( Abc_NtkObjNumMax(pNtk) + 1 );
+    }
+ 
+    // search for the optimal clock period between 0 and nLevelMax
+clk = clock();
+    FiBest = Abc_NtkRetimeSearch_rec( pNtk, vNodes, vLatches, 0, FiMax, nIterLimit, fVerbose );
+clkIter = clock() - clk;
+
+    // recompute the best l-values
+    RetValue = Abc_NtkRetimeForPeriod( pNtk, vNodes, vLatches, FiBest, nIterLimit, fVerbose );
+    assert( RetValue );
+
+    // fix the problem with non-converged delays
+    Abc_NtkForEachNode( pNtk, pNode, i )
+        if ( Abc_NodeGetLValue(pNode) < -ABC_INFINITY/2 )
+            Abc_NodeSetLValue( pNode, 0 );
+
+    // write the retiming lags
+    vLags = Vec_IntStart( Abc_NtkObjNumMax(pNtk) + 1 );
+    Abc_NtkForEachNode( pNtk, pNode, i )
+    {
+        NodeLag = Abc_NodeComputeLag( Abc_NodeGetLValue(pNode), FiBest );
+        Vec_IntWriteEntry( vLags, pNode->Id, NodeLag );
+    }
+/*
+    Abc_NtkForEachPo( pNtk, pNode, i )
+        printf( "%d ", Abc_NodeGetLValue(Abc_ObjFanin0(pNode)) );
+    printf( "\n" );
+    Abc_NtkForEachLatch( pNtk, pNode, i )
+        printf( "%d/%d ", Abc_NodeGetLValue(Abc_ObjFanout0(pNode)), Abc_NodeGetLValue(Abc_ObjFanout0(pNode)) + FiBest );
+    printf( "\n" );
+*/
+
+    // print the result
+//    if ( fVerbose )
+    printf( "The best clock period is %3d. (Currently, network is not modified.)\n", FiBest );
+/*
+    {
+        FILE * pTable;
+        pTable = fopen( "iscas/seqmap__stats2.txt", "a+" );
+        fprintf( pTable, "%d ", FiBest );
+        fprintf( pTable, "\n" );
+        fclose( pTable );
+    }
+*/
+    Vec_PtrFree( vNodes );
+    Vec_PtrFree( vLatches );
+    return vLags;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs binary search for the optimal clock period.]
+
+  Description [Assumes that FiMin is infeasible while FiMax is feasible.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeSearch_rec( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes, Vec_Ptr_t * vLatches, int FiMin, int FiMax, int nMaxIters, int fVerbose )
+{
+    int Median;
+    assert( FiMin < FiMax );
+    if ( FiMin + 1 == FiMax )
+        return FiMax;
+    Median = FiMin + (FiMax - FiMin)/2;
+    if ( Abc_NtkRetimeForPeriod( pNtk, vNodes, vLatches, Median, nMaxIters, fVerbose ) )
+        return Abc_NtkRetimeSearch_rec( pNtk, vNodes, vLatches, FiMin, Median, nMaxIters, fVerbose ); // Median is feasible
+    else 
+        return Abc_NtkRetimeSearch_rec( pNtk, vNodes, vLatches, Median, FiMax, nMaxIters, fVerbose ); // Median is infeasible
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if retiming with this clock period is feasible.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeForPeriod( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes, Vec_Ptr_t * vLatches, int Fi, int nMaxIters, int fVerbose )
+{
+    Abc_Obj_t * pObj;
+    int c, i, fConverged;
+    // set l-values of all nodes to be minus infinity, except PIs and constants
+    Abc_NtkForEachObj( pNtk, pObj, i )
+        if ( Abc_ObjFaninNum(pObj) == 0 )
+            Abc_NodeSetLValue( pObj, 0 );
+        else
+            Abc_NodeSetLValue( pObj, -ABC_INFINITY );
+    // update all values iteratively
+    fConverged = 0;
+    for ( c = 1; c <= nMaxIters; c++ )
+    {
+        if ( !Abc_NtkRetimeUpdateLValue( pNtk, vNodes, vLatches, Fi ) )
+        {
+            fConverged = 1;
+            break;
+        }
+        if ( Abc_NtkRetimePosOverLimit(pNtk, Fi) )
+            break;
+    }
+    // report the results
+    if ( fVerbose )
+    {
+        if ( !fConverged )
+            printf( "Period = %3d.  Iterations = %3d.    Infeasible %s\n", Fi, c, (c > nMaxIters)? "(timeout)" : "" );
+        else
+            printf( "Period = %3d.  Iterations = %3d.      Feasible\n",    Fi, c );
+    }
+/*
+    // check if any AND gates have infinite delay
+    Counter = 0;
+    Abc_NtkForEachNode( pNtk, pObj, i )
+        Counter += (Abc_NodeGetLValue(pObj) < -ABC_INFINITY/2);
+    if ( Counter > 0 )
+        printf( "Warning: %d internal nodes have wrong l-values!\n", Counter );
+*/
+    return fConverged;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs one iteration of l-value computation for the nodes.]
+
+  Description [Experimentally it was found that checking POs changes
+  is not enough to detect the convergence of l-values in the network.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeUpdateLValue( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes, Vec_Ptr_t * vLatches, int Fi )
+{
+    Abc_Obj_t * pObj, * pFanin;
+    int i, k, lValueNew, fChange;
+    // go through the nodes and detect change
+    fChange = 0;
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+    {
+        assert( Abc_ObjIsNode(pObj) );
+        lValueNew = -ABC_INFINITY;
+        Abc_ObjForEachFanin( pObj, pFanin, k )
+        {
+            if ( lValueNew < Abc_NodeGetLValue(pFanin) )
+                lValueNew = Abc_NodeGetLValue(pFanin);
+        }
+        lValueNew++;
+        if ( Abc_NodeGetLValue(pObj) < lValueNew )
+        {
+            Abc_NodeSetLValue( pObj, lValueNew );
+            fChange = 1;
+        }
+    }
+    // propagate values through the latches
+    Vec_PtrForEachEntry( vLatches, pObj, i )
+        Abc_NodeSetLValue( Abc_ObjFanout0(pObj), Abc_NodeGetLValue(Abc_ObjFanin0(Abc_ObjFanin0(pObj))) - Fi );
+    return fChange;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Detects the case when l-values exceeded the limit.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimePosOverLimit( Abc_Ntk_t * pNtk, int Fi )
+{
+    Abc_Obj_t * pObj;
+    int i;
+    Abc_NtkForEachPo( pNtk, pObj, i )
+        if ( Abc_NodeGetLValue(Abc_ObjFanin0(pObj)) > Fi )
+            return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects latches in the topological order.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+ 
+***********************************************************************/
+void Abc_ManCollectLatches_rec( Abc_Obj_t * pObj, Vec_Ptr_t * vLatches )
+{
+    Abc_Obj_t * pDriver;
+    if ( !Abc_ObjIsLatch(pObj) )
+        return;
+    // skip already collected latches
+    if ( Abc_NodeIsTravIdCurrent(pObj)  )
+        return;
+    Abc_NodeSetTravIdCurrent(pObj);
+    // get the driver node feeding into the latch
+    pDriver = Abc_ObjFanin0(Abc_ObjFanin0(pObj));
+    // call recursively if the driver looks like a latch output
+    if ( Abc_ObjIsBo(pDriver) )
+        Abc_ManCollectLatches_rec( Abc_ObjFanin0(pDriver), vLatches );
+    // collect the latch
+    Vec_PtrPush( vLatches, pObj );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects latches in the topological order.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Abc_ManCollectLatches( Abc_Ntk_t * pNtk )
+{
+    Vec_Ptr_t * vLatches;
+    Abc_Obj_t * pObj;
+    int i;
+    vLatches = Vec_PtrAlloc( Abc_NtkLatchNum(pNtk) );
+    Abc_NtkIncrementTravId( pNtk );
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+        Abc_ManCollectLatches_rec( pObj, vLatches );
+    assert( Vec_PtrSize(vLatches) == Abc_NtkLatchNum(pNtk) );
+    return vLatches;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements the retiming given as the array of retiming lags.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkRetimeUsingLags( Abc_Ntk_t * pNtk, Vec_Int_t * vLags, int fVerbose )
+{
+    Abc_Obj_t * pObj;
+    int fChanges, fForward, nTotalMoves, Lag, Counter, i;
+    // iterate over the nodes
+    nTotalMoves = 0;
+    do {
+        fChanges = 0;
+        Abc_NtkForEachNode( pNtk, pObj, i )
+        {
+            Lag = Vec_IntEntry( vLags, pObj->Id );
+            if ( !Lag )
+                continue;
+            fForward = (Lag < 0);
+            if ( Abc_NtkRetimeNodeIsEnabled( pObj, fForward ) )
+            {
+                Abc_NtkRetimeNode( pObj, fForward, 0 );
+                fChanges = 1;
+                nTotalMoves++;
+                Vec_IntAddToEntry( vLags, pObj->Id, fForward? 1 : -1 );
+            }
+        }
+    } while ( fChanges );
+    if ( fVerbose )
+        printf( "Total latch moves = %d.\n", nTotalMoves );
+    // check if there are remaining lags
+    Counter = 0;
+    Abc_NtkForEachNode( pNtk, pObj, i )
+        Counter += (Vec_IntEntry( vLags, pObj->Id ) != 0);
+    if ( Counter )
+        printf( "Warning! The number of nodes with unrealized lag = %d.\n", Counter );
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/ret/ret_.c b/src/opt/ret/ret_.c
new file mode 100644
index 00000000..89625e17
--- /dev/null
+++ b/src/opt/ret/ret_.c
@@ -0,0 +1,48 @@
+/**CFile****************************************************************
+
+  FileName    [ret_.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Retiming package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - Oct 31, 2006.]
+
+  Revision    [$Id: ret_.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "retInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/module.make b/src/opt/rwr/module.make
new file mode 100644
index 00000000..077a3c01
--- /dev/null
+++ b/src/opt/rwr/module.make
@@ -0,0 +1,7 @@
+SRC +=  src/opt/rwr/rwrDec.c \
+    src/opt/rwr/rwrEva.c \
+    src/opt/rwr/rwrExp.c \
+    src/opt/rwr/rwrLib.c \
+    src/opt/rwr/rwrMan.c \
+    src/opt/rwr/rwrPrint.c \
+    src/opt/rwr/rwrUtil.c
diff --git a/src/opt/rwr/rwr.h b/src/opt/rwr/rwr.h
new file mode 100644
index 00000000..f24f9535
--- /dev/null
+++ b/src/opt/rwr/rwr.h
@@ -0,0 +1,169 @@
+/**CFile****************************************************************
+
+  FileName    [rwr.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwr.h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+ 
+#ifndef __RWR_H__
+#define __RWR_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+#include "abc.h"
+#include "cut.h"
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+ 
+#define RWR_LIMIT  1048576/4  // ((1 << 20) 
+
+typedef struct Rwr_Man_t_   Rwr_Man_t;
+typedef struct Rwr_Node_t_  Rwr_Node_t;
+
+struct Rwr_Man_t_
+{
+    // internal lookups
+    int                nFuncs;           // number of four var functions
+    unsigned short *   puCanons;         // canonical forms
+    char *             pPhases;          // canonical phases
+    char *             pPerms;           // canonical permutations
+    unsigned char *    pMap;             // mapping of functions into class numbers
+    unsigned short *   pMapInv;          // mapping of classes into functions
+    char *             pPractical;       // practical NPN classes
+    char **            pPerms4;          // four-var permutations
+    // node space
+    Vec_Ptr_t *        vForest;          // all the nodes
+    Rwr_Node_t **      pTable;           // the hash table of nodes by their canonical form
+    Vec_Vec_t *        vClasses;         // the nodes of the equivalence classes
+    Extra_MmFixed_t *  pMmNode;          // memory for nodes and cuts
+    // statistical variables
+    int                nTravIds;         // the counter of traversal IDs
+    int                nConsidered;      // the number of nodes considered
+    int                nAdded;           // the number of nodes added to lists
+    int                nClasses;         // the number of NN classes
+    // the result of resynthesis
+    int                fCompl;           // indicates if the output of FF should be complemented
+    void *             pGraph;           // the decomposition tree (temporary)
+    Vec_Ptr_t *        vFanins;          // the fanins array (temporary)
+    Vec_Ptr_t *        vFaninsCur;       // the fanins array (temporary)
+    Vec_Int_t *        vLevNums;         // the array of levels (temporary)
+    Vec_Ptr_t *        vNodesTemp;       // the nodes in MFFC (temporary)
+    // node statistics
+    int                nNodesConsidered;
+    int                nNodesRewritten;
+    int                nNodesGained;
+    int                nNodesBeg;
+    int                nNodesEnd;
+    int                nScores[222];
+    int                nCutsGood;
+    int                nCutsBad;
+    int                nSubgraphs;
+    // runtime statistics
+    int                timeStart;
+    int                timeCut;
+    int                timeRes;
+    int                timeEval;
+    int                timeMffc;
+    int                timeUpdate;
+    int                timeTotal;
+};
+
+struct Rwr_Node_t_ // 24 bytes
+{
+    int                Id;               // ID 
+    int                TravId;           // traversal ID
+    short              nScore;
+    short              nGain;
+    short              nAdded;
+    unsigned           uTruth : 16;      // truth table
+    unsigned           Volume :  8;      // volume
+    unsigned           Level  :  6;      // level
+    unsigned           fUsed  :  1;      // mark
+    unsigned           fExor  :  1;      // mark
+    Rwr_Node_t *       p0;               // first child
+    Rwr_Node_t *       p1;               // second child
+    Rwr_Node_t *       pNext;            // next in the table
+};
+
+// manipulation of complemented attributes
+static inline bool         Rwr_IsComplement( Rwr_Node_t * p )    { return (bool)(((unsigned long)p) & 01);           }
+static inline Rwr_Node_t * Rwr_Regular( Rwr_Node_t * p )         { return (Rwr_Node_t *)((unsigned long)(p) & ~01);  }
+static inline Rwr_Node_t * Rwr_Not( Rwr_Node_t * p )             { return (Rwr_Node_t *)((unsigned long)(p) ^  01);  }
+static inline Rwr_Node_t * Rwr_NotCond( Rwr_Node_t * p, int c )  { return (Rwr_Node_t *)((unsigned long)(p) ^ (c));  }
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== rwrDec.c ========================================================*/
+extern void              Rwr_ManPreprocess( Rwr_Man_t * p );
+/*=== rwrEva.c ========================================================*/
+extern int               Rwr_NodeRewrite( Rwr_Man_t * p, Cut_Man_t * pManCut, Abc_Obj_t * pNode, int fUpdateLevel, int fUseZeros, int fPlaceEnable );
+extern void              Rwr_ScoresClean( Rwr_Man_t * p );
+extern void              Rwr_ScoresReport( Rwr_Man_t * p );
+/*=== rwrLib.c ========================================================*/
+extern void              Rwr_ManPrecompute( Rwr_Man_t * p );
+extern Rwr_Node_t *      Rwr_ManAddVar( Rwr_Man_t * p, unsigned uTruth, int fPrecompute );
+extern Rwr_Node_t *      Rwr_ManAddNode( Rwr_Man_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume );
+extern int               Rwr_ManNodeVolume( Rwr_Man_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1 );
+extern void              Rwr_ManIncTravId( Rwr_Man_t * p );
+/*=== rwrMan.c ========================================================*/
+extern Rwr_Man_t *       Rwr_ManStart( bool fPrecompute );
+extern void              Rwr_ManStop( Rwr_Man_t * p );
+extern void              Rwr_ManPrintStats( Rwr_Man_t * p );
+extern void              Rwr_ManPrintStatsFile( Rwr_Man_t * p );
+extern void *            Rwr_ManReadDecs( Rwr_Man_t * p );
+extern Vec_Ptr_t *       Rwr_ManReadLeaves( Rwr_Man_t * p );
+extern int               Rwr_ManReadCompl( Rwr_Man_t * p );
+extern void              Rwr_ManAddTimeCuts( Rwr_Man_t * p, int Time );
+extern void              Rwr_ManAddTimeUpdate( Rwr_Man_t * p, int Time );
+extern void              Rwr_ManAddTimeTotal( Rwr_Man_t * p, int Time );
+/*=== rwrPrint.c ========================================================*/
+extern void              Rwr_ManPrint( Rwr_Man_t * p );
+/*=== rwrUtil.c ========================================================*/
+extern void              Rwr_ManWriteToArray( Rwr_Man_t * p );
+extern void              Rwr_ManLoadFromArray( Rwr_Man_t * p, int fVerbose );
+extern void              Rwr_ManWriteToFile( Rwr_Man_t * p, char * pFileName );
+extern void              Rwr_ManLoadFromFile( Rwr_Man_t * p, char * pFileName );
+extern void              Rwr_ListAddToTail( Rwr_Node_t ** ppList, Rwr_Node_t * pNode );
+extern char *            Rwr_ManGetPractical( Rwr_Man_t * p );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/rwr/rwrDec.c b/src/opt/rwr/rwrDec.c
new file mode 100644
index 00000000..ef7af34f
--- /dev/null
+++ b/src/opt/rwr/rwrDec.c
@@ -0,0 +1,150 @@
+/**CFile****************************************************************
+
+  FileName    [rwrDec.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Evaluation and decomposition procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrDec.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+#include "dec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Dec_Graph_t * Rwr_NodePreprocess( Rwr_Man_t * p, Rwr_Node_t * pNode );
+static Dec_Edge_t    Rwr_TravCollect_rec( Rwr_Man_t * p, Rwr_Node_t * pNode, Dec_Graph_t * pGraph );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Preprocesses computed library of subgraphs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManPreprocess( Rwr_Man_t * p )
+{
+    Dec_Graph_t * pGraph;
+    Rwr_Node_t * pNode;
+    int i, k;
+    // put the nodes into the structure
+    p->pMapInv  = ALLOC( unsigned short, 222 );
+    memset( p->pMapInv, 0, sizeof(unsigned short) * 222 );
+    p->vClasses = Vec_VecStart( 222 );
+    for ( i = 0; i < p->nFuncs; i++ )
+    {
+        if ( p->pTable[i] == NULL )
+            continue;
+        // consider all implementations of this function
+        for ( pNode = p->pTable[i]; pNode; pNode = pNode->pNext )
+        {
+            assert( pNode->uTruth == p->pTable[i]->uTruth );
+            assert( p->pMap[pNode->uTruth] >= 0 && p->pMap[pNode->uTruth] < 222 );
+            Vec_VecPush( p->vClasses, p->pMap[pNode->uTruth], pNode );
+            p->pMapInv[ p->pMap[pNode->uTruth] ] = p->puCanons[pNode->uTruth];
+        }
+    }
+    // compute decomposition forms for each node and verify them
+    Vec_VecForEachEntry( p->vClasses, pNode, i, k )
+    {
+        pGraph = Rwr_NodePreprocess( p, pNode );
+        pNode->pNext = (Rwr_Node_t *)pGraph;
+        assert( pNode->uTruth == (Dec_GraphDeriveTruth(pGraph) & 0xFFFF) );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Preprocesses subgraphs rooted at this node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Graph_t * Rwr_NodePreprocess( Rwr_Man_t * p, Rwr_Node_t * pNode )
+{
+    Dec_Graph_t * pGraph;
+    Dec_Edge_t eRoot;
+    assert( !Rwr_IsComplement(pNode) );
+    // consider constant
+    if ( pNode->uTruth == 0 )
+        return Dec_GraphCreateConst0();
+    // consider the case of elementary var
+    if ( pNode->uTruth == 0x00FF )
+        return Dec_GraphCreateLeaf( 3, 4, 1 );
+    // start the subgraphs
+    pGraph = Dec_GraphCreate( 4 );
+    // collect the nodes
+    Rwr_ManIncTravId( p );
+    eRoot = Rwr_TravCollect_rec( p, pNode, pGraph );
+    Dec_GraphSetRoot( pGraph, eRoot );
+    return pGraph;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Edge_t Rwr_TravCollect_rec( Rwr_Man_t * p, Rwr_Node_t * pNode, Dec_Graph_t * pGraph )
+{
+    Dec_Edge_t eNode0, eNode1, eNode;
+    // elementary variable
+    if ( pNode->fUsed )
+        return Dec_EdgeCreate( pNode->Id - 1, 0 );
+    // previously visited node
+    if ( pNode->TravId == p->nTravIds )
+        return Dec_IntToEdge( pNode->Volume );
+    pNode->TravId = p->nTravIds;
+    // solve for children
+    eNode0 = Rwr_TravCollect_rec( p, Rwr_Regular(pNode->p0), pGraph );
+    if ( Rwr_IsComplement(pNode->p0) )    
+        eNode0.fCompl = !eNode0.fCompl;
+    eNode1 = Rwr_TravCollect_rec( p, Rwr_Regular(pNode->p1), pGraph );
+    if ( Rwr_IsComplement(pNode->p1) )    
+        eNode1.fCompl = !eNode1.fCompl;
+    // create the decomposition node(s)
+    if ( pNode->fExor )
+        eNode = Dec_GraphAddNodeXor( pGraph, eNode0, eNode1, 0 );
+    else
+        eNode = Dec_GraphAddNodeAnd( pGraph, eNode0, eNode1 );
+    // save the result
+    pNode->Volume = Dec_EdgeToInt( eNode );
+    return eNode;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrEva.c b/src/opt/rwr/rwrEva.c
new file mode 100644
index 00000000..0eb547f2
--- /dev/null
+++ b/src/opt/rwr/rwrEva.c
@@ -0,0 +1,588 @@
+/**CFile****************************************************************
+
+  FileName    [rwrDec.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Evaluation and decomposition procedures.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrDec.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+#include "dec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Dec_Graph_t * Rwr_CutEvaluate( Rwr_Man_t * p, Abc_Obj_t * pRoot, Cut_Cut_t * pCut, Vec_Ptr_t * vFaninsCur, int nNodesSaved, int LevelMax, int * pGainBest, int fPlaceEnable );
+static int Rwr_CutIsBoolean( Abc_Obj_t * pObj, Vec_Ptr_t * vLeaves );
+static int Rwr_CutCountNumNodes( Abc_Obj_t * pObj, Cut_Cut_t * pCut );
+static int Rwr_NodeGetDepth_rec( Abc_Obj_t * pObj, Vec_Ptr_t * vLeaves );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Performs rewriting for one node.]
+
+  Description [This procedure considers all the cuts computed for the node
+  and tries to rewrite each of them using the "forest" of different AIG
+  structures precomputed and stored in the RWR manager. 
+  Determines the best rewriting and computes the gain in the number of AIG
+  nodes in the final network. In the end, p->vFanins contains information 
+  about the best cut that can be used for rewriting, while p->pGraph gives 
+  the decomposition dag (represented using decomposition graph data structure).
+  Returns gain in the number of nodes or -1 if node cannot be rewritten.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_NodeRewrite( Rwr_Man_t * p, Cut_Man_t * pManCut, Abc_Obj_t * pNode, int fUpdateLevel, int fUseZeros, int fPlaceEnable )
+{
+    int fVeryVerbose = 0;
+    Dec_Graph_t * pGraph;
+    Cut_Cut_t * pCut;//, * pTemp;
+    Abc_Obj_t * pFanin;
+    unsigned uPhase, uTruthBest, uTruth;
+    char * pPerm;
+    int Required, nNodesSaved, nNodesSaveCur;
+    int i, GainCur, GainBest = -1;
+    int clk, clk2;//, Counter;
+
+    p->nNodesConsidered++;
+    // get the required times
+    Required = fUpdateLevel? Abc_ObjRequiredLevel(pNode) : ABC_INFINITY;
+
+    // get the node's cuts
+clk = clock();
+    pCut = (Cut_Cut_t *)Abc_NodeGetCutsRecursive( pManCut, pNode, 0, 0 );
+    assert( pCut != NULL );
+p->timeCut += clock() - clk;
+
+//printf( " %d", Rwr_CutCountNumNodes(pNode, pCut) );
+/*
+    Counter = 0;
+    for ( pTemp = pCut->pNext; pTemp; pTemp = pTemp->pNext )
+        Counter++;
+    printf( "%d ", Counter );
+*/
+    // go through the cuts
+clk = clock();
+    for ( pCut = pCut->pNext; pCut; pCut = pCut->pNext )
+    {
+        // consider only 4-input cuts
+        if ( pCut->nLeaves < 4 )
+            continue;
+//            Cut_CutPrint( pCut, 0 ), printf( "\n" );
+
+        // get the fanin permutation
+        uTruth = 0xFFFF & *Cut_CutReadTruth(pCut);
+        pPerm = p->pPerms4[ p->pPerms[uTruth] ];
+        uPhase = p->pPhases[uTruth];
+        // collect fanins with the corresponding permutation/phase
+        Vec_PtrClear( p->vFaninsCur );
+        Vec_PtrFill( p->vFaninsCur, (int)pCut->nLeaves, 0 );
+        for ( i = 0; i < (int)pCut->nLeaves; i++ )
+        {
+            pFanin = Abc_NtkObj( pNode->pNtk, pCut->pLeaves[pPerm[i]] );
+            if ( pFanin == NULL )
+                break;
+            pFanin = Abc_ObjNotCond(pFanin, ((uPhase & (1<<i)) > 0) );
+            Vec_PtrWriteEntry( p->vFaninsCur, i, pFanin );
+        }
+        if ( i != (int)pCut->nLeaves )
+        {
+            p->nCutsBad++;
+            continue;
+        }
+        p->nCutsGood++;
+
+        {
+            int Counter = 0;
+            Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+                if ( Abc_ObjFanoutNum(Abc_ObjRegular(pFanin)) == 1 )
+                    Counter++;
+            if ( Counter > 2 )
+                continue;
+        }
+
+clk2 = clock();
+/*
+        printf( "Considering: (" );
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            printf( "%d ", Abc_ObjFanoutNum(Abc_ObjRegular(pFanin)) );
+        printf( ")\n" );
+*/
+        // mark the fanin boundary 
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            Abc_ObjRegular(pFanin)->vFanouts.nSize++;
+
+        // label MFFC with current ID
+        Abc_NtkIncrementTravId( pNode->pNtk );
+        nNodesSaved = Abc_NodeMffcLabelAig( pNode );
+        // unmark the fanin boundary
+        Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+            Abc_ObjRegular(pFanin)->vFanouts.nSize--;
+p->timeMffc += clock() - clk2;
+
+        // evaluate the cut
+clk2 = clock();
+        pGraph = Rwr_CutEvaluate( p, pNode, pCut, p->vFaninsCur, nNodesSaved, Required, &GainCur, fPlaceEnable );
+p->timeEval += clock() - clk2;
+
+        // check if the cut is better than the current best one
+        if ( pGraph != NULL && GainBest < GainCur )
+        {
+            // save this form
+            nNodesSaveCur = nNodesSaved;
+            GainBest  = GainCur;
+            p->pGraph  = pGraph;
+            p->fCompl = ((uPhase & (1<<4)) > 0);
+            uTruthBest = 0xFFFF & *Cut_CutReadTruth(pCut);
+            // collect fanins in the
+            Vec_PtrClear( p->vFanins );
+            Vec_PtrForEachEntry( p->vFaninsCur, pFanin, i )
+                Vec_PtrPush( p->vFanins, pFanin );
+        }
+    }
+p->timeRes += clock() - clk;
+
+    if ( GainBest == -1 )
+        return -1;
+/*
+    if ( GainBest > 0 )
+    {
+        printf( "Class %d  ", p->pMap[uTruthBest] );
+        printf( "Gain = %d. Node %d : ", GainBest, pNode->Id );
+        Vec_PtrForEachEntry( p->vFanins, pFanin, i )
+            printf( "%d ", Abc_ObjRegular(pFanin)->Id );
+        Dec_GraphPrint( stdout, p->pGraph, NULL, NULL );
+        printf( "\n" );
+    }
+*/
+
+//    printf( "%d", nNodesSaveCur - GainBest );
+/*
+    if ( GainBest > 0 )
+    {
+        if ( Rwr_CutIsBoolean( pNode, p->vFanins ) )
+            printf( "b" );
+        else
+        {
+            printf( "Node %d : ", pNode->Id );
+            Vec_PtrForEachEntry( p->vFanins, pFanin, i )
+                printf( "%d ", Abc_ObjRegular(pFanin)->Id );
+            printf( "a" );
+        }
+    }
+*/
+/*
+    if ( GainBest > 0 )
+        if ( p->fCompl )
+            printf( "c" );
+        else
+            printf( "." );
+*/
+
+    // copy the leaves
+    Vec_PtrForEachEntry( p->vFanins, pFanin, i )
+        Dec_GraphNode(p->pGraph, i)->pFunc = pFanin;
+/*
+    printf( "(" );
+    Vec_PtrForEachEntry( p->vFanins, pFanin, i )
+        printf( " %d", Abc_ObjRegular(pFanin)->vFanouts.nSize - 1 );
+    printf( " )  " );
+*/
+//    printf( "%d ", Rwr_NodeGetDepth_rec( pNode, p->vFanins ) );
+
+    p->nScores[p->pMap[uTruthBest]]++;
+    p->nNodesGained += GainBest;
+    if ( fUseZeros || GainBest > 0 )
+    {
+        p->nNodesRewritten++;
+    }
+
+    // report the progress
+    if ( fVeryVerbose && GainBest > 0 )
+    {
+        printf( "Node %6s :   ", Abc_ObjName(pNode) );
+        printf( "Fanins = %d. ", p->vFanins->nSize );
+        printf( "Save = %d.  ", nNodesSaveCur );
+        printf( "Add = %d.  ",  nNodesSaveCur-GainBest );
+        printf( "GAIN = %d.  ", GainBest );
+        printf( "Cone = %d.  ", p->pGraph? Dec_GraphNodeNum(p->pGraph) : 0 );
+        printf( "Class = %d.  ", p->pMap[uTruthBest] );
+        printf( "\n" );
+    }
+    return GainBest;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Evaluates the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Dec_Graph_t * Rwr_CutEvaluate( Rwr_Man_t * p, Abc_Obj_t * pRoot, Cut_Cut_t * pCut, Vec_Ptr_t * vFaninsCur, int nNodesSaved, int LevelMax, int * pGainBest, int fPlaceEnable )
+{
+    Vec_Ptr_t * vSubgraphs;
+    Dec_Graph_t * pGraphBest, * pGraphCur;
+    Rwr_Node_t * pNode, * pFanin;
+    int nNodesAdded, GainBest, i, k;
+    unsigned uTruth;
+    float CostBest;//, CostCur;
+    // find the matching class of subgraphs
+    uTruth = 0xFFFF & *Cut_CutReadTruth(pCut);
+    vSubgraphs = Vec_VecEntry( p->vClasses, p->pMap[uTruth] );
+    p->nSubgraphs += vSubgraphs->nSize;
+    // determine the best subgraph
+    GainBest = -1;
+    CostBest = ABC_INFINITY;
+    Vec_PtrForEachEntry( vSubgraphs, pNode, i )
+    {
+        // get the current graph
+        pGraphCur = (Dec_Graph_t *)pNode->pNext;
+        // copy the leaves
+        Vec_PtrForEachEntry( vFaninsCur, pFanin, k )
+            Dec_GraphNode(pGraphCur, k)->pFunc = pFanin;
+        // detect how many unlabeled nodes will be reused
+        nNodesAdded = Dec_GraphToNetworkCount( pRoot, pGraphCur, nNodesSaved, LevelMax );
+        if ( nNodesAdded == -1 )
+            continue;
+        assert( nNodesSaved >= nNodesAdded );
+/*
+        // evaluate the cut
+        if ( fPlaceEnable )
+        {
+            extern float Abc_PlaceEvaluateCut( Abc_Obj_t * pRoot, Vec_Ptr_t * vFanins );
+
+            float Alpha = 0.5; // ???
+            float PlaceCost;
+
+            // get the placement cost of the cut
+            PlaceCost = Abc_PlaceEvaluateCut( pRoot, vFaninsCur );
+
+            // get the weigted cost of the cut
+            CostCur = nNodesSaved - nNodesAdded + Alpha * PlaceCost;
+
+            // do not allow uphill moves
+            if ( nNodesSaved - nNodesAdded < 0 )
+                continue;
+
+            // decide what cut to use
+            if ( CostBest > CostCur )
+            {
+                GainBest   = nNodesSaved - nNodesAdded; // pure node cost
+                CostBest   = CostCur;                   // cost with placement
+                pGraphBest = pGraphCur;                 // subgraph to be used for rewriting
+
+                // score the graph
+                if ( nNodesSaved - nNodesAdded > 0 )
+                {
+                    pNode->nScore++;
+                    pNode->nGain += GainBest;
+                    pNode->nAdded += nNodesAdded;
+                }
+            }
+        }
+        else
+*/
+        {
+            // count the gain at this node
+            if ( GainBest < nNodesSaved - nNodesAdded )
+            {
+                GainBest   = nNodesSaved - nNodesAdded;
+                pGraphBest = pGraphCur;
+
+                // score the graph
+                if ( nNodesSaved - nNodesAdded > 0 )
+                {
+                    pNode->nScore++;
+                    pNode->nGain += GainBest;
+                    pNode->nAdded += nNodesAdded;
+                }
+            }
+        }
+    }
+    if ( GainBest == -1 )
+        return NULL;
+    *pGainBest = GainBest;
+    return pGraphBest;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks the type of the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_CutIsBoolean_rec( Abc_Obj_t * pObj, Vec_Ptr_t * vLeaves, int fMarkA )
+{
+    if ( Vec_PtrFind(vLeaves, pObj) >= 0 || Vec_PtrFind(vLeaves, Abc_ObjNot(pObj)) >= 0 )
+    {
+        if ( fMarkA )
+            pObj->fMarkA = 1;
+        else
+            pObj->fMarkB = 1;
+        return;
+    }
+    assert( !Abc_ObjIsCi(pObj) );
+    Rwr_CutIsBoolean_rec( Abc_ObjFanin0(pObj), vLeaves, fMarkA );
+    Rwr_CutIsBoolean_rec( Abc_ObjFanin1(pObj), vLeaves, fMarkA );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Checks the type of the cut.]
+
+  Description [Returns 1(0) if the cut is Boolean (algebraic).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_CutIsBoolean( Abc_Obj_t * pObj, Vec_Ptr_t * vLeaves )
+{
+    Abc_Obj_t * pTemp;
+    int i, RetValue;
+    Vec_PtrForEachEntry( vLeaves, pTemp, i )
+    {
+        pTemp = Abc_ObjRegular(pTemp);
+        assert( !pTemp->fMarkA && !pTemp->fMarkB );
+    }
+    Rwr_CutIsBoolean_rec( Abc_ObjFanin0(pObj), vLeaves, 1 );
+    Rwr_CutIsBoolean_rec( Abc_ObjFanin1(pObj), vLeaves, 0 );
+    RetValue = 0;
+    Vec_PtrForEachEntry( vLeaves, pTemp, i )
+    {
+        pTemp = Abc_ObjRegular(pTemp);
+        RetValue |= pTemp->fMarkA && pTemp->fMarkB;
+        pTemp->fMarkA = pTemp->fMarkB = 0;
+    }
+    return RetValue;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Count the nodes in the cut space of a node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_CutCountNumNodes_rec( Abc_Obj_t * pObj, Cut_Cut_t * pCut, Vec_Ptr_t * vNodes )
+{
+    int i;
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+        if ( pCut->pLeaves[i] == pObj->Id )
+        {
+            // check if the node is collected
+            if ( pObj->fMarkC == 0 )
+            {
+                pObj->fMarkC = 1;
+                Vec_PtrPush( vNodes, pObj );
+            }
+            return;
+        }
+    assert( Abc_ObjIsNode(pObj) );
+    // check if the node is collected
+    if ( pObj->fMarkC == 0 )
+    {
+        pObj->fMarkC = 1;
+        Vec_PtrPush( vNodes, pObj );
+    }
+    // traverse the fanins
+    Rwr_CutCountNumNodes_rec( Abc_ObjFanin0(pObj), pCut, vNodes );
+    Rwr_CutCountNumNodes_rec( Abc_ObjFanin1(pObj), pCut, vNodes );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Count the nodes in the cut space of a node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_CutCountNumNodes( Abc_Obj_t * pObj, Cut_Cut_t * pCut )
+{
+    Vec_Ptr_t * vNodes;
+    int i, Counter;
+    // collect all nodes
+    vNodes = Vec_PtrAlloc( 100 );
+    for ( pCut = pCut->pNext; pCut; pCut = pCut->pNext )
+        Rwr_CutCountNumNodes_rec( pObj, pCut, vNodes );
+    // clean all nodes
+    Vec_PtrForEachEntry( vNodes, pObj, i )
+        pObj->fMarkC = 0;
+    // delete and return
+    Counter = Vec_PtrSize(vNodes);
+    Vec_PtrFree( vNodes );
+    return Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns depth of the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_NodeGetDepth_rec( Abc_Obj_t * pObj, Vec_Ptr_t * vLeaves )
+{
+    Abc_Obj_t * pLeaf;
+    int i, Depth0, Depth1;
+    if ( Abc_ObjIsCi(pObj) )
+        return 0;
+    Vec_PtrForEachEntry( vLeaves, pLeaf, i )
+        if ( pObj == Abc_ObjRegular(pLeaf) )
+            return 0;
+    Depth0 = Rwr_NodeGetDepth_rec( Abc_ObjFanin0(pObj), vLeaves );
+    Depth1 = Rwr_NodeGetDepth_rec( Abc_ObjFanin1(pObj), vLeaves );
+    return 1 + ABC_MAX( Depth0, Depth1 );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ScoresClean( Rwr_Man_t * p )
+{
+    Vec_Ptr_t * vSubgraphs;
+    Rwr_Node_t * pNode;
+    int i, k;
+    for ( i = 0; i < p->vClasses->nSize; i++ )
+    {
+        vSubgraphs = Vec_VecEntry( p->vClasses, i );
+        Vec_PtrForEachEntry( vSubgraphs, pNode, k )
+            pNode->nScore = pNode->nGain = pNode->nAdded = 0;
+    }
+}
+
+static int Gains[222];
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_ScoresCompare( int * pNum1, int * pNum2 )
+{
+    if ( Gains[*pNum1] > Gains[*pNum2] )
+        return -1;
+    if ( Gains[*pNum1] < Gains[*pNum2] )
+        return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ScoresReport( Rwr_Man_t * p )
+{
+    extern void Ivy_TruthDsdComputePrint( unsigned uTruth );
+    int Perm[222];
+    Vec_Ptr_t * vSubgraphs;
+    Rwr_Node_t * pNode;
+    int i, iNew, k;
+    unsigned uTruth;
+    // collect total gains
+    assert( p->vClasses->nSize == 222 );
+    for ( i = 0; i < p->vClasses->nSize; i++ )
+    {
+        Perm[i] = i;
+        Gains[i] = 0;
+        vSubgraphs = Vec_VecEntry( p->vClasses, i );
+        Vec_PtrForEachEntry( vSubgraphs, pNode, k )
+            Gains[i] += pNode->nGain;
+    }
+    // sort the gains
+    qsort( Perm, 222, sizeof(int), (int (*)(const void *, const void *))Rwr_ScoresCompare );
+
+    // print classes
+    for ( i = 0; i < p->vClasses->nSize; i++ )
+    {
+        iNew = Perm[i];
+        if ( Gains[iNew] == 0 )
+            break;
+        vSubgraphs = Vec_VecEntry( p->vClasses, iNew );
+        printf( "CLASS %3d: Subgr = %3d. Total gain = %6d.  ", iNew, Vec_PtrSize(vSubgraphs), Gains[iNew] );
+        uTruth = (unsigned)p->pMapInv[iNew];
+        Extra_PrintBinary( stdout, &uTruth, 16 );
+        printf( "  " );
+        Ivy_TruthDsdComputePrint( (unsigned)p->pMapInv[iNew] | ((unsigned)p->pMapInv[iNew] << 16) );
+        Vec_PtrForEachEntry( vSubgraphs, pNode, k )
+        {
+            if ( pNode->nScore == 0 )
+                continue;
+            printf( "    %2d: S=%5d. A=%5d. G=%6d. ", k, pNode->nScore, pNode->nAdded, pNode->nGain );
+            Dec_GraphPrint( stdout, (Dec_Graph_t *)pNode->pNext, NULL, NULL );
+        }
+    }
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrExp.c b/src/opt/rwr/rwrExp.c
new file mode 100644
index 00000000..2d00bb1c
--- /dev/null
+++ b/src/opt/rwr/rwrExp.c
@@ -0,0 +1,333 @@
+/**CFile****************************************************************
+
+  FileName    [rwrExp.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Computation of practically used NN-classes of 4-input cuts.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrExp.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Rwr_Man4_t_ Rwr_Man4_t;
+struct Rwr_Man4_t_
+{
+    // internal lookups
+    int                nFuncs;           // the number of four-var functions
+    unsigned short *   puCanons;         // canonical forms
+    int *              pnCounts;         // the counters of functions in each class
+    int                nConsidered;      // the number of nodes considered
+    int                nClasses;         // the number of NN classes
+};
+
+typedef struct Rwr_Man5_t_ Rwr_Man5_t;
+struct Rwr_Man5_t_
+{
+    // internal lookups
+    stmm_table *       tTableNN;         // the NN canonical forms
+    stmm_table *       tTableNPN;        // the NPN canonical forms
+};
+
+static Rwr_Man4_t * s_pManRwrExp4 = NULL;
+static Rwr_Man5_t * s_pManRwrExp5 = NULL;
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_Man4ExploreStart()
+{
+    Rwr_Man4_t * p;
+    p = ALLOC( Rwr_Man4_t, 1 );
+    memset( p, 0, sizeof(Rwr_Man4_t) );
+    // canonical forms
+    p->nFuncs    = (1<<16);
+    // canonical forms, phases, perms
+    Extra_Truth4VarNPN( &p->puCanons, NULL, NULL, NULL );
+    // counters
+    p->pnCounts  = ALLOC( int, p->nFuncs );
+    memset( p->pnCounts, 0, sizeof(int) * p->nFuncs );
+    s_pManRwrExp4 = p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_Man4ExploreCount( unsigned uTruth )
+{
+    assert( uTruth < (1<<16) );
+    s_pManRwrExp4->pnCounts[ s_pManRwrExp4->puCanons[uTruth] ]++;    
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_Man4ExplorePrint()
+{
+    FILE * pFile;
+    int i, CountMax, CountWrite, nCuts, nClasses;
+    int * pDistrib;
+    int * pReprs;
+    // find the max number of occurences
+    nCuts = nClasses = 0;
+    CountMax = 0;
+    for ( i = 0; i < s_pManRwrExp4->nFuncs; i++ )
+    {
+        if ( CountMax < s_pManRwrExp4->pnCounts[i] )
+            CountMax = s_pManRwrExp4->pnCounts[i];
+        nCuts += s_pManRwrExp4->pnCounts[i];
+        if ( s_pManRwrExp4->pnCounts[i] > 0 )
+            nClasses++;
+    }
+    printf( "Number of cuts considered       = %8d.\n", nCuts );
+    printf( "Classes occurring at least once = %8d.\n", nClasses );
+    // print the distribution of classes
+    pDistrib = ALLOC( int, CountMax + 1 );
+    pReprs   = ALLOC( int, CountMax + 1 );
+    memset( pDistrib, 0, sizeof(int)*(CountMax + 1) );
+    for ( i = 0; i < s_pManRwrExp4->nFuncs; i++ )
+    {
+        pDistrib[ s_pManRwrExp4->pnCounts[i] ]++;
+        pReprs[ s_pManRwrExp4->pnCounts[i] ] = i;
+    }
+
+    printf( "Occurence = %6d.  Num classes = %4d.  \n", 0, 2288-nClasses );
+    for ( i = 1; i <= CountMax; i++ )
+        if ( pDistrib[i] )
+        {
+            printf( "Occurence = %6d.  Num classes = %4d.  Repr = ", i, pDistrib[i] );
+            Extra_PrintBinary( stdout, (unsigned*)&(pReprs[i]), 16 ); 
+            printf( "\n" );
+        }
+    free( pDistrib );
+    free( pReprs );
+    // write into a file all classes above limit (5)
+    CountWrite = 0;
+    pFile = fopen( "npnclass_stats4.txt", "w" );
+    for ( i = 0; i < s_pManRwrExp4->nFuncs; i++ )
+        if ( s_pManRwrExp4->pnCounts[i] > 0 )
+        {
+            Extra_PrintHex( pFile, i, 4 );
+            fprintf( pFile, " %10d\n", s_pManRwrExp4->pnCounts[i] );
+//            fprintf( pFile, "%d ", i );
+            CountWrite++;
+        }
+    fclose( pFile );
+    printf( "%d classes written into file \"%s\".\n", CountWrite, "npnclass_stats4.txt" );
+}
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_Man5ExploreStart()
+{
+    Rwr_Man5_t * p;
+    p = ALLOC( Rwr_Man5_t, 1 );
+    memset( p, 0, sizeof(Rwr_Man5_t) );
+    p->tTableNN  = stmm_init_table( st_numcmp, st_numhash );
+    p->tTableNPN = stmm_init_table( st_numcmp, st_numhash );
+    s_pManRwrExp5 = p;
+
+//Extra_PrintHex( stdout, Extra_TruthCanonNPN( 0x0000FFFF, 5 ), 5 );
+//printf( "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_Man5ExploreCount( unsigned uTruth )
+{
+    int * pCounter;
+    if ( !stmm_find_or_add( s_pManRwrExp5->tTableNN, (char *)uTruth, (char***)&pCounter ) )
+        *pCounter = 0;
+    (*pCounter)++;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Collects stats about 4-var functions appearing in netlists.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwt_Man5ExplorePrint()
+{
+    FILE * pFile;
+    stmm_generator * gen;
+    int i, CountMax, nCuts, Counter;
+    int * pDistrib;
+    unsigned * pReprs;
+    unsigned uTruth, uTruthC;
+    int clk = clock();
+    Vec_Int_t * vClassesNN, * vClassesNPN;
+
+    // find the max number of occurences
+    nCuts = 0;
+    CountMax = 0;
+    stmm_foreach_item( s_pManRwrExp5->tTableNN, gen, (char **)&uTruth, (char **)&Counter )
+    {
+        nCuts += Counter;
+        if ( CountMax < Counter )
+            CountMax = Counter;
+    }
+    printf( "Number of cuts considered       = %8d.\n", nCuts );
+    printf( "Classes occurring at least once = %8d.\n", stmm_count(s_pManRwrExp5->tTableNN) );
+    printf( "The largest number of occurence = %8d.\n", CountMax );
+
+    // print the distribution of classes
+    pDistrib = ALLOC( int, CountMax + 1 );
+    pReprs   = ALLOC( unsigned, CountMax + 1 );
+    memset( pDistrib, 0, sizeof(int)*(CountMax + 1) );
+    stmm_foreach_item( s_pManRwrExp5->tTableNN, gen, (char **)&uTruth, (char **)&Counter )
+    {
+        assert( Counter <= CountMax );
+        pDistrib[ Counter ]++;
+        pReprs[ Counter ] = uTruth;
+    }
+
+    for ( i = 1; i <= CountMax; i++ )
+        if ( pDistrib[i] )
+        {
+            printf( "Occurence = %6d.  Num classes = %4d.  Repr = ", i, pDistrib[i] );
+            Extra_PrintBinary( stdout, pReprs + i, 32 ); 
+            printf( "\n" );
+        }
+    free( pDistrib );
+    free( pReprs );
+
+
+    // put them into an array
+    vClassesNN = Vec_IntAlloc( stmm_count(s_pManRwrExp5->tTableNN) );
+    stmm_foreach_item( s_pManRwrExp5->tTableNN, gen, (char **)&uTruth, NULL )
+        Vec_IntPush( vClassesNN, (int)uTruth );
+    Vec_IntSortUnsigned( vClassesNN );
+
+    // write into a file all classes
+    pFile = fopen( "nnclass_stats5.txt", "w" );
+    Vec_IntForEachEntry( vClassesNN, uTruth, i )
+    {
+        if ( !stmm_lookup( s_pManRwrExp5->tTableNN, (char *)uTruth, (char **)&Counter ) )
+        {
+            assert( 0 );
+        }
+        Extra_PrintHex( pFile, uTruth, 5 );
+        fprintf( pFile, " %10d\n", Counter );
+    }
+    fclose( pFile );
+    printf( "%d classes written into file \"%s\".\n", vClassesNN->nSize, "nnclass_stats5.txt" );
+
+
+clk = clock();
+    // how many NPN classes exist?
+    Vec_IntForEachEntry( vClassesNN, uTruth, i )
+    {
+        int * pCounter;
+        uTruthC = Extra_TruthCanonNPN( uTruth, 5 );
+        if ( !stmm_find_or_add( s_pManRwrExp5->tTableNPN, (char *)uTruthC, (char***)&pCounter ) )
+            *pCounter = 0;
+        if ( !stmm_lookup( s_pManRwrExp5->tTableNN, (char *)uTruth, (char **)&Counter ) )
+        {
+            assert( 0 );
+        }
+        (*pCounter) += Counter;
+    }
+    printf( "The numbe of NPN classes = %d.\n", stmm_count(s_pManRwrExp5->tTableNPN) );
+PRT( "Computing NPN classes", clock() - clk );
+
+    // put them into an array
+    vClassesNPN = Vec_IntAlloc( stmm_count(s_pManRwrExp5->tTableNPN) );
+    stmm_foreach_item( s_pManRwrExp5->tTableNPN, gen, (char **)&uTruth, NULL )
+        Vec_IntPush( vClassesNPN, (int)uTruth );
+    Vec_IntSortUnsigned( vClassesNPN );
+
+    // write into a file all classes
+    pFile = fopen( "npnclass_stats5.txt", "w" );
+    Vec_IntForEachEntry( vClassesNPN, uTruth, i )
+    {
+        if ( !stmm_lookup( s_pManRwrExp5->tTableNPN, (char *)uTruth, (char **)&Counter ) )
+        {
+            assert( 0 );
+        }
+        Extra_PrintHex( pFile, uTruth, 5 );
+        fprintf( pFile, " %10d\n", Counter );
+    }
+    fclose( pFile );
+    printf( "%d classes written into file \"%s\".\n", vClassesNPN->nSize, "npnclass_stats5.txt" );
+
+
+    // can they be uniquely characterized?
+
+}
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrLib.c b/src/opt/rwr/rwrLib.c
new file mode 100644
index 00000000..1cdf350e
--- /dev/null
+++ b/src/opt/rwr/rwrLib.c
@@ -0,0 +1,362 @@
+/**CFile****************************************************************
+
+  FileName    [rwrLib.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    []
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrLib.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static Rwr_Node_t *        Rwr_ManTryNode( Rwr_Man_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume );
+static void                Rwr_MarkUsed_rec( Rwr_Man_t * p, Rwr_Node_t * pNode );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Precomputes the forest in the manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManPrecompute( Rwr_Man_t * p )
+{
+    Rwr_Node_t * p0, * p1;
+    int i, k, Level, Volume;
+    int LevelOld = -1;
+    int nNodes;
+
+    Vec_PtrForEachEntryStart( p->vForest, p0, i, 1 )
+    Vec_PtrForEachEntryStart( p->vForest, p1, k, 1 )
+    {
+        if ( LevelOld < (int)p0->Level )
+        {
+            LevelOld = p0->Level;
+            printf( "Starting level %d  (at %d nodes).\n", LevelOld+1, i );
+            printf( "Considered = %5d M.   Found = %8d.   Classes = %6d.   Trying %7d.\n", 
+                p->nConsidered/1000000, p->vForest->nSize, p->nClasses, i );
+        }
+
+        if ( k == i )
+            break;
+//        if ( p0->Level + p1->Level > 6 ) // hard
+//            break;
+
+        if ( p0->Level + p1->Level > 5 ) // easy 
+            break;
+
+//        if ( p0->Level + p1->Level > 6 || (p0->Level == 3 && p1->Level == 3) )
+//            break;
+
+        // compute the level and volume of the new nodes
+        Level  = 1 + ABC_MAX( p0->Level, p1->Level );
+        Volume = 1 + Rwr_ManNodeVolume( p, p0, p1 );
+        // try four different AND nodes
+        Rwr_ManTryNode( p,         p0 ,         p1 , 0, Level, Volume );
+        Rwr_ManTryNode( p, Rwr_Not(p0),         p1 , 0, Level, Volume );
+        Rwr_ManTryNode( p,         p0 , Rwr_Not(p1), 0, Level, Volume );
+        Rwr_ManTryNode( p, Rwr_Not(p0), Rwr_Not(p1), 0, Level, Volume );
+        // try EXOR
+        Rwr_ManTryNode( p,         p0 ,         p1 , 1, Level, Volume + 1 );
+        // report the progress
+        if ( p->nConsidered % 50000000 == 0 )
+            printf( "Considered = %5d M.   Found = %8d.   Classes = %6d.   Trying %7d.\n", 
+                p->nConsidered/1000000, p->vForest->nSize, p->nClasses, i );
+        // quit after some time
+        if ( p->vForest->nSize == RWR_LIMIT + 5 )
+        {
+            printf( "Considered = %5d M.   Found = %8d.   Classes = %6d.   Trying %7d.\n", 
+                p->nConsidered/1000000, p->vForest->nSize, p->nClasses, i );
+            goto save;
+        }
+    }
+save :
+
+    // mark the relevant ones
+    Rwr_ManIncTravId( p );
+    k = 5;
+    nNodes = 0;
+    Vec_PtrForEachEntryStart( p->vForest, p0, i, 5 )
+        if ( p0->uTruth == p->puCanons[p0->uTruth] )
+        {
+            Rwr_MarkUsed_rec( p, p0 );
+            nNodes++;
+        }
+
+    // compact the array by throwing away non-canonical
+    k = 5;
+    Vec_PtrForEachEntryStart( p->vForest, p0, i, 5 )
+        if ( p0->fUsed )
+        {
+            p->vForest->pArray[k] = p0;
+            p0->Id = k++;
+        }
+    p->vForest->nSize = k;
+    printf( "Total canonical = %4d. Total used = %5d.\n", nNodes, p->vForest->nSize );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Node_t * Rwr_ManTryNode( Rwr_Man_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume )
+{
+    Rwr_Node_t * pOld, * pNew, ** ppPlace;
+    unsigned uTruth;
+    // compute truth table, level, volume
+    p->nConsidered++;
+    if ( fExor )
+    {
+//        printf( "Considering EXOR of %d and %d.\n", p0->Id, p1->Id );
+        uTruth = (p0->uTruth ^ p1->uTruth);
+    }
+    else
+        uTruth = (Rwr_IsComplement(p0)? ~Rwr_Regular(p0)->uTruth : Rwr_Regular(p0)->uTruth) & 
+                 (Rwr_IsComplement(p1)? ~Rwr_Regular(p1)->uTruth : Rwr_Regular(p1)->uTruth) & 0xFFFF;
+    // skip non-practical classes
+    if ( Level > 2 && !p->pPractical[p->puCanons[uTruth]] )
+        return NULL;
+    // enumerate through the nodes with the same canonical form
+    ppPlace = p->pTable + uTruth;
+    for ( pOld = *ppPlace; pOld; ppPlace = &pOld->pNext, pOld = pOld->pNext )
+    {
+        if ( pOld->Level <  (unsigned)Level && pOld->Volume < (unsigned)Volume )
+            return NULL;
+        if ( pOld->Level == (unsigned)Level && pOld->Volume < (unsigned)Volume )
+            return NULL;
+//        if ( pOld->Level <  (unsigned)Level && pOld->Volume == (unsigned)Volume )
+//            return NULL;
+    }
+/*
+    // enumerate through the nodes with the opposite polarity
+    for ( pOld = p->pTable[~uTruth & 0xFFFF]; pOld; pOld = pOld->pNext )
+    {
+        if ( pOld->Level <  (unsigned)Level && pOld->Volume < (unsigned)Volume )
+            return NULL;
+        if ( pOld->Level == (unsigned)Level && pOld->Volume < (unsigned)Volume )
+            return NULL;
+//        if ( pOld->Level <  (unsigned)Level && pOld->Volume == (unsigned)Volume )
+//            return NULL;
+    }
+*/
+    // count the classes
+    if ( p->pTable[uTruth] == NULL && p->puCanons[uTruth] == uTruth )
+        p->nClasses++;
+    // create the new node
+    pNew = (Rwr_Node_t *)Extra_MmFixedEntryFetch( p->pMmNode );
+    pNew->Id     = p->vForest->nSize;
+    pNew->TravId = 0;
+    pNew->uTruth = uTruth;
+    pNew->Level  = Level;
+    pNew->Volume = Volume;
+    pNew->fUsed  = 0;
+    pNew->fExor  = fExor;
+    pNew->p0     = p0;
+    pNew->p1     = p1;
+    pNew->pNext  = NULL;
+    Vec_PtrPush( p->vForest, pNew );
+    *ppPlace     = pNew;
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Node_t * Rwr_ManAddNode( Rwr_Man_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1, int fExor, int Level, int Volume )
+{
+    Rwr_Node_t * pNew;
+    unsigned uTruth;
+    // compute truth table, leve, volume
+    p->nConsidered++;
+    if ( fExor )
+        uTruth = (p0->uTruth ^ p1->uTruth);
+    else
+        uTruth = (Rwr_IsComplement(p0)? ~Rwr_Regular(p0)->uTruth : Rwr_Regular(p0)->uTruth) & 
+                 (Rwr_IsComplement(p1)? ~Rwr_Regular(p1)->uTruth : Rwr_Regular(p1)->uTruth) & 0xFFFF;
+    // create the new node
+    pNew = (Rwr_Node_t *)Extra_MmFixedEntryFetch( p->pMmNode );
+    pNew->Id     = p->vForest->nSize;
+    pNew->TravId = 0;
+    pNew->uTruth = uTruth;
+    pNew->Level  = Level;
+    pNew->Volume = Volume;
+    pNew->fUsed  = 0;
+    pNew->fExor  = fExor;
+    pNew->p0     = p0;
+    pNew->p1     = p1;
+    pNew->pNext  = NULL;
+    Vec_PtrPush( p->vForest, pNew );
+    // do not add if the node is not essential
+    if ( uTruth != p->puCanons[uTruth] )
+        return pNew;
+
+    // add to the list
+    p->nAdded++;
+    if ( p->pTable[uTruth] == NULL )
+        p->nClasses++;
+    Rwr_ListAddToTail( p->pTable + uTruth, pNew );
+    return pNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Node_t * Rwr_ManAddVar( Rwr_Man_t * p, unsigned uTruth, int fPrecompute )
+{
+    Rwr_Node_t * pNew;
+    pNew = (Rwr_Node_t *)Extra_MmFixedEntryFetch( p->pMmNode );
+    pNew->Id     = p->vForest->nSize;
+    pNew->TravId = 0;
+    pNew->uTruth = uTruth;
+    pNew->Level  = 0;
+    pNew->Volume = 0;
+    pNew->fUsed  = 1;
+    pNew->fExor  = 0;
+    pNew->p0     = NULL;
+    pNew->p1     = NULL;    
+    pNew->pNext  = NULL;
+    Vec_PtrPush( p->vForest, pNew );
+    if ( fPrecompute )
+        Rwr_ListAddToTail( p->pTable + uTruth, pNew );
+    return pNew;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_MarkUsed_rec( Rwr_Man_t * p, Rwr_Node_t * pNode )
+{
+    if ( pNode->fUsed || pNode->TravId == p->nTravIds )
+        return;
+    pNode->TravId = p->nTravIds;
+    pNode->fUsed = 1;
+    Rwr_MarkUsed_rec( p, Rwr_Regular(pNode->p0) );
+    Rwr_MarkUsed_rec( p, Rwr_Regular(pNode->p1) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_Trav_rec( Rwr_Man_t * p, Rwr_Node_t * pNode, int * pVolume )
+{
+    if ( pNode->fUsed || pNode->TravId == p->nTravIds )
+        return;
+    pNode->TravId = p->nTravIds;
+    (*pVolume)++;
+    if ( pNode->fExor )
+        (*pVolume)++;
+    Rwr_Trav_rec( p, Rwr_Regular(pNode->p0), pVolume );
+    Rwr_Trav_rec( p, Rwr_Regular(pNode->p1), pVolume );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_ManNodeVolume( Rwr_Man_t * p, Rwr_Node_t * p0, Rwr_Node_t * p1 )
+{
+    int Volume = 0;
+    Rwr_ManIncTravId( p );
+    Rwr_Trav_rec( p, p0, &Volume );
+    Rwr_Trav_rec( p, p1, &Volume );
+    return Volume;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManIncTravId( Rwr_Man_t * p )
+{
+    Rwr_Node_t * pNode;
+    int i;
+    if ( p->nTravIds++ < 0x8FFFFFFF )
+        return;
+    Vec_PtrForEachEntry( p->vForest, pNode, i )
+        pNode->TravId = 0;
+    p->nTravIds = 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrMan.c b/src/opt/rwr/rwrMan.c
new file mode 100644
index 00000000..87a080c7
--- /dev/null
+++ b/src/opt/rwr/rwrMan.c
@@ -0,0 +1,318 @@
+/**CFile****************************************************************
+
+  FileName    [rwrMan.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Rewriting manager.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrMan.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+#include "main.h"
+#include "dec.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts rewriting manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Rwr_Man_t * Rwr_ManStart( bool fPrecompute )
+{
+    Dec_Man_t * pManDec;
+    Rwr_Man_t * p;
+    int clk = clock();
+clk = clock();
+    p = ALLOC( Rwr_Man_t, 1 );
+    memset( p, 0, sizeof(Rwr_Man_t) );
+    p->nFuncs = (1<<16);
+    pManDec   = Abc_FrameReadManDec();
+    p->puCanons = pManDec->puCanons; 
+    p->pPhases  = pManDec->pPhases; 
+    p->pPerms   = pManDec->pPerms; 
+    p->pMap     = pManDec->pMap; 
+    // initialize practical NPN classes
+    p->pPractical  = Rwr_ManGetPractical( p );
+    // create the table
+    p->pTable = ALLOC( Rwr_Node_t *, p->nFuncs );
+    memset( p->pTable, 0, sizeof(Rwr_Node_t *) * p->nFuncs );
+    // create the elementary nodes
+    p->pMmNode  = Extra_MmFixedStart( sizeof(Rwr_Node_t) );
+    p->vForest  = Vec_PtrAlloc( 100 );
+    Rwr_ManAddVar( p, 0x0000, fPrecompute ); // constant 0
+    Rwr_ManAddVar( p, 0xAAAA, fPrecompute ); // var A
+    Rwr_ManAddVar( p, 0xCCCC, fPrecompute ); // var B
+    Rwr_ManAddVar( p, 0xF0F0, fPrecompute ); // var C
+    Rwr_ManAddVar( p, 0xFF00, fPrecompute ); // var D
+    p->nClasses = 5;
+    // other stuff
+    p->nTravIds   = 1;
+    p->pPerms4    = Extra_Permutations( 4 );
+    p->vLevNums   = Vec_IntAlloc( 50 );
+    p->vFanins    = Vec_PtrAlloc( 50 );
+    p->vFaninsCur = Vec_PtrAlloc( 50 );
+    p->vNodesTemp = Vec_PtrAlloc( 50 );
+    if ( fPrecompute )
+    {   // precompute subgraphs
+        Rwr_ManPrecompute( p );
+//        Rwr_ManPrint( p );
+        Rwr_ManWriteToArray( p );
+    }
+    else
+    {   // load saved subgraphs
+        Rwr_ManLoadFromArray( p, 0 );
+//        Rwr_ManPrint( p );
+        Rwr_ManPreprocess( p );
+    }
+p->timeStart = clock() - clk;
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops rewriting manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManStop( Rwr_Man_t * p )
+{
+    if ( p->vClasses )
+    {
+        Rwr_Node_t * pNode;
+        int i, k;
+        Vec_VecForEachEntry( p->vClasses, pNode, i, k )
+            Dec_GraphFree( (Dec_Graph_t *)pNode->pNext );
+    }
+    if ( p->vClasses )  Vec_VecFree( p->vClasses );
+    Vec_PtrFree( p->vNodesTemp );
+    Vec_PtrFree( p->vForest );
+    Vec_IntFree( p->vLevNums );
+    Vec_PtrFree( p->vFanins );
+    Vec_PtrFree( p->vFaninsCur );
+    Extra_MmFixedStop( p->pMmNode );
+    FREE( p->pMapInv );
+    free( p->pTable );
+    free( p->pPractical );
+    free( p->pPerms4 );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManPrintStats( Rwr_Man_t * p )
+{
+    int i, Counter = 0;
+    for ( i = 0; i < 222; i++ )
+        Counter += (p->nScores[i] > 0);
+
+    printf( "Rewriting statistics:\n" );
+    printf( "Total cuts tries  = %8d.\n", p->nCutsGood );
+    printf( "Bad cuts found    = %8d.\n", p->nCutsBad );
+    printf( "Total subgraphs   = %8d.\n", p->nSubgraphs );
+    printf( "Used NPN classes  = %8d.\n", Counter );
+    printf( "Nodes considered  = %8d.\n", p->nNodesConsidered );
+    printf( "Nodes rewritten   = %8d.\n", p->nNodesRewritten );
+    printf( "Gain              = %8d. (%6.2f %%).\n", p->nNodesBeg-p->nNodesEnd, 100.0*(p->nNodesBeg-p->nNodesEnd)/p->nNodesBeg );
+    PRT( "Start       ", p->timeStart );
+    PRT( "Cuts        ", p->timeCut );
+    PRT( "Resynthesis ", p->timeRes );
+    PRT( "    Mffc    ", p->timeMffc );
+    PRT( "    Eval    ", p->timeEval );
+    PRT( "Update      ", p->timeUpdate );
+    PRT( "TOTAL       ", p->timeTotal );
+
+/*
+    printf( "The scores are:\n" );
+    for ( i = 0; i < 222; i++ )
+        if ( p->nScores[i] > 0 )
+        {
+            extern void Ivy_TruthDsdComputePrint( unsigned uTruth );
+            printf( "%3d = %8d  canon = %5d  ", i, p->nScores[i], p->pMapInv[i] );
+            Ivy_TruthDsdComputePrint( (unsigned)p->pMapInv[i] | ((unsigned)p->pMapInv[i] << 16) );
+        }
+*/
+    printf( "\n" );
+
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManPrintStatsFile( Rwr_Man_t * p )
+{
+    FILE * pTable;
+    pTable = fopen( "stats.txt", "a+" );
+    fprintf( pTable, "%d ", p->nCutsGood );
+    fprintf( pTable, "%d ", p->nSubgraphs );
+    fprintf( pTable, "%d ", p->nNodesRewritten );
+    fprintf( pTable, "%d", p->nNodesGained );
+    fprintf( pTable, "\n" );
+    fclose( pTable );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void * Rwr_ManReadDecs( Rwr_Man_t * p )
+{
+    return p->pGraph;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Rwr_ManReadLeaves( Rwr_Man_t * p )
+{
+    return p->vFanins;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_ManReadCompl( Rwr_Man_t * p )
+{
+    return p->fCompl;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManAddTimeCuts( Rwr_Man_t * p, int Time )
+{
+    p->timeCut += Time;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManAddTimeUpdate( Rwr_Man_t * p, int Time )
+{
+    p->timeUpdate += Time;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the resynthesis manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManAddTimeTotal( Rwr_Man_t * p, int Time )
+{
+    p->timeTotal += Time;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Precomputes AIG subgraphs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_Precompute()
+{
+    Rwr_Man_t * p;
+    p = Rwr_ManStart( 1 );
+    Rwr_ManStop( p );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrPrint.c b/src/opt/rwr/rwrPrint.c
new file mode 100644
index 00000000..82ad2a90
--- /dev/null
+++ b/src/opt/rwr/rwrPrint.c
@@ -0,0 +1,266 @@
+/**CFile****************************************************************
+
+  FileName    [rwrCut.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Cut computation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrCut.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+ 
+/**Function*************************************************************
+
+  Synopsis    [Adds one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_Trav2_rec( Rwr_Man_t * p, Rwr_Node_t * pNode, int * pVolume )
+{
+    if ( pNode->fUsed || pNode->TravId == p->nTravIds )
+        return;
+    pNode->TravId = p->nTravIds;
+    (*pVolume)++;
+    Rwr_Trav2_rec( p, Rwr_Regular(pNode->p0), pVolume );
+    Rwr_Trav2_rec( p, Rwr_Regular(pNode->p1), pVolume );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the node to the end of the list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_GetBushVolume( Rwr_Man_t * p, int Entry, int * pVolume, int * pnFuncs )
+{
+    Rwr_Node_t * pNode;
+    int Volume = 0;
+    int nFuncs = 0;
+    Rwr_ManIncTravId( p );
+    for ( pNode = p->pTable[Entry]; pNode; pNode = pNode->pNext )
+    {
+        if ( pNode->uTruth != p->puCanons[pNode->uTruth] )
+            continue;
+        nFuncs++;
+        Rwr_Trav2_rec( p, pNode, &Volume );
+    }
+    *pVolume = Volume;
+    *pnFuncs = nFuncs;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the node to the end of the list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_GetBushSumOfVolumes( Rwr_Man_t * p, int Entry )
+{
+    Rwr_Node_t * pNode;
+    int Volume, VolumeTotal = 0;
+    for ( pNode = p->pTable[Entry]; pNode; pNode = pNode->pNext )
+    {
+        if ( pNode->uTruth != p->puCanons[pNode->uTruth] )
+            continue;
+        Volume = 0;
+        Rwr_ManIncTravId( p );
+        Rwr_Trav2_rec( p, pNode, &Volume );
+        VolumeTotal += Volume;
+    }
+    return VolumeTotal;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints one rwr node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_NodePrint_rec( FILE * pFile, Rwr_Node_t * pNode )
+{
+    assert( !Rwr_IsComplement(pNode) );
+
+    if ( pNode->Id == 0 )
+    {
+        fprintf( pFile, "Const1" );
+        return;
+    }
+
+    if ( pNode->Id < 5 )
+    {
+        fprintf( pFile, "%c", 'a' + pNode->Id - 1 );
+        return;
+    }
+
+    if ( Rwr_IsComplement(pNode->p0) )
+    {
+        if ( Rwr_Regular(pNode->p0)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+            fprintf( pFile, "\'" );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+            fprintf( pFile, ")\'" );
+        }
+    }
+    else
+    {
+        if ( Rwr_Regular(pNode->p0)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p0) );
+            fprintf( pFile, ")" );
+        }
+    }
+
+    if ( pNode->fExor )
+        fprintf( pFile, "+" );
+
+    if ( Rwr_IsComplement(pNode->p1) )
+    {
+        if ( Rwr_Regular(pNode->p1)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+            fprintf( pFile, "\'" );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+            fprintf( pFile, ")\'" );
+        }
+    }
+    else
+    {
+        if ( Rwr_Regular(pNode->p1)->Id < 5 )
+        {
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+        }
+        else
+        {
+            fprintf( pFile, "(" );
+            Rwr_NodePrint_rec( pFile, Rwr_Regular(pNode->p1) );
+            fprintf( pFile, ")" );
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints one rwr node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_NodePrint( FILE * pFile, Rwr_Man_t * p, Rwr_Node_t * pNode )
+{
+    unsigned uTruth;
+    fprintf( pFile, "%5d : ", pNode->Id );
+    Extra_PrintHex( pFile, pNode->uTruth, 4 );
+    fprintf( pFile, " tt=" );
+    uTruth = pNode->uTruth;
+    Extra_PrintBinary( pFile, &uTruth, 16 );
+//    fprintf( pFile, " cn=", pNode->Id );
+//    uTruth = p->puCanons[pNode->uTruth];
+//    Extra_PrintBinary( pFile, &uTruth, 16 );
+    fprintf( pFile, " lev=%d", pNode->Level );
+    fprintf( pFile, " vol=%d", pNode->Volume );
+    fprintf( pFile, "  " );
+    Rwr_NodePrint_rec( pFile, pNode );
+    fprintf( pFile, "\n" );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints one rwr node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManPrint( Rwr_Man_t * p )
+{
+    FILE * pFile;
+    Rwr_Node_t * pNode;
+    unsigned uTruth;
+    int Limit, Counter, Volume, nFuncs, i;
+    pFile = fopen( "graph_lib.txt", "w" );
+    Counter = 0;
+    Limit = (1 << 16);
+    for ( i = 0; i < Limit; i++ )
+    {
+        if ( p->pTable[i] == NULL )
+            continue;
+        if ( i != p->puCanons[i] )
+            continue;
+        fprintf( pFile, "\nClass %3d. Func %6d.  ", p->pMap[i], Counter++ );
+        Rwr_GetBushVolume( p, i, &Volume, &nFuncs );
+        fprintf( pFile, "Roots = %3d. Vol = %3d. Sum = %3d.  ", nFuncs, Volume, Rwr_GetBushSumOfVolumes(p, i) );
+        uTruth = i;
+        Extra_PrintBinary( pFile, &uTruth, 16 );
+        fprintf( pFile, "\n" );
+        for ( pNode = p->pTable[i]; pNode; pNode = pNode->pNext )
+            if ( pNode->uTruth == p->puCanons[pNode->uTruth] )
+                Rwr_NodePrint( pFile, p, pNode );
+    }
+    fclose( pFile );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrTemp.c b/src/opt/rwr/rwrTemp.c
new file mode 100644
index 00000000..3ffbd408
--- /dev/null
+++ b/src/opt/rwr/rwrTemp.c
@@ -0,0 +1,121 @@
+/**CFile****************************************************************
+
+  FileName    [rwrCut.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Cut computation.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrCut.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int pTruths[13719];
+static int pFreqs[13719];
+static int pPerm[13719];
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+ 
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Rwr_TempCompare( int * pNum1, int * pNum2 )
+{
+    int Freq1 = pFreqs[*pNum1];
+    int Freq2 = pFreqs[*pNum2];
+    if ( Freq1 < Freq2 )
+        return 1;
+    if ( Freq1 > Freq2 )
+        return -1;
+    return 0; 
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_Temp()
+{
+    char Buffer[32];
+    int nFuncs = 13719;
+    int nEntries = 100;
+    unsigned uTruth;
+    int i, k;
+    FILE * pFile;
+
+    pFile = fopen( "nnclass_stats5.txt", "r" );
+    for ( i = 0; i < 13719; i++ )
+    {
+        fscanf( pFile, "%s%d", Buffer, &pFreqs[i] );
+        Extra_ReadHexadecimal( &uTruth, Buffer+2, 5 );
+        pTruths[i] = uTruth;
+    }
+    fclose( pFile );
+
+    for ( i = 0; i < 13719; i++ )
+        pPerm[i] = i;
+
+    qsort( (void *)pPerm, 13719, sizeof(int), 
+            (int (*)(const void *, const void *)) Rwr_TempCompare );
+
+
+    pFile = fopen( "5npn_100.blif", "w" );
+    fprintf( pFile, "# Most frequent NPN classes of 5 vars.\n" );
+    fprintf( pFile, ".model 5npn\n" );
+    fprintf( pFile, ".inputs a b c d e\n" );
+    fprintf( pFile, ".outputs" );
+    for ( i = 0; i < nEntries; i++ )
+        fprintf( pFile, " %02d", i );
+    fprintf( pFile, "\n" );
+
+    for ( i = 0; i < nEntries; i++ )
+    {
+        fprintf( pFile, ".names a b c d e %02d\n", i );
+        uTruth = pTruths[pPerm[i]];
+        for ( k = 0; k < 32; k++ )
+            if ( uTruth & (1 << k) )
+            {
+                Extra_PrintBinary( pFile, &k, 5 );
+                fprintf( pFile, " 1\n" );
+            }
+    }
+    fprintf( pFile, ".end\n" );
+    fclose( pFile );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/rwr/rwrUtil.c b/src/opt/rwr/rwrUtil.c
new file mode 100644
index 00000000..b2add2bf
--- /dev/null
+++ b/src/opt/rwr/rwrUtil.c
@@ -0,0 +1,659 @@
+/**CFile****************************************************************
+
+  FileName    [rwrUtil.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [DAG-aware AIG rewriting package.]
+
+  Synopsis    [Various utilities.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: rwrUtil.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "rwr.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// precomputed data
+#ifdef _WIN32
+unsigned short s_RwrPracticalClasses[];
+unsigned short s_RwtAigSubgraphs[];
+#else
+static unsigned short s_RwrPracticalClasses[];
+static unsigned short s_RwtAigSubgraphs[];
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Writes data.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManWriteToArray( Rwr_Man_t * p )
+{
+    FILE * pFile;
+    Rwr_Node_t * pNode;
+    unsigned Entry0, Entry1;
+    int i, nEntries, clk = clock();
+    // prepare the buffer
+    nEntries = p->vForest->nSize - 5;
+    pFile = fopen( "npn4_aig_array.txt", "w" );
+    fprintf( pFile, "static unsigned short s_RwtAigSubgraphs[] = \n{" );
+    for ( i = 0; i < nEntries; i++ )
+    {
+        if ( i % 5 == 0 )
+            fprintf( pFile, "\n    " );
+        pNode = p->vForest->pArray[i+5];
+        Entry0 = (Rwr_Regular(pNode->p0)->Id << 1) | Rwr_IsComplement(pNode->p0);
+        Entry1 = (Rwr_Regular(pNode->p1)->Id << 1) | Rwr_IsComplement(pNode->p1);
+        Entry0 = (Entry0 << 1) | pNode->fExor;
+        Extra_PrintHex( pFile, Entry0, 4 );
+        fprintf( pFile, "," );
+        Extra_PrintHex( pFile, Entry1, 4 );
+        fprintf( pFile, ", " );
+    }
+    if ( i % 5 == 0 )
+        fprintf( pFile, "\n    " );
+    Extra_PrintHex( pFile, 0, 4 );
+    fprintf( pFile, "," );
+    Extra_PrintHex( pFile, 0, 4 );
+    fprintf( pFile, " \n};\n" );
+    fclose( pFile );
+    printf( "The number of nodes saved = %d.   ", nEntries );  PRT( "Saving", clock() - clk );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Loads data.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManLoadFromArray( Rwr_Man_t * p, int fVerbose )
+{
+    unsigned short * pArray = s_RwtAigSubgraphs;
+    Rwr_Node_t * p0, * p1;
+    unsigned Entry0, Entry1;
+    int Level, Volume, nEntries, fExor;
+    int i, clk = clock();
+
+    // reconstruct the forest
+    for ( i = 0; ; i++ )
+    {
+        Entry0 = pArray[2*i + 0];
+        Entry1 = pArray[2*i + 1];
+        if ( Entry0 == 0 && Entry1 == 0 )
+            break;
+        // get EXOR flag
+        fExor = (Entry0 & 1);
+        Entry0 >>= 1;
+        // get the nodes
+        p0 = p->vForest->pArray[Entry0 >> 1];
+        p1 = p->vForest->pArray[Entry1 >> 1];
+        // compute the level and volume of the new nodes
+        Level  = 1 + ABC_MAX( p0->Level, p1->Level );
+        Volume = 1 + Rwr_ManNodeVolume( p, p0, p1 );
+        // set the complemented attributes
+        p0 = Rwr_NotCond( p0, (Entry0 & 1) );
+        p1 = Rwr_NotCond( p1, (Entry1 & 1) );
+        // add the node
+//        Rwr_ManTryNode( p, p0, p1, Level, Volume );
+        Rwr_ManAddNode( p, p0, p1, fExor, Level, Volume + fExor );
+    }
+    nEntries = i - 1;
+    if ( fVerbose )
+    {
+        printf( "The number of classes = %d. Canonical nodes = %d.\n", p->nClasses, p->nAdded );
+        printf( "The number of nodes loaded = %d.  ", nEntries );  PRT( "Loading", clock() - clk );
+    }
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Writes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManWriteToFile( Rwr_Man_t * p, char * pFileName )
+{
+    FILE * pFile;
+    Rwr_Node_t * pNode;
+    unsigned * pBuffer;
+    int i, nEntries, clk = clock();
+    // prepare the buffer
+    nEntries = p->vForest->nSize - 5;
+    pBuffer = ALLOC( unsigned, nEntries * 2 );
+    for ( i = 0; i < nEntries; i++ )
+    {
+        pNode = p->vForest->pArray[i+5];
+        pBuffer[2*i + 0] = (Rwr_Regular(pNode->p0)->Id << 1) | Rwr_IsComplement(pNode->p0);
+        pBuffer[2*i + 1] = (Rwr_Regular(pNode->p1)->Id << 1) | Rwr_IsComplement(pNode->p1);
+        // save EXOR flag
+        pBuffer[2*i + 0] = (pBuffer[2*i + 0] << 1) | pNode->fExor;
+
+    }
+    pFile = fopen( pFileName, "wb" );
+    fwrite( &nEntries, sizeof(int), 1, pFile );
+    fwrite( pBuffer, sizeof(unsigned), nEntries * 2, pFile );
+    free( pBuffer );
+    fclose( pFile );
+    printf( "The number of nodes saved = %d.   ", nEntries );  PRT( "Saving", clock() - clk );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Loads data.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ManLoadFromFile( Rwr_Man_t * p, char * pFileName )
+{
+    FILE * pFile;
+    Rwr_Node_t * p0, * p1;
+    unsigned * pBuffer;
+    int Level, Volume, nEntries, fExor;
+    int i, clk = clock();
+
+    // load the data
+    pFile = fopen( pFileName, "rb" );
+    if ( pFile == NULL )
+    {
+        printf( "Rwr_ManLoadFromFile: Cannot open file \"%s\".\n", pFileName );
+        return;
+    }
+    fread( &nEntries, sizeof(int), 1, pFile );
+    pBuffer = ALLOC( unsigned, nEntries * 2 );
+    fread( pBuffer, sizeof(unsigned), nEntries * 2, pFile );
+    fclose( pFile );
+    // reconstruct the forest
+    for ( i = 0; i < nEntries; i++ )
+    {
+        // get EXOR flag
+        fExor = (pBuffer[2*i + 0] & 1);
+        pBuffer[2*i + 0] = (pBuffer[2*i + 0] >> 1);
+        // get the nodes
+        p0 = p->vForest->pArray[pBuffer[2*i + 0] >> 1];
+        p1 = p->vForest->pArray[pBuffer[2*i + 1] >> 1];
+        // compute the level and volume of the new nodes
+        Level  = 1 + ABC_MAX( p0->Level, p1->Level );
+        Volume = 1 + Rwr_ManNodeVolume( p, p0, p1 );
+        // set the complemented attributes
+        p0 = Rwr_NotCond( p0, (pBuffer[2*i + 0] & 1) );
+        p1 = Rwr_NotCond( p1, (pBuffer[2*i + 1] & 1) );
+        // add the node
+//        Rwr_ManTryNode( p, p0, p1, Level, Volume );
+        Rwr_ManAddNode( p, p0, p1, fExor, Level, Volume + fExor );
+    }
+    free( pBuffer );
+    printf( "The number of classes = %d. Canonical nodes = %d.\n", p->nClasses, p->nAdded );
+    printf( "The number of nodes loaded = %d.   ", nEntries );  PRT( "Loading", clock() - clk );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the node to the end of the list.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Rwr_ListAddToTail( Rwr_Node_t ** ppList, Rwr_Node_t * pNode )
+{
+    Rwr_Node_t * pTemp;
+    // find the last one
+    for ( pTemp = *ppList; pTemp; pTemp = pTemp->pNext )
+        ppList = &pTemp->pNext;
+    // attach at the end
+    *ppList = pNode;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Create practical classes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+char * Rwr_ManGetPractical( Rwr_Man_t * p )
+{
+    char * pPractical;
+    int i;
+    pPractical = ALLOC( char, p->nFuncs );
+    memset( pPractical, 0, sizeof(char) * p->nFuncs );
+    pPractical[0] = 1;
+    for ( i = 1; ; i++ )
+    {
+        if ( s_RwrPracticalClasses[i] == 0 )
+            break;
+        pPractical[ s_RwrPracticalClasses[i] ] = 1;
+    }
+    return pPractical;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+// the following 135 practical NPN classes of 4-variable functions were computed
+// by considering all 4-input cuts appearing in IWLS, MCNC, and ISCAS benchmarks
+static unsigned short s_RwrPracticalClasses[] = 
+{
+    0x0000, 0x0001, 0x0003, 0x0006, 0x0007, 0x000f, 0x0016, 0x0017, 0x0018, 0x0019, 0x001b, 
+    0x001e, 0x001f, 0x003c, 0x003d, 0x003f, 0x0069, 0x006b, 0x006f, 0x007e, 0x007f, 0x00ff, 
+    0x0116, 0x0118, 0x0119, 0x011a, 0x011b, 0x011e, 0x011f, 0x012c, 0x012d, 0x012f, 0x013c, 
+    0x013d, 0x013e, 0x013f, 0x0168, 0x0169, 0x016f, 0x017f, 0x0180, 0x0181, 0x0182, 0x0183, 
+    0x0186, 0x0189, 0x018b, 0x018f, 0x0198, 0x0199, 0x019b, 0x01a8, 0x01a9, 0x01aa, 0x01ab, 
+    0x01ac, 0x01ad, 0x01ae, 0x01af, 0x01bf, 0x01e9, 0x01ea, 0x01eb, 0x01ee, 0x01ef, 0x01fe, 
+    0x033c, 0x033d, 0x033f, 0x0356, 0x0357, 0x0358, 0x0359, 0x035a, 0x035b, 0x035f, 0x0368, 
+    0x0369, 0x036c, 0x036e, 0x037d, 0x03c0, 0x03c1, 0x03c3, 0x03c7, 0x03cf, 0x03d4, 0x03d5, 
+    0x03d7, 0x03d8, 0x03d9, 0x03dc, 0x03dd, 0x03de, 0x03fc, 0x0660, 0x0661, 0x0666, 0x0669, 
+    0x066f, 0x0676, 0x067e, 0x0690, 0x0696, 0x0697, 0x069f, 0x06b1, 0x06b6, 0x06f0, 0x06f2, 
+    0x06f6, 0x06f9, 0x0776, 0x0778, 0x07b0, 0x07b1, 0x07b4, 0x07bc, 0x07f0, 0x07f2, 0x07f8, 
+    0x0ff0, 0x1683, 0x1696, 0x1698, 0x169e, 0x16e9, 0x178e, 0x17e8, 0x18e7, 0x19e6, 0x1be4, 
+    0x1ee1, 0x3cc3, 0x6996, 0x0000
+};
+
+static unsigned short s_RwtAigSubgraphs[] = 
+{
+    0x0008,0x0002, 0x000a,0x0002, 0x0008,0x0003, 0x000a,0x0003, 0x0009,0x0002, 
+    0x000c,0x0002, 0x000e,0x0002, 0x000c,0x0003, 0x000e,0x0003, 0x000d,0x0002, 
+    0x000c,0x0004, 0x000e,0x0004, 0x000c,0x0005, 0x000e,0x0005, 0x000d,0x0004, 
+    0x0010,0x0002, 0x0012,0x0002, 0x0010,0x0003, 0x0012,0x0003, 0x0011,0x0002, 
+    0x0010,0x0004, 0x0012,0x0004, 0x0010,0x0005, 0x0012,0x0005, 0x0011,0x0004, 
+    0x0010,0x0006, 0x0012,0x0006, 0x0010,0x0007, 0x0012,0x0007, 0x0011,0x0006, 
+    0x0016,0x0005, 0x0014,0x0006, 0x0016,0x0006, 0x0014,0x0007, 0x0016,0x0007, 
+    0x0015,0x0006, 0x0014,0x0008, 0x0016,0x0008, 0x0014,0x0009, 0x0016,0x0009, 
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+    0x0259,0x0086, 0x0258,0x00c7, 0x0258,0x00df, 0x0259,0x00ec, 0x0258,0x00fc, 
+    0x025d,0x0024, 0x025d,0x00de, 0x0260,0x00f6, 0x0268,0x0009, 0x0269,0x0044, 
+    0x0268,0x00f3, 0x0268,0x00f9, 0x026d,0x003a, 0x0270,0x0068, 0x0275,0x003a, 
+    0x027a,0x0044, 0x0279,0x0044, 0x027e,0x007e, 0x0281,0x0044, 0x0285,0x0008, 
+    0x028d,0x0006, 0x028d,0x00d2, 0x0295,0x00cc, 0x0296,0x00f6, 0x0295,0x00f8, 
+    0x0299,0x0030, 0x029e,0x007e, 0x029d,0x0080, 0x02a6,0x008f, 0x02a6,0x0095, 
+    0x02aa,0x0029, 0x02aa,0x0030, 0x02b5,0x0008, 0x02b9,0x003a, 0x02bd,0x0004, 
+    0x02bd,0x00fc, 0x02c2,0x00b2, 0x02c1,0x00b4, 0x02c4,0x0029, 0x02c8,0x0029, 
+    0x02c8,0x0033, 0x02ca,0x003d, 0x02ce,0x0029, 0x02ce,0x0030, 0x02d2,0x0068, 
+    0x02d1,0x006a, 0x02d5,0x006a, 0x02d9,0x0008, 0x02de,0x012c, 0x02e2,0x012c, 
+    0x02e4,0x0009, 0x02e5,0x002a, 0x02e5,0x0056, 0x02e5,0x012c, 0x02ea,0x0029, 
+    0x02ea,0x0030, 0x02e9,0x0030, 0x02ec,0x0029, 0x02ec,0x0030, 0x02ee,0x012c, 
+    0x02f1,0x0068, 0x02f1,0x00b2, 0x02f1,0x0108, 0x02f1,0x012c, 0x02f6,0x0013, 
+    0x02f6,0x0015, 0x02f6,0x001f, 0x02f6,0x0030, 0x02f6,0x0065, 0x02f6,0x0067, 
+    0x02f6,0x009f, 0x02f6,0x00b6, 0x02f6,0x00b9, 0x02f6,0x00c0, 0x02f6,0x00cf, 
+    0x02f6,0x0107, 0x02f6,0x010b, 0x02f6,0x010f, 0x02f6,0x0115, 0x02f6,0x012d, 
+    0x02f6,0x0134, 0x02f6,0x0153, 0x02f6,0x0171, 0x02f6,0x0176, 0x02f8,0x0003, 
+    0x02fa,0x017b, 0x02fc,0x00ba, 0x02fc,0x00d3, 0x0302,0x0013, 0x0302,0x001f, 
+    0x0302,0x0030, 0x0302,0x005d, 0x0302,0x0065, 0x0302,0x0067, 0x0302,0x0099, 
+    0x0302,0x009f, 0x0302,0x00ad, 0x0302,0x00b9, 0x0302,0x00c0, 0x0302,0x00cf, 
+    0x0301,0x00d2, 0x0301,0x00fe, 0x0302,0x0107, 0x0302,0x010b, 0x0302,0x010f, 
+    0x0302,0x0117, 0x0302,0x0134, 0x0302,0x0153, 0x0302,0x0157, 0x0302,0x0176, 
+    0x0306,0x0029, 0x0308,0x00b2, 0x0309,0x00dc, 0x030d,0x00f8, 0x0312,0x00f3, 
+    0x0318,0x007e, 0x031d,0x0080, 0x0321,0x0008, 0x0321,0x0094, 0x0326,0x017b, 
+    0x0326,0x0181, 0x0329,0x012e, 0x032a,0x017b, 0x032a,0x0181, 0x032e,0x008f, 
+    0x032e,0x0095, 0x032e,0x00f3, 0x032e,0x00f9, 0x0332,0x0009, 0x0331,0x0008, 
+    0x0330,0x003d, 0x0330,0x0044, 0x0330,0x0053, 0x0332,0x008f, 0x0332,0x0095, 
+    0x0330,0x00b1, 0x0332,0x00f3, 0x0332,0x00f9, 0x0330,0x0127, 0x0332,0x017b, 
+    0x0332,0x0181, 0x033c,0x0013, 0x033c,0x001c, 0x033d,0x0086, 0x033d,0x00ec, 
+    0x033d,0x0172, 0x033e,0x019d, 0x0345,0x0002, 0x0344,0x008f, 0x0344,0x00f3, 
+    0x034d,0x0030, 0x0352,0x0033, 0x0354,0x0029, 0x0354,0x0030, 0x035a,0x0009, 
+    0x035a,0x017b, 0x035a,0x019b, 0x035a,0x01a2, 0x035e,0x0181, 0x0360,0x0009, 
+    0x0366,0x0009, 0x0364,0x0029, 0x0364,0x0030, 0x0364,0x0033, 0x0364,0x003a, 
+    0x0364,0x003d, 0x0364,0x0044, 0x0369,0x0030, 0x0370,0x0029, 0x0370,0x0030, 
+    0x0376,0x0033, 0x037a,0x0009, 0x037a,0x019b, 0x037a,0x01a2, 0x037c,0x0009, 
+    0x0382,0x0181, 0x0386,0x0009, 0x0384,0x0029, 0x0384,0x0030, 0x0384,0x0033, 
+    0x0384,0x003a, 0x0384,0x003d, 0x0384,0x0044, 0x038a,0x0044, 0x038a,0x009e, 
+    0x038a,0x0106, 0x038a,0x0198, 0x038d,0x010e, 0x038d,0x0152, 0x038d,0x0158, 
+    0x0392,0x009e, 0x0392,0x0106, 0x0392,0x0198, 0x0395,0x0086, 0x0395,0x009a, 
+    0x0395,0x00ec, 0x0395,0x0172, 0x0398,0x014e, 0x0398,0x0175, 0x0398,0x018d, 
+    0x039c,0x0023, 0x039c,0x0027, 0x039c,0x00ef, 0x039c,0x0139, 0x039c,0x0168, 
+    0x03a0,0x0019, 0x03a0,0x001d, 0x03a0,0x0023, 0x03a0,0x0027, 0x03a1,0x004e, 
+    0x03a4,0x0162, 0x03a4,0x0183, 0x03a8,0x0013, 0x03a8,0x0027, 0x03a8,0x0133, 
+    0x03a8,0x0148, 0x03a8,0x0181, 0x03ac,0x0013, 0x03ac,0x0027, 0x03b0,0x017b, 
+    0x03b0,0x0181, 0x03b4,0x004b, 0x03b4,0x00e0, 0x03b4,0x00fb, 0x03b8,0x000f, 
+    0x03b8,0x0013, 0x03b8,0x00ab, 0x03b8,0x00bf, 0x03b8,0x00d0, 0x03bd,0x00da, 
+    0x03bd,0x012c, 0x03c8,0x000f, 0x03c8,0x0013, 0x03c8,0x0019, 0x03c8,0x001d, 
+    0x03cd,0x0086, 0x03cd,0x00ec, 0x03cd,0x0172, 0x03d2,0x00e0, 0x03d2,0x00ef, 
+    0x03d2,0x0112, 0x03d2,0x0139, 0x03d2,0x0168, 0x03d6,0x017b, 0x03d6,0x0181, 
+    0x03da,0x0133, 0x03da,0x0148, 0x03e2,0x0023, 0x03e2,0x0027, 0x03e6,0x0027, 
+    0x03e6,0x0181, 0x03ee,0x017b, 0x03ee,0x0181, 0x03fe,0x003d, 0x0401,0x012a, 
+    0x0401,0x019e, 0x0405,0x01a0, 0x040a,0x000d, 0x040a,0x011f, 0x040a,0x016f, 
+    0x040d,0x012a, 0x0412,0x017b, 0x041a,0x0033, 0x041a,0x003d, 0x041a,0x0181, 
+    0x0421,0x0086, 0x0421,0x009a, 0x0421,0x00ec, 0x0421,0x0172, 0x042e,0x0205, 
+    0x043a,0x0205, 0x043e,0x017b, 0x0442,0x01f5, 0x044c,0x0007, 0x0452,0x0033, 
+    0x0452,0x01ce, 0x0452,0x01d0, 0x0452,0x01f1, 0x0452,0x01fb, 0x0452,0x0225, 
+    0x0454,0x0005, 0x045a,0x0033, 0x045a,0x0181, 0x045a,0x01ce, 0x045a,0x01d0, 
+    0x045a,0x01f1, 0x0469,0x01de, 0x046e,0x0181, 0x047a,0x01ce, 0x047a,0x01f1, 
+    0x0485,0x012c, 0x0489,0x012c, 0x0490,0x01d8, 0x0496,0x0033, 0x0496,0x003d, 
+    0x0498,0x008f, 0x0498,0x00f3, 0x049e,0x0044, 0x049e,0x0221, 0x04a1,0x0006, 
+    0x04a2,0x0044, 0x04a6,0x0221, 0x04a9,0x0004, 0x04ac,0x0027, 0x04b1,0x009a, 
+    0x04b6,0x0097, 0x04b8,0x0027, 0x04c6,0x0219, 0x04ca,0x017b, 0x04cc,0x004b, 
+    0x04d0,0x00ab, 0x04d6,0x017b, 0x04d8,0x000f, 0x04d8,0x0019, 0x04d8,0x0033, 
+    0x04d8,0x003d, 0x04de,0x003d, 0x04de,0x0103, 0x04de,0x018b, 0x04de,0x0231, 
+    0x04e2,0x0044, 0x04e2,0x009e, 0x04e2,0x0106, 0x04e2,0x0198, 0x04e5,0x01a4, 
+    0x04e5,0x01b6, 0x04ea,0x009e, 0x04ea,0x0106, 0x04ea,0x0198, 0x04ed,0x002e, 
+    0x04ed,0x0038, 0x04ed,0x00a2, 0x04f1,0x0086, 0x04f1,0x009a, 0x04f1,0x00ec, 
+    0x04f1,0x0172, 0x04f9,0x004e, 0x04f8,0x0229, 0x04f8,0x022d, 0x0500,0x023e, 
+    0x0504,0x0217, 0x0510,0x00f3, 0x0514,0x0043, 0x0514,0x004d, 0x0514,0x00c3, 
+    0x0514,0x013d, 0x0514,0x0215, 0x0514,0x0232, 0x0515,0x0260, 0x0519,0x002a, 
+    0x0518,0x0030, 0x0518,0x0067, 0x0518,0x00c9, 0x0518,0x01eb, 0x0518,0x01ef, 
+    0x051c,0x0139, 0x051c,0x0168, 0x0520,0x0027, 0x0526,0x014e, 0x0526,0x0175, 
+    0x0526,0x018d, 0x052d,0x0200, 0x0532,0x0021, 0x0532,0x00bf, 0x0532,0x00d0, 
+    0x0532,0x0239, 0x0532,0x0266, 0x053d,0x0024, 0x053d,0x00da, 0x054a,0x000f, 
+    0x054a,0x00ab, 0x054a,0x023a, 0x054e,0x0043, 0x054e,0x004d, 0x054e,0x00c3, 
+    0x054e,0x013d, 0x054e,0x0215, 0x054e,0x0232, 0x054e,0x029d, 0x0552,0x014e, 
+    0x0552,0x018d, 0x0556,0x00f3, 0x0556,0x01e4, 0x055a,0x0299, 0x055d,0x0086, 
+    0x055d,0x009a, 0x055d,0x00ec, 0x055d,0x0172, 0x0566,0x01dc, 0x0566,0x02a5, 
+    0x056d,0x020a, 0x057a,0x003d, 0x057a,0x01d4, 0x057a,0x01f3, 0x0579,0x025e, 
+    0x057e,0x0139, 0x057e,0x0168, 0x0581,0x0006, 0x0586,0x017b, 0x0586,0x0181, 
+    0x0586,0x028c, 0x0588,0x0007, 0x058e,0x0033, 0x058e,0x008f, 0x058e,0x01d0, 
+    0x058e,0x027c, 0x0590,0x0003, 0x0596,0x0033, 0x0596,0x008f, 0x0596,0x0095, 
+    0x0596,0x01d0, 0x0596,0x027c, 0x05a2,0x026f, 0x05a5,0x0284, 0x05aa,0x017b, 
+    0x05ac,0x0205, 0x05b2,0x008f, 0x05b6,0x017b, 0x05b8,0x01da, 0x05c1,0x0276, 
+    0x05c6,0x0248, 0x05c8,0x0247, 0x05c8,0x027e, 0x05cc,0x003d, 0x05cc,0x01d4, 
+    0x05cc,0x01f3, 0x05d0,0x014e, 0x05d0,0x018d, 0x05da,0x00f9, 0x05dd,0x0006, 
+    0x05de,0x0044, 0x05e5,0x002e, 0x05e6,0x02f1, 0x05ea,0x01d4, 0x05ea,0x01f3, 
+    0x05ea,0x022d, 0x05ed,0x0002, 0x05f6,0x0027, 0x05fa,0x0097, 0x05fc,0x003d, 
+    0x0602,0x003d, 0x0606,0x00f3, 0x060a,0x0027, 0x060e,0x003d, 0x060e,0x0103, 
+    0x060e,0x018b, 0x060e,0x0231, 0x060e,0x02d1, 0x0611,0x01fc, 0x0611,0x0234, 
+    0x061a,0x0287, 0x061d,0x0214, 0x0621,0x01d4, 0x062a,0x0027, 0x062a,0x022d, 
+    0x062e,0x009e, 0x062e,0x0106, 0x062e,0x0198, 0x0632,0x009e, 0x0632,0x0106, 
+    0x0632,0x0198, 0x0639,0x0042, 0x0639,0x00b2, 0x0639,0x0108, 0x063d,0x01f8, 
+    0x0641,0x0086, 0x0641,0x009a, 0x0641,0x00ec, 0x0641,0x0172, 0x0645,0x0044, 
+    0x0649,0x0042, 0x0648,0x0087, 0x0648,0x00ed, 0x0648,0x0173, 0x0649,0x01a0, 
+    0x0648,0x0241, 0x0648,0x026f, 0x0648,0x02df, 0x0648,0x0307, 0x064c,0x023a, 
+    0x064c,0x02b3, 0x0651,0x0062, 0x0650,0x0217, 0x0651,0x02ac, 0x0650,0x02d6, 
+    0x0655,0x0042, 0x065d,0x0042, 0x0664,0x02b1, 0x0664,0x02ce, 0x0669,0x0238, 
+    0x066d,0x002a, 0x066c,0x0039, 0x066d,0x01f6, 0x066c,0x0213, 0x066c,0x022e, 
+    0x066d,0x02a2, 0x066c,0x02e1, 0x0671,0x002a, 0x0670,0x0030, 0x0670,0x0067, 
+    0x0670,0x00c9, 0x0670,0x01eb, 0x0670,0x01ef, 0x0670,0x02c3, 0x0675,0x0020, 
+    0x0678,0x0133, 0x0678,0x0148, 0x067c,0x0027, 0x0681,0x023a, 0x0684,0x0021, 
+    0x0684,0x00bf, 0x0684,0x00d0, 0x0689,0x01fc, 0x068e,0x0162, 0x068e,0x0183, 
+    0x0691,0x0200, 0x0696,0x0023, 0x0696,0x00e0, 0x0696,0x00fb, 0x0696,0x0268, 
+    0x069a,0x0282, 0x069d,0x007e, 0x06a2,0x004b, 0x06a2,0x023e, 0x06a2,0x02dc, 
+    0x06a6,0x0097, 0x06aa,0x02b1, 0x06aa,0x02ce, 0x06ae,0x0039, 0x06ae,0x0213, 
+    0x06ae,0x022e, 0x06ae,0x02e1, 0x06b2,0x0162, 0x06b2,0x0183, 0x06b6,0x0023, 
+    0x06b6,0x00e0, 0x06b6,0x00fb, 0x06ba,0x008f, 0x06ba,0x01e4, 0x06be,0x034b, 
+    0x06c1,0x0086, 0x06c1,0x009a, 0x06c1,0x00ec, 0x06c1,0x0172, 0x06c6,0x01da, 
+    0x06c6,0x0280, 0x06c6,0x0351, 0x06ce,0x008f, 0x06d2,0x01e3, 0x06d2,0x0287, 
+    0x06d2,0x0353, 0x06d6,0x027a, 0x06d6,0x029b, 0x06da,0x0033, 0x06da,0x01ce, 
+    0x06da,0x01f1, 0x06de,0x0133, 0x06de,0x0148, 0x06e2,0x0021, 0x06e2,0x00bf, 
+    0x06e2,0x00d0, 0x06e5,0x023a, 0x06e9,0x0004, 0x06ee,0x028c, 0x06ee,0x0338, 
+    0x06f2,0x0328, 0x06f2,0x0330, 0x06f4,0x0005, 0x06f9,0x01e0, 0x06fe,0x0328, 
+    0x06fe,0x0330, 0x0702,0x003d, 0x0702,0x00f3, 0x0702,0x0330, 0x0704,0x0003, 
+    0x070a,0x003d, 0x070a,0x00f3, 0x070a,0x01d4, 0x070a,0x01f3, 0x070a,0x0330, 
+    0x0711,0x032a, 0x0711,0x032e, 0x0716,0x003d, 0x0718,0x0205, 0x0718,0x0282, 
+    0x071e,0x00f3, 0x0720,0x01dc, 0x0720,0x02a5, 0x0726,0x0324, 0x072a,0x028a, 
+    0x072a,0x02a7, 0x0729,0x031c, 0x0729,0x032a, 0x072e,0x003d, 0x072e,0x00f9, 
+    0x072e,0x022d, 0x072e,0x0248, 0x072e,0x02e4, 0x0730,0x003d, 0x0730,0x0247, 
+    0x0730,0x02e3, 0x0730,0x0324, 0x0732,0x0324, 0x0739,0x032e, 0x073e,0x003d, 
+    0x0740,0x003d, 0x0744,0x027a, 0x0744,0x029b, 0x0748,0x0033, 0x0748,0x01ce, 
+    0x0748,0x01f1, 0x074c,0x0162, 0x074c,0x0183, 0x0750,0x0023, 0x0750,0x00e0, 
+    0x0750,0x00fb, 0x0755,0x0246, 0x075a,0x0095, 0x075a,0x0397, 0x075d,0x0004, 
+    0x076a,0x03b3, 0x076d,0x0002, 0x0772,0x02fb, 0x0772,0x0301, 0x0772,0x0315, 
+    0x0772,0x0397, 0x0776,0x008f, 0x077e,0x0027, 0x078a,0x00a1, 0x0792,0x009d, 
+    0x0792,0x00c3, 0x0792,0x02fb, 0x0792,0x0301, 0x0792,0x0315, 0x0792,0x03bd, 
+    0x0796,0x0027, 0x0796,0x024f, 0x079e,0x009d, 0x07a6,0x009d, 0x07a6,0x02fb, 
+    0x07a6,0x0301, 0x07a6,0x0315, 0x07a6,0x03bd, 0x07aa,0x0027, 0x07aa,0x024f, 
+    0x07ae,0x009d, 0x07b9,0x004e, 0x07b8,0x0087, 0x07b8,0x00ed, 0x07b8,0x0173, 
+    0x07b8,0x0197, 0x07b9,0x021a, 0x07b9,0x02b8, 0x07b9,0x0364, 0x07be,0x0029, 
+    0x07be,0x0030, 0x07c0,0x017b, 0x07c6,0x017b, 0x07c8,0x00f3, 0x07ce,0x00f3, 
+    0x07d0,0x008f, 0x07d6,0x008f, 0x07d9,0x01e8, 0x07dd,0x0292, 0x07e2,0x0053, 
+    0x07e6,0x008f, 0x07e6,0x00f3, 0x07e6,0x017b, 0x07e8,0x0029, 0x07e8,0x0030, 
+    0x07ec,0x0021, 0x07ec,0x02ad, 0x07f2,0x0181, 0x07f2,0x0315, 0x07f4,0x0021, 
+    0x07f8,0x020f, 0x07fd,0x002e, 0x0800,0x008f, 0x0805,0x0006, 0x0809,0x03c2, 
+    0x080d,0x0084, 0x0812,0x0009, 0x0811,0x0008, 0x0812,0x00f3, 0x0812,0x00f9, 
+    0x0812,0x017b, 0x0812,0x0181, 0x0814,0x0033, 0x0818,0x0023, 0x081c,0x0285, 
+    0x0826,0x03bd, 0x082c,0x008f, 0x082c,0x017b, 0x0832,0x0043, 0x0832,0x011b, 
+    0x0832,0x01b3, 0x0832,0x01c3, 0x0835,0x032a, 0x0838,0x0085, 0x0839,0x032a, 
+    0x083e,0x0049, 0x083d,0x0084, 0x083e,0x02fb, 0x083e,0x0301, 0x083e,0x0315, 
+    0x083e,0x0397, 0x0842,0x0009, 0x0841,0x0008, 0x0844,0x0009, 0x0846,0x008f, 
+    0x084a,0x0033, 0x084e,0x0285, 0x0851,0x009a, 0x0856,0x00a1, 0x0859,0x031c, 
+    0x085d,0x00b2, 0x0861,0x0012, 0x0861,0x02cc, 0x0865,0x0058, 0x0865,0x007e, 
+    0x0869,0x004a, 0x0871,0x0010, 0x0876,0x003d, 0x0879,0x032c, 0x087e,0x0089, 
+    0x0882,0x0229, 0x0882,0x022d, 0x0882,0x02c7, 0x0882,0x02cb, 0x0886,0x0021, 
+    0x0886,0x02ad, 0x0885,0x0356, 0x088a,0x0017, 0x088a,0x020f, 0x0889,0x0354, 
+    0x088d,0x009c, 0x0892,0x0089, 0x0895,0x0246, 0x089a,0x03bd, 0x089e,0x008f, 
+    0x089e,0x02f9, 0x089e,0x0313, 0x08a1,0x032a, 0x08a6,0x0053, 0x08a6,0x0095, 
+    0x08a6,0x0397, 0x08a8,0x017b, 0x08ad,0x031a, 0x08b2,0x017b, 0x08b4,0x00f3, 
+    0x08b5,0x02a0, 0x08b8,0x0089, 0x08c1,0x0024, 0x08c4,0x00f3, 0x08c9,0x007e, 
+    0x08cd,0x007c, 0x08cd,0x0222, 0x08cd,0x0294, 0x08d1,0x003a, 0x08d6,0x0009, 
+    0x08d9,0x003a, 0x08dc,0x001f, 0x08e0,0x008f, 0x08e0,0x017b, 0x08e4,0x0009, 
+    0x08e8,0x01ed, 0x08ed,0x031c, 0x08f2,0x003d, 0x08f6,0x008f, 0x08f6,0x017b, 
+    0x08fa,0x0009, 0x08fe,0x003d, 0x0902,0x01e9, 0x0904,0x01e9, 0x0904,0x0381, 
+    0x090a,0x03b1, 0x090d,0x031a, 0x0910,0x0299, 0x0914,0x034b, 0x0919,0x0008, 
+    0x091c,0x0033, 0x091c,0x003d, 0x0920,0x0027, 0x0924,0x0027, 0x0924,0x01fb, 
+    0x092a,0x01ce, 0x092a,0x01f1, 0x092d,0x031c, 0x0930,0x001f, 0x0936,0x00c5, 
+    0x0938,0x00c5, 0x0938,0x0381, 0x093c,0x001b, 0x0942,0x017d, 0x094a,0x0027, 
+    0x094e,0x0027, 0x094e,0x01fb, 0x0952,0x03b1, 0x095a,0x0029, 0x095a,0x0030, 
+    0x095d,0x0030, 0x0961,0x0030, 0x0966,0x02f9, 0x0966,0x0313, 0x0968,0x02eb, 
+    0x096d,0x0008, 0x0970,0x017b, 0x0974,0x0033, 0x0979,0x0150, 0x097d,0x009a, 
+    0x0982,0x0293, 0x0984,0x0293, 0x0984,0x0379, 0x098a,0x02eb, 0x098e,0x0009, 
+    0x0992,0x003d, 0x0996,0x003d, 0x0999,0x0062, 0x099e,0x003d, 0x09a0,0x0027, 
+    0x09a5,0x0144, 0x09a8,0x02b5, 0x09ae,0x008f, 0x09ae,0x009d, 0x09b2,0x004d, 
+    0x09b2,0x0053, 0x09b2,0x00c3, 0x09b2,0x013d, 0x09b2,0x01c5, 0x09b2,0x0271, 
+    0x09b4,0x0025, 0x09ba,0x0033, 0x09ba,0x0079, 0x09bc,0x0015, 0x09c2,0x013f, 
+    0x09c4,0x013f, 0x09c4,0x0379, 0x09ca,0x02b5, 0x09cd,0x0006, 0x09da,0x0009, 
+    0x09d9,0x0008, 0x09dc,0x000b, 0x09dc,0x004f, 0x09dd,0x0086, 0x09e0,0x0009, 
+    0x09e6,0x00a1, 0x09e8,0x0009, 0x09ed,0x0086, 0x09f2,0x001f, 0x09f2,0x002f, 
+    0x09f2,0x0049, 0x09f2,0x006f, 0x09f2,0x0085, 0x09f2,0x0091, 0x09f2,0x00a9, 
+    0x09f2,0x00d3, 0x09f2,0x00d7, 0x09f2,0x011d, 0x09f2,0x0121, 0x09f2,0x0235, 
+    0x09f2,0x0393, 0x09f6,0x0324, 0x09f8,0x0049, 0x09f8,0x00a9, 0x09f8,0x011d, 
+    0x09fe,0x001f, 0x09fe,0x0029, 0x09fe,0x0033, 0x09fe,0x003d, 0x09fe,0x0085, 
+    0x09fe,0x008f, 0x09fe,0x00d3, 0x0a00,0x003d, 0x0a06,0x012d, 0x0a0e,0x00b3, 
+    0x0a10,0x000b, 0x0a10,0x0387, 0x0a16,0x0059, 0x0a18,0x0009, 0x0a1e,0x0043, 
+    0x0a24,0x0085, 0x0a2a,0x0009, 0x0a2d,0x0008, 0x0a32,0x028a, 0x0a32,0x02a7, 
+    0x0a31,0x031c, 0x0a35,0x032e, 0x0a39,0x0006, 0x0a3a,0x0105, 0x0a3a,0x024f, 
+    0x0a3c,0x0299, 0x0a42,0x01ed, 0x0a46,0x0299, 0x0a48,0x01ed, 0x0a4c,0x0059, 
+    0x0a52,0x000b, 0x0a52,0x0387, 0x0a56,0x000b, 0x0a5e,0x0009, 0x0a60,0x003d, 
+    0x0a66,0x0105, 0x0a6a,0x0195, 0x0a6c,0x000b, 0x0a76,0x0053, 0x0a78,0x0009, 
+    0x0a7a,0x008f, 0x0a82,0x0299, 0x0a86,0x01ed, 0x0a8a,0x0027, 0x0a8e,0x004b, 
+    0x0a92,0x003d, 0x0a95,0x0322, 0x0a99,0x0038, 0x0a99,0x0090, 0x0a9c,0x0061, 
+    0x0a9c,0x00c7, 0x0a9c,0x012d, 0x0a9c,0x016f, 0x0a9c,0x017d, 0x0a9c,0x02c9, 
+    0x0a9c,0x0383, 0x0aa1,0x0010, 0x0aa4,0x00b3, 0x0aa8,0x002f, 0x0aac,0x0027, 
+    0x0ab0,0x004b, 0x0ab4,0x0043, 0x0ab9,0x0090, 0x0abd,0x0010, 0x0ac4,0x0019, 
+    0x0acc,0x00f5, 0x0acc,0x022b, 0x0acc,0x037b, 0x0ad2,0x008f, 0x0ad2,0x01f1, 
+    0x0ad6,0x0324, 0x0ad9,0x0330, 0x0ade,0x008f, 0x0ade,0x01f1, 0x0ae0,0x017b, 
+    0x0ae4,0x008f, 0x0ae9,0x004e, 0x0aee,0x0027, 0x0af2,0x028a, 0x0af2,0x02a7, 
+    0x0af1,0x031c, 0x0af6,0x0027, 0x0af9,0x031c, 0x0afe,0x00e9, 0x0afe,0x02bb, 
+    0x0b02,0x000b, 0x0b06,0x00f5, 0x0b06,0x022b, 0x0b06,0x037b, 0x0b0a,0x003d, 
+    0x0000,0x0000 
+};
+
+
diff --git a/src/opt/sim/module.make b/src/opt/sim/module.make
new file mode 100644
index 00000000..54058402
--- /dev/null
+++ b/src/opt/sim/module.make
@@ -0,0 +1,10 @@
+SRC +=  src/opt/sim/simMan.c \
+    src/opt/sim/simSat.c \
+    src/opt/sim/simSeq.c \
+    src/opt/sim/simSupp.c \
+    src/opt/sim/simSwitch.c \
+    src/opt/sim/simSym.c \
+    src/opt/sim/simSymSat.c \
+    src/opt/sim/simSymSim.c \
+    src/opt/sim/simSymStr.c \
+    src/opt/sim/simUtils.c
diff --git a/src/opt/sim/sim.h b/src/opt/sim/sim.h
new file mode 100644
index 00000000..7fcf5ae6
--- /dev/null
+++ b/src/opt/sim/sim.h
@@ -0,0 +1,233 @@
+/**CFile****************************************************************
+
+  FileName    [sim.h]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Simulation package.]
+
+  Synopsis    [External declarations.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: sim.h,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#ifndef __SIM_H__
+#define __SIM_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+    The ideas realized in this package are described in the paper:
+    "Detecting Symmetries in Boolean Functions using Circuit Representation, 
+    Simulation, and Satisfiability".
+*/
+
+////////////////////////////////////////////////////////////////////////
+///                          INCLUDES                                ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         PARAMETERS                               ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                         BASIC TYPES                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Sym_Man_t_ Sym_Man_t;
+struct Sym_Man_t_
+{
+    // info about the network
+    Abc_Ntk_t *       pNtk;          // the network 
+    Vec_Ptr_t *       vNodes;        // internal nodes in topological order
+    int               nInputs;
+    int               nOutputs;
+    // internal simulation information
+    int               nSimWords;     // the number of bits in simulation info
+    Vec_Ptr_t *       vSim;          // simulation info
+    // support information
+    Vec_Ptr_t *       vSuppFun;      // bit representation
+    Vec_Vec_t *       vSupports;     // integer representation
+    // symmetry info for each output
+    Vec_Ptr_t *       vMatrSymms;    // symmetric pairs
+    Vec_Ptr_t *       vMatrNonSymms; // non-symmetric pairs
+    Vec_Int_t *       vPairsTotal;   // total pairs
+    Vec_Int_t *       vPairsSym;     // symmetric pairs
+    Vec_Int_t *       vPairsNonSym;  // non-symmetric pairs
+    // temporary simulation info
+    unsigned *        uPatRand;
+    unsigned *        uPatCol;
+    unsigned *        uPatRow;
+    // temporary
+    Vec_Int_t *       vVarsU;
+    Vec_Int_t *       vVarsV;
+    int               iOutput;
+    int               iVar1;
+    int               iVar2;
+    int               iVar1Old;
+    int               iVar2Old;
+    // internal data structures
+    int               nSatRuns;
+    int               nSatRunsSat;
+    int               nSatRunsUnsat;
+    // pairs
+    int               nPairsSymm;
+    int               nPairsSymmStr;
+    int               nPairsNonSymm;
+    int               nPairsRem;
+    int               nPairsTotal;
+    // runtime statistics
+    int               timeStruct;
+    int               timeCount;
+    int               timeMatr;
+    int               timeSim;
+    int               timeFraig;
+    int               timeSat;
+    int               timeTotal;
+};
+
+typedef struct Sim_Man_t_ Sim_Man_t;
+struct Sim_Man_t_
+{
+    // info about the network
+    Abc_Ntk_t *       pNtk;
+    int               nInputs;
+    int               nOutputs;
+    int               fLightweight;
+    // internal simulation information
+    int               nSimBits;      // the number of bits in simulation info
+    int               nSimWords;     // the number of words in simulation info
+    Vec_Ptr_t *       vSim0;         // simulation info 1
+    Vec_Ptr_t *       vSim1;         // simulation info 2
+    // support information
+    int               nSuppBits;     // the number of bits in support info
+    int               nSuppWords;    // the number of words in support info
+    Vec_Ptr_t *       vSuppStr;      // structural supports
+    Vec_Ptr_t *       vSuppFun;      // functional supports
+    // simulation targets
+    Vec_Vec_t *       vSuppTargs;    // support targets
+    int               iInput;        // the input current processed
+    // internal data structures
+    Extra_MmFixed_t * pMmPat;   
+    Vec_Ptr_t *       vFifo;
+    Vec_Int_t *       vDiffs;
+    int               nSatRuns;
+    int               nSatRunsSat;
+    int               nSatRunsUnsat;
+    // runtime statistics
+    int               timeSim;
+    int               timeTrav;
+    int               timeFraig;
+    int               timeSat;
+    int               timeTotal;
+};
+
+typedef struct Sim_Pat_t_ Sim_Pat_t;
+struct Sim_Pat_t_
+{
+    int              Input;         // the input which it has detected
+    int              Output;        // the output for which it was collected
+    unsigned *       pData;         // the simulation data
+};
+
+////////////////////////////////////////////////////////////////////////
+///                      MACRO DEFINITIONS                           ///
+////////////////////////////////////////////////////////////////////////
+
+#define SIM_NUM_WORDS(n)      (((n)>>5) + (((n)&31) > 0))
+#define SIM_LAST_BITS(n)      ((((n)&31) > 0)? (n)&31 : 32)
+
+#define SIM_MASK_FULL         (0xFFFFFFFF)
+#define SIM_MASK_BEG(n)       (SIM_MASK_FULL >> (32-n))
+#define SIM_MASK_END(n)       (SIM_MASK_FULL << (n))
+#define SIM_SET_0_FROM(m,n)   ((m) & ~SIM_MASK_BEG(n))
+#define SIM_SET_1_FROM(m,n)   ((m) |  SIM_MASK_END(n))
+
+// generating random unsigned (#define RAND_MAX 0x7fff)
+#define SIM_RANDOM_UNSIGNED   ((((unsigned)rand()) << 24) ^ (((unsigned)rand()) << 12) ^ ((unsigned)rand()))
+
+// macros to get hold of bits in a bit string
+#define Sim_SetBit(p,i)       ((p)[(i)>>5] |= (1<<((i) & 31)))
+#define Sim_XorBit(p,i)       ((p)[(i)>>5] ^= (1<<((i) & 31)))
+#define Sim_HasBit(p,i)      (((p)[(i)>>5]  & (1<<((i) & 31))) > 0)
+
+// macros to get hold of the support info
+#define Sim_SuppStrSetVar(vSupps,pNode,v)     Sim_SetBit((unsigned*)(vSupps)->pArray[(pNode)->Id],(v))
+#define Sim_SuppStrHasVar(vSupps,pNode,v)     Sim_HasBit((unsigned*)(vSupps)->pArray[(pNode)->Id],(v))
+#define Sim_SuppFunSetVar(vSupps,Output,v)    Sim_SetBit((unsigned*)(vSupps)->pArray[Output],(v))
+#define Sim_SuppFunHasVar(vSupps,Output,v)    Sim_HasBit((unsigned*)(vSupps)->pArray[Output],(v))
+#define Sim_SimInfoSetVar(vSupps,pNode,v)     Sim_SetBit((unsigned*)(vSupps)->pArray[(pNode)->Id],(v))
+#define Sim_SimInfoHasVar(vSupps,pNode,v)     Sim_HasBit((unsigned*)(vSupps)->pArray[(pNode)->Id],(v))
+#define Sim_SimInfoGet(vInfo,pNode)           ((unsigned *)((vInfo)->pArray[(pNode)->Id]))
+
+////////////////////////////////////////////////////////////////////////
+///                    FUNCTION DECLARATIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/*=== simMan.c ==========================================================*/
+extern Sym_Man_t *     Sym_ManStart( Abc_Ntk_t * pNtk, int fVerbose );
+extern void            Sym_ManStop( Sym_Man_t * p );
+extern void            Sym_ManPrintStats( Sym_Man_t * p );
+extern Sim_Man_t *     Sim_ManStart( Abc_Ntk_t * pNtk, int fLightweight );
+extern void            Sim_ManStop( Sim_Man_t * p );
+extern void            Sim_ManPrintStats( Sim_Man_t * p );
+extern Sim_Pat_t *     Sim_ManPatAlloc( Sim_Man_t * p );
+extern void            Sim_ManPatFree( Sim_Man_t * p, Sim_Pat_t * pPat );
+/*=== simSeq.c ==========================================================*/
+extern Vec_Ptr_t *     Sim_SimulateSeqRandom( Abc_Ntk_t * pNtk, int nFrames, int nWords );
+extern Vec_Ptr_t *     Sim_SimulateSeqModel( Abc_Ntk_t * pNtk, int nFrames, int * pModel );
+/*=== simSupp.c ==========================================================*/
+extern Vec_Ptr_t *     Sim_ComputeStrSupp( Abc_Ntk_t * pNtk );
+extern Vec_Ptr_t *     Sim_ComputeFunSupp( Abc_Ntk_t * pNtk, int fVerbose );
+/*=== simSym.c ==========================================================*/
+extern int             Sim_ComputeTwoVarSymms( Abc_Ntk_t * pNtk, int fVerbose );
+/*=== simSymSat.c ==========================================================*/
+extern int             Sim_SymmsGetPatternUsingSat( Sym_Man_t * p, unsigned * pPattern );
+/*=== simSymStr.c ==========================================================*/
+extern void            Sim_SymmsStructCompute( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMatrs, Vec_Ptr_t * vSuppFun );
+/*=== simSymSim.c ==========================================================*/
+extern void            Sim_SymmsSimulate( Sym_Man_t * p, unsigned * pPatRand, Vec_Ptr_t * vMatrsNonSym );
+/*=== simUtil.c ==========================================================*/
+extern Vec_Ptr_t *     Sim_UtilInfoAlloc( int nSize, int nWords, bool fClean );
+extern void            Sim_UtilInfoFree( Vec_Ptr_t * p );
+extern void            Sim_UtilInfoAdd( unsigned * pInfo1, unsigned * pInfo2, int nWords );
+extern void            Sim_UtilInfoDetectDiffs( unsigned * pInfo1, unsigned * pInfo2, int nWords, Vec_Int_t * vDiffs );
+extern void            Sim_UtilInfoDetectNews( unsigned * pInfo1, unsigned * pInfo2, int nWords, Vec_Int_t * vDiffs );
+extern void            Sim_UtilInfoFlip( Sim_Man_t * p, Abc_Obj_t * pNode );
+extern bool            Sim_UtilInfoCompare( Sim_Man_t * p, Abc_Obj_t * pNode );
+extern void            Sim_UtilSimulate( Sim_Man_t * p, bool fFirst );
+extern void            Sim_UtilSimulateNode( Sim_Man_t * p, Abc_Obj_t * pNode, bool fType, bool fType1, bool fType2 );
+extern void            Sim_UtilSimulateNodeOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords, int nOffset );
+extern void            Sim_UtilTransferNodeOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords, int nOffset, int fShift );
+extern int             Sim_UtilCountSuppSizes( Sim_Man_t * p, int fStruct );
+extern int             Sim_UtilCountOnes( unsigned * pSimInfo, int nSimWords );
+extern Vec_Int_t *     Sim_UtilCountOnesArray( Vec_Ptr_t * vInfo, int nSimWords );
+extern void            Sim_UtilSetRandom( unsigned * pPatRand, int nSimWords );
+extern void            Sim_UtilSetCompl( unsigned * pPatRand, int nSimWords );
+extern void            Sim_UtilSetConst( unsigned * pPatRand, int nSimWords, int fConst1 );
+extern int             Sim_UtilInfoIsEqual( unsigned * pPats1, unsigned * pPats2, int nSimWords );
+extern int             Sim_UtilInfoIsImp( unsigned * pPats1, unsigned * pPats2, int nSimWords );
+extern int             Sim_UtilInfoIsClause( unsigned * pPats1, unsigned * pPats2, int nSimWords );
+extern int             Sim_UtilCountAllPairs( Vec_Ptr_t * vSuppFun, int nSimWords, Vec_Int_t * vCounters );
+extern void            Sim_UtilCountPairsAll( Sym_Man_t * p );
+extern int             Sim_UtilMatrsAreDisjoint( Sym_Man_t * p );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
diff --git a/src/opt/sim/simMan.c b/src/opt/sim/simMan.c
new file mode 100644
index 00000000..3b50ad84
--- /dev/null
+++ b/src/opt/sim/simMan.c
@@ -0,0 +1,288 @@
+/**CFile****************************************************************
+
+  FileName    [simMan.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Simulation manager.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simMan.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the simulation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Sym_Man_t * Sym_ManStart( Abc_Ntk_t * pNtk, int fVerbose )
+{
+    Sym_Man_t * p;
+    int i, v; 
+    // start the manager
+    p = ALLOC( Sym_Man_t, 1 );
+    memset( p, 0, sizeof(Sym_Man_t) );
+    p->pNtk = pNtk;
+    p->vNodes     = Abc_NtkDfs( pNtk, 0 );
+    p->nInputs    = Abc_NtkCiNum(p->pNtk);
+    p->nOutputs   = Abc_NtkCoNum(p->pNtk);
+    // internal simulation information
+    p->nSimWords  = SIM_NUM_WORDS(p->nInputs);
+    p->vSim       = Sim_UtilInfoAlloc( Abc_NtkObjNumMax(pNtk), p->nSimWords, 0 );
+    // symmetry info for each output
+    p->vMatrSymms    = Vec_PtrStart( p->nOutputs );
+    p->vMatrNonSymms = Vec_PtrStart( p->nOutputs );
+    p->vPairsTotal   = Vec_IntStart( p->nOutputs );
+    p->vPairsSym     = Vec_IntStart( p->nOutputs );
+    p->vPairsNonSym  = Vec_IntStart( p->nOutputs );
+    for ( i = 0; i < p->nOutputs; i++ )
+    {
+        p->vMatrSymms->pArray[i]    = Extra_BitMatrixStart( p->nInputs );
+        p->vMatrNonSymms->pArray[i] = Extra_BitMatrixStart( p->nInputs );
+    }
+    // temporary patterns
+    p->uPatRand = ALLOC( unsigned, p->nSimWords );
+    p->uPatCol  = ALLOC( unsigned, p->nSimWords );
+    p->uPatRow  = ALLOC( unsigned, p->nSimWords );
+    p->vVarsU   = Vec_IntStart( 100 );
+    p->vVarsV   = Vec_IntStart( 100 );
+    // compute supports
+    p->vSuppFun  = Sim_ComputeFunSupp( pNtk, fVerbose );
+    p->vSupports = Vec_VecStart( p->nOutputs );
+    for ( i = 0; i < p->nOutputs; i++ )
+        for ( v = 0; v < p->nInputs; v++ )
+            if ( Sim_SuppFunHasVar( p->vSuppFun, i, v ) )
+                Vec_VecPush( p->vSupports, i, (void *)v );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the simulation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sym_ManStop( Sym_Man_t * p )
+{
+    int i;
+    Sym_ManPrintStats( p );
+    if ( p->vSuppFun )     Sim_UtilInfoFree( p->vSuppFun );   
+    if ( p->vSim )         Sim_UtilInfoFree( p->vSim );   
+    if ( p->vNodes )       Vec_PtrFree( p->vNodes );
+    if ( p->vSupports )    Vec_VecFree( p->vSupports );
+    for ( i = 0; i < p->nOutputs; i++ )
+    {
+        Extra_BitMatrixStop( p->vMatrSymms->pArray[i] );
+        Extra_BitMatrixStop( p->vMatrNonSymms->pArray[i] );
+    }
+    Vec_IntFree( p->vVarsU );
+    Vec_IntFree( p->vVarsV );
+    Vec_PtrFree( p->vMatrSymms );
+    Vec_PtrFree( p->vMatrNonSymms );
+    Vec_IntFree( p->vPairsTotal );
+    Vec_IntFree( p->vPairsSym );
+    Vec_IntFree( p->vPairsNonSym );
+    FREE( p->uPatRand );
+    FREE( p->uPatCol );
+    FREE( p->uPatRow );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the manager statisticis.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sym_ManPrintStats( Sym_Man_t * p )
+{
+//    printf( "Inputs = %5d. Outputs = %5d. Sim words = %5d.\n", 
+//        Abc_NtkCiNum(p->pNtk), Abc_NtkCoNum(p->pNtk), p->nSimWords );
+    printf( "Total symm         = %8d.\n", p->nPairsSymm );
+    printf( "Structural symm    = %8d.\n", p->nPairsSymmStr );
+    printf( "Total non-sym      = %8d.\n", p->nPairsNonSymm );
+    printf( "Total var pairs    = %8d.\n", p->nPairsTotal );
+    printf( "Sat runs SAT       = %8d.\n", p->nSatRunsSat );
+    printf( "Sat runs UNSAT     = %8d.\n", p->nSatRunsUnsat );
+    PRT( "Structural  ", p->timeStruct );
+    PRT( "Simulation  ", p->timeSim );
+    PRT( "Matrix      ", p->timeMatr );
+    PRT( "Counting    ", p->timeCount );
+    PRT( "Fraiging    ", p->timeFraig );
+    PRT( "SAT         ", p->timeSat );
+    PRT( "TOTAL       ", p->timeTotal );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the simulation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Sim_Man_t * Sim_ManStart( Abc_Ntk_t * pNtk, int fLightweight )
+{
+    Sim_Man_t * p;
+    // start the manager
+    p = ALLOC( Sim_Man_t, 1 );
+    memset( p, 0, sizeof(Sim_Man_t) );
+    p->pNtk = pNtk;
+    p->nInputs    = Abc_NtkCiNum(p->pNtk);
+    p->nOutputs   = Abc_NtkCoNum(p->pNtk);
+    // internal simulation information
+    p->nSimBits   = 2048;
+    p->nSimWords  = SIM_NUM_WORDS(p->nSimBits);
+    p->vSim0      = Sim_UtilInfoAlloc( Abc_NtkObjNumMax(pNtk), p->nSimWords, 0 );
+    p->fLightweight = fLightweight;
+    if (!p->fLightweight) {
+        p->vSim1      = Sim_UtilInfoAlloc( Abc_NtkObjNumMax(pNtk), p->nSimWords, 0 );
+        // support information
+        p->nSuppBits  = Abc_NtkCiNum(pNtk);
+        p->nSuppWords = SIM_NUM_WORDS(p->nSuppBits);
+        p->vSuppStr   = Sim_ComputeStrSupp( pNtk );
+        p->vSuppFun   = Sim_UtilInfoAlloc( Abc_NtkCoNum(p->pNtk),  p->nSuppWords, 1 );
+        // other data
+        p->pMmPat     = Extra_MmFixedStart( sizeof(Sim_Pat_t) + p->nSuppWords * sizeof(unsigned) ); 
+        p->vFifo      = Vec_PtrAlloc( 100 );
+        p->vDiffs     = Vec_IntAlloc( 100 );
+        // allocate support targets (array of unresolved outputs for each input)
+        p->vSuppTargs = Vec_VecStart( p->nInputs );
+    }
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Stops the simulation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_ManStop( Sim_Man_t * p )
+{
+    Sim_ManPrintStats( p );
+    if ( p->vSim0 )        Sim_UtilInfoFree( p->vSim0 );       
+    if ( p->vSim1 )        Sim_UtilInfoFree( p->vSim1 );       
+    if ( p->vSuppStr )     Sim_UtilInfoFree( p->vSuppStr );    
+//    if ( p->vSuppFun )     Sim_UtilInfoFree( p->vSuppFun );    
+    if ( p->vSuppTargs )   Vec_VecFree( p->vSuppTargs );
+    if ( p->pMmPat )       Extra_MmFixedStop( p->pMmPat );
+    if ( p->vFifo )        Vec_PtrFree( p->vFifo );
+    if ( p->vDiffs )       Vec_IntFree( p->vDiffs );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the manager statisticis.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_ManPrintStats( Sim_Man_t * p )
+{
+//    printf( "Inputs = %5d. Outputs = %5d. Sim words = %5d.\n", 
+//        Abc_NtkCiNum(p->pNtk), Abc_NtkCoNum(p->pNtk), p->nSimWords );
+    printf( "Total func supps   = %8d.\n", Sim_UtilCountSuppSizes(p, 0) );
+    printf( "Total struct supps = %8d.\n", Sim_UtilCountSuppSizes(p, 1) );
+    printf( "Sat runs SAT       = %8d.\n", p->nSatRunsSat );
+    printf( "Sat runs UNSAT     = %8d.\n", p->nSatRunsUnsat );
+    PRT( "Simulation  ", p->timeSim );
+    PRT( "Traversal   ", p->timeTrav );
+    PRT( "Fraiging    ", p->timeFraig );
+    PRT( "SAT         ", p->timeSat );
+    PRT( "TOTAL       ", p->timeTotal );
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns one simulation pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Sim_Pat_t * Sim_ManPatAlloc( Sim_Man_t * p )
+{
+    Sim_Pat_t * pPat;
+    pPat = (Sim_Pat_t *)Extra_MmFixedEntryFetch( p->pMmPat );
+    pPat->Output = -1;
+    pPat->pData  = (unsigned *)((char *)pPat + sizeof(Sim_Pat_t));
+    memset( pPat->pData, 0, p->nSuppWords * sizeof(unsigned) );
+    return pPat;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns one simulation pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_ManPatFree( Sim_Man_t * p, Sim_Pat_t * pPat )
+{
+    Extra_MmFixedEntryRecycle( p->pMmPat, (char *)pPat );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSat.c b/src/opt/sim/simSat.c
new file mode 100644
index 00000000..d514f7f2
--- /dev/null
+++ b/src/opt/sim/simSat.c
@@ -0,0 +1,48 @@
+/**CFile****************************************************************
+
+  FileName    [simSat.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Simulation to determine functional support.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simSat.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+ 
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSeq.c b/src/opt/sim/simSeq.c
new file mode 100644
index 00000000..49fb939f
--- /dev/null
+++ b/src/opt/sim/simSeq.c
@@ -0,0 +1,171 @@
+/**CFile****************************************************************
+
+  FileName    [simSeq.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Simulation for sequential circuits.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simUtils.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Sim_SimulateSeqFrame( Vec_Ptr_t * vInfo, Abc_Ntk_t * pNtk, int iFrames, int nWords, int fTransfer );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates sequential circuit.]
+
+  Description [Takes sequential circuit (pNtk). Simulates the given number
+  (nFrames) of the circuit with the given number of machine words (nWords)
+  of random simulation data, starting from the initial state. If the initial
+  state of some latches is a don't-care, uses random input for that latch.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Sim_SimulateSeqRandom( Abc_Ntk_t * pNtk, int nFrames, int nWords )
+{
+    Vec_Ptr_t * vInfo;
+    Abc_Obj_t * pNode;
+    int i;
+    assert( Abc_NtkIsStrash(pNtk) );
+    vInfo = Sim_UtilInfoAlloc( Abc_NtkObjNumMax(pNtk), nWords * nFrames, 0 );
+    // set the constant data
+    pNode = Abc_AigConst1(pNtk);
+    Sim_UtilSetConst( Sim_SimInfoGet(vInfo,pNode), nWords * nFrames, 1 );
+    // set the random PI data
+    Abc_NtkForEachPi( pNtk, pNode, i )
+        Sim_UtilSetRandom( Sim_SimInfoGet(vInfo,pNode), nWords * nFrames );
+    // set the initial state data
+    Abc_NtkForEachLatch( pNtk, pNode, i )
+        if ( Abc_LatchIsInit0(pNode) )
+            Sim_UtilSetConst( Sim_SimInfoGet(vInfo,pNode), nWords, 0 );
+        else if ( Abc_LatchIsInit1(pNode) )
+            Sim_UtilSetConst( Sim_SimInfoGet(vInfo,pNode), nWords, 1 );
+        else 
+            Sim_UtilSetRandom( Sim_SimInfoGet(vInfo,pNode), nWords );
+    // simulate the nodes for the given number of timeframes
+    for ( i = 0; i < nFrames; i++ )
+        Sim_SimulateSeqFrame( vInfo, pNtk, i, nWords, (int)(i < nFrames-1) );
+    return vInfo;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates sequential circuit.]
+
+  Description [Takes sequential circuit (pNtk). Simulates the given number
+  (nFrames) of the circuit with the given model. The model is assumed to 
+  contain values of PIs for each frame. The latches are initialized to
+  the initial state. One word of data is simulated.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Sim_SimulateSeqModel( Abc_Ntk_t * pNtk, int nFrames, int * pModel )
+{
+    Vec_Ptr_t * vInfo;
+    Abc_Obj_t * pNode;
+    unsigned * pUnsigned;
+    int i, k;
+    vInfo = Sim_UtilInfoAlloc( Abc_NtkObjNumMax(pNtk), nFrames, 0 );
+    // set the constant data
+    pNode = Abc_AigConst1(pNtk);
+    Sim_UtilSetConst( Sim_SimInfoGet(vInfo,pNode), nFrames, 1 );
+    // set the random PI data
+    Abc_NtkForEachPi( pNtk, pNode, i )
+    {
+        pUnsigned = Sim_SimInfoGet(vInfo,pNode);
+        for ( k = 0; k < nFrames; k++ )
+            pUnsigned[k] = pModel[k * Abc_NtkPiNum(pNtk) + i] ? ~((unsigned)0) : 0;
+    }
+    // set the initial state data
+    Abc_NtkForEachLatch( pNtk, pNode, i )
+    {
+        pUnsigned = Sim_SimInfoGet(vInfo,pNode);
+        if ( Abc_LatchIsInit0(pNode) )
+            pUnsigned[0] = 0;
+        else if ( Abc_LatchIsInit1(pNode) )
+            pUnsigned[0] = ~((unsigned)0);
+        else 
+            pUnsigned[0] = SIM_RANDOM_UNSIGNED;
+    }
+    // simulate the nodes for the given number of timeframes
+    for ( i = 0; i < nFrames; i++ )
+        Sim_SimulateSeqFrame( vInfo, pNtk, i, 1, (int)(i < nFrames-1) );
+/*
+    // print the simulated values
+    for ( i = 0; i < nFrames; i++ )
+    {
+        printf( "Frame %d : ", i+1 );
+        Abc_NtkForEachPi( pNtk, pNode, k )
+            printf( "%d", Sim_SimInfoGet(vInfo,pNode)[i] > 0 );
+        printf( " " );
+        Abc_NtkForEachLatch( pNtk, pNode, k )
+            printf( "%d", Sim_SimInfoGet(vInfo,pNode)[i] > 0 );
+        printf( " " );
+        Abc_NtkForEachPo( pNtk, pNode, k )
+            printf( "%d", Sim_SimInfoGet(vInfo,pNode)[i] > 0 );
+        printf( "\n" );
+    }
+    printf( "\n" );
+*/
+    return vInfo;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one frame of sequential circuit.]
+
+  Description [Assumes that the latches and POs are already initialized.
+  In the end transfers the data to the latches of the next frame.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SimulateSeqFrame( Vec_Ptr_t * vInfo, Abc_Ntk_t * pNtk, int iFrames, int nWords, int fTransfer )
+{
+    Abc_Obj_t * pNode;
+    int i;
+    Abc_NtkForEachNode( pNtk, pNode, i )
+        Sim_UtilSimulateNodeOne( pNode, vInfo, nWords, iFrames * nWords );
+    Abc_NtkForEachPo( pNtk, pNode, i )
+        Sim_UtilTransferNodeOne( pNode, vInfo, nWords, iFrames * nWords, 0 );
+    if ( !fTransfer )
+        return;
+    Abc_NtkForEachLatch( pNtk, pNode, i )
+        Sim_UtilTransferNodeOne( pNode, vInfo, nWords, iFrames * nWords, 1 );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSupp.c b/src/opt/sim/simSupp.c
new file mode 100644
index 00000000..f7048f4a
--- /dev/null
+++ b/src/opt/sim/simSupp.c
@@ -0,0 +1,597 @@
+/**CFile****************************************************************
+
+  FileName    [simSupp.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Simulation to determine functional support.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simSupp.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "fraig.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+ 
+static int    Sim_ComputeSuppRound( Sim_Man_t * p, bool fUseTargets );
+static int    Sim_ComputeSuppRoundNode( Sim_Man_t * p, int iNumCi, bool fUseTargets );
+static void   Sim_ComputeSuppSetTargets( Sim_Man_t * p );
+
+static void   Sim_UtilAssignRandom( Sim_Man_t * p );
+static void   Sim_UtilAssignFromFifo( Sim_Man_t * p );
+static void   Sim_SolveTargetsUsingSat( Sim_Man_t * p, int nCounters );
+static int    Sim_SolveSuppModelVerify( Abc_Ntk_t * pNtk, int * pModel, int Input, int Output );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes structural supports.]
+
+  Description [Supports are returned as an array of bit strings, one
+  for each CO.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Sim_ComputeStrSupp( Abc_Ntk_t * pNtk )
+{
+    Vec_Ptr_t * vSuppStr;
+    Abc_Obj_t * pNode;
+    unsigned * pSimmNode, * pSimmNode1, * pSimmNode2;
+    int nSuppWords, i, k;
+    // allocate room for structural supports
+    nSuppWords = SIM_NUM_WORDS( Abc_NtkCiNum(pNtk) );
+    vSuppStr   = Sim_UtilInfoAlloc( Abc_NtkObjNumMax(pNtk), nSuppWords, 1 );
+    // assign the structural support to the PIs
+    Abc_NtkForEachCi( pNtk, pNode, i )
+        Sim_SuppStrSetVar( vSuppStr, pNode, i );
+    // derive the structural supports of the internal nodes
+    Abc_NtkForEachNode( pNtk, pNode, i )
+    {
+//        if ( Abc_NodeIsConst(pNode) )
+//            continue;
+        pSimmNode  = vSuppStr->pArray[ pNode->Id ];
+        pSimmNode1 = vSuppStr->pArray[ Abc_ObjFaninId0(pNode) ];
+        pSimmNode2 = vSuppStr->pArray[ Abc_ObjFaninId1(pNode) ];
+        for ( k = 0; k < nSuppWords; k++ )
+            pSimmNode[k] = pSimmNode1[k] | pSimmNode2[k];
+    }
+    // set the structural supports of the PO nodes
+    Abc_NtkForEachCo( pNtk, pNode, i )
+    {
+        pSimmNode  = vSuppStr->pArray[ pNode->Id ];
+        pSimmNode1 = vSuppStr->pArray[ Abc_ObjFaninId0(pNode) ];
+        for ( k = 0; k < nSuppWords; k++ )
+            pSimmNode[k] = pSimmNode1[k];
+    }
+    return vSuppStr;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Compute functional supports.]
+
+  Description [Supports are returned as an array of bit strings, one
+  for each CO.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Sim_ComputeFunSupp( Abc_Ntk_t * pNtk, int fVerbose )
+{
+    Sim_Man_t * p;
+    Vec_Ptr_t * vResult;
+    int nSolved, i, clk = clock();
+
+    srand( 0xABC );
+
+    // start the simulation manager
+    p = Sim_ManStart( pNtk, 0 );
+
+    // compute functional support using one round of random simulation
+    Sim_UtilAssignRandom( p );
+    Sim_ComputeSuppRound( p, 0 );
+
+    // set the support targets 
+    Sim_ComputeSuppSetTargets( p );
+if ( fVerbose )
+    printf( "Number of support targets after simulation = %5d.\n", Vec_VecSizeSize(p->vSuppTargs) );
+    if ( Vec_VecSizeSize(p->vSuppTargs) == 0 )
+        goto exit;
+
+    for ( i = 0; i < 1; i++ )
+    {
+        // compute patterns using one round of random simulation
+        Sim_UtilAssignRandom( p );
+        nSolved = Sim_ComputeSuppRound( p, 1 );
+        if ( Vec_VecSizeSize(p->vSuppTargs) == 0 )
+            goto exit;
+
+if ( fVerbose )
+    printf( "Targets = %5d.   Solved = %5d.  Fifo = %5d.\n", 
+       Vec_VecSizeSize(p->vSuppTargs), nSolved, Vec_PtrSize(p->vFifo) );
+    }
+
+    // try to solve the support targets
+    while ( Vec_VecSizeSize(p->vSuppTargs) > 0 )
+    {
+        // solve targets until the first disproved one (which gives counter-example)
+        Sim_SolveTargetsUsingSat( p, p->nSimWords/p->nSuppWords );
+        // compute additional functional support
+        Sim_UtilAssignFromFifo( p );
+        nSolved = Sim_ComputeSuppRound( p, 1 );
+
+if ( fVerbose )
+    printf( "Targets = %5d.   Solved = %5d.  Fifo = %5d.  SAT runs = %3d.\n", 
+            Vec_VecSizeSize(p->vSuppTargs), nSolved, Vec_PtrSize(p->vFifo), p->nSatRuns );
+    }
+
+exit:
+p->timeTotal = clock() - clk;
+    vResult = p->vSuppFun;  
+    //  p->vSuppFun = NULL;
+    Sim_ManStop( p );
+    return vResult;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes functional support using one round of simulation.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_ComputeSuppRound( Sim_Man_t * p, bool fUseTargets )
+{
+    Vec_Int_t * vTargets;
+    int i, Counter = 0;
+    int clk;
+    // perform one round of random simulation
+clk = clock();
+    Sim_UtilSimulate( p, 0 );
+p->timeSim += clock() - clk;
+    // iterate through the CIs and detect COs that depend on them
+    for ( i = p->iInput; i < p->nInputs; i++ )
+    {
+        vTargets = p->vSuppTargs->pArray[i];
+        if ( fUseTargets && vTargets->nSize == 0 )
+            continue;
+        Counter += Sim_ComputeSuppRoundNode( p, i, fUseTargets );
+    }
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes functional support for one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_ComputeSuppRoundNode( Sim_Man_t * p, int iNumCi, bool fUseTargets )
+{
+    int fVerbose = 0;
+    Sim_Pat_t * pPat;
+    Vec_Int_t * vTargets;
+    Vec_Vec_t * vNodesByLevel;
+    Abc_Obj_t * pNodeCi, * pNode;
+    int i, k, v, Output, LuckyPat, fType0, fType1;
+    int Counter = 0;
+    int fFirst = 1;
+    int clk;
+    // collect nodes by level in the TFO of the CI 
+    // this proceduredoes not collect the CIs and COs
+    // but it increments TravId of the collected nodes and CIs/COs
+clk = clock();
+    pNodeCi       = Abc_NtkCi( p->pNtk, iNumCi );
+    vNodesByLevel = Abc_DfsLevelized( pNodeCi, 0 );
+p->timeTrav += clock() - clk;
+    // complement the simulation info of the selected CI
+    Sim_UtilInfoFlip( p, pNodeCi );
+    // simulate the levelized structure of nodes
+    Vec_VecForEachEntry( vNodesByLevel, pNode, i, k )
+    {
+        fType0 = Abc_NodeIsTravIdCurrent( Abc_ObjFanin0(pNode) );
+        fType1 = Abc_NodeIsTravIdCurrent( Abc_ObjFanin1(pNode) );
+clk = clock();
+        Sim_UtilSimulateNode( p, pNode, 1, fType0, fType1 );
+p->timeSim += clock() - clk;
+    }
+    // set the simulation info of the affected COs
+    if ( fUseTargets )
+    {
+        vTargets = p->vSuppTargs->pArray[iNumCi];
+        for ( i = vTargets->nSize - 1; i >= 0; i-- )
+        {
+            // get the target output
+            Output = vTargets->pArray[i];
+            // get the target node
+            pNode  = Abc_ObjFanin0( Abc_NtkCo(p->pNtk, Output) );
+            // the output should be in the cone
+            assert( Abc_NodeIsTravIdCurrent(pNode) );
+
+            // skip if the simulation info is equal
+            if ( Sim_UtilInfoCompare( p, pNode ) )
+                continue;
+
+            // otherwise, we solved a new target
+            Vec_IntRemove( vTargets, Output );
+if ( fVerbose )
+    printf( "(%d,%d) ", iNumCi, Output );
+            Counter++;
+            // make sure this variable is not yet detected
+            assert( !Sim_SuppFunHasVar(p->vSuppFun, Output, iNumCi) );
+            // set this variable
+            Sim_SuppFunSetVar( p->vSuppFun, Output, iNumCi );
+            
+            // detect the differences in the simulation info
+            Sim_UtilInfoDetectDiffs( p->vSim0->pArray[pNode->Id], p->vSim1->pArray[pNode->Id], p->nSimWords, p->vDiffs );
+            // create new patterns
+            if ( !fFirst && p->vFifo->nSize > 1000 )
+                continue;
+
+            Vec_IntForEachEntry( p->vDiffs, LuckyPat, k )
+            {
+                // set the new pattern
+                pPat = Sim_ManPatAlloc( p );
+                pPat->Input  = iNumCi;
+                pPat->Output = Output;
+                Abc_NtkForEachCi( p->pNtk, pNodeCi, v )
+                    if ( Sim_SimInfoHasVar( p->vSim0, pNodeCi, LuckyPat ) )
+                        Sim_SetBit( pPat->pData, v );
+                Vec_PtrPush( p->vFifo, pPat );
+
+                fFirst = 0;
+                break;
+            }
+        }
+if ( fVerbose && Counter )
+printf( "\n" );
+    }
+    else
+    {
+        Abc_NtkForEachCo( p->pNtk, pNode, Output )
+        {
+            if ( !Abc_NodeIsTravIdCurrent( pNode ) )
+                continue;
+            if ( !Sim_UtilInfoCompare( p, Abc_ObjFanin0(pNode) ) )
+            {
+                if ( !Sim_SuppFunHasVar(p->vSuppFun, Output, iNumCi) )
+                {
+                    Counter++;
+                    Sim_SuppFunSetVar( p->vSuppFun, Output, iNumCi );
+                }
+            }
+        }
+    }
+    Vec_VecFree( vNodesByLevel );
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the simulation targets.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_ComputeSuppSetTargets( Sim_Man_t * p )
+{
+    Abc_Obj_t * pNode;
+    unsigned * pSuppStr, * pSuppFun;
+    int i, k, Num;
+    Abc_NtkForEachCo( p->pNtk, pNode, i )
+    {
+        pSuppStr = p->vSuppStr->pArray[pNode->Id];
+        pSuppFun = p->vSuppFun->pArray[i];
+        // find vars in the structural support that are not in the functional support
+        Sim_UtilInfoDetectNews( pSuppFun, pSuppStr, p->nSuppWords, p->vDiffs );
+        Vec_IntForEachEntry( p->vDiffs, Num, k )
+            Vec_VecPush( p->vSuppTargs, Num, (void *)i );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns random simulation info to the PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilAssignRandom( Sim_Man_t * p )
+{
+    Abc_Obj_t * pNode;
+    unsigned * pSimInfo;
+    int i, k;
+    // assign the random/systematic simulation info to the PIs
+    Abc_NtkForEachCi( p->pNtk, pNode, i )
+    {
+        pSimInfo = p->vSim0->pArray[pNode->Id];
+        for ( k = 0; k < p->nSimWords; k++ )
+            pSimInfo[k] = SIM_RANDOM_UNSIGNED;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Sets the new patterns from fifo.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilAssignFromFifo( Sim_Man_t * p )
+{
+    int fUseOneWord = 0;
+    Abc_Obj_t * pNode;
+    Sim_Pat_t * pPat;
+    unsigned * pSimInfo;
+    int nWordsNew, iWord, iWordLim, i, w;
+    int iBeg, iEnd;
+    int Counter = 0;
+    // go through the patterns and fill in the dist-1 minterms for each
+    for ( iWord = 0; p->vFifo->nSize > 0; iWord = iWordLim )
+    {
+        ++Counter;
+        // get the pattern
+        pPat = Vec_PtrPop( p->vFifo );
+        if ( fUseOneWord )
+        {
+            // get the first word of the next series
+            iWordLim = iWord + 1; 
+            // set the pattern for all PIs from iBit to iWord + p->nInputs
+            iBeg = p->iInput;
+            iEnd = ABC_MIN( iBeg + 32, p->nInputs );
+//            for ( i = iBeg; i < iEnd; i++ )
+            Abc_NtkForEachCi( p->pNtk, pNode, i )
+            {
+                pNode = Abc_NtkCi(p->pNtk,i);
+                pSimInfo = p->vSim0->pArray[pNode->Id];
+                if ( Sim_HasBit(pPat->pData, i) )
+                    pSimInfo[iWord] = SIM_MASK_FULL;
+                else
+                    pSimInfo[iWord] = 0;
+                // flip one bit
+                if ( i >= iBeg && i < iEnd )
+                    Sim_XorBit( pSimInfo + iWord, i-iBeg );
+            }
+        }
+        else
+        {
+            // get the number of words for the remaining inputs
+            nWordsNew = p->nSuppWords;
+//            nWordsNew = SIM_NUM_WORDS( p->nInputs - p->iInput );
+            // get the first word of the next series
+            iWordLim = (iWord + nWordsNew < p->nSimWords)? iWord + nWordsNew : p->nSimWords; 
+            // set the pattern for all CIs from iWord to iWord + nWordsNew
+            Abc_NtkForEachCi( p->pNtk, pNode, i )
+            {
+                pSimInfo = p->vSim0->pArray[pNode->Id];
+                if ( Sim_HasBit(pPat->pData, i) )
+                {
+                    for ( w = iWord; w < iWordLim; w++ )
+                        pSimInfo[w] = SIM_MASK_FULL;
+                }
+                else
+                {
+                    for ( w = iWord; w < iWordLim; w++ )
+                        pSimInfo[w] = 0;
+                }
+                Sim_XorBit( pSimInfo + iWord, i );
+                // flip one bit
+//                if ( i >= p->iInput )
+//                    Sim_XorBit( pSimInfo + iWord, i-p->iInput );
+            }
+        }
+        Sim_ManPatFree( p, pPat );
+        // stop if we ran out of room for patterns
+        if ( iWordLim == p->nSimWords )
+            break;
+//        if ( Counter == 1 )
+//            break;
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Get the given number of counter-examples using SAT.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SolveTargetsUsingSat( Sim_Man_t * p, int Limit )
+{
+    Fraig_Params_t Params;
+    Fraig_Man_t * pMan;
+    Abc_Obj_t * pNodeCi;
+    Abc_Ntk_t * pMiter;
+    Sim_Pat_t * pPat;
+    void * pEntry;
+    int * pModel;
+    int RetValue, Output, Input, k, v;
+    int Counter = 0;
+    int clk;
+
+    p->nSatRuns = 0;
+    // put targets into one array
+    Vec_VecForEachEntryReverse( p->vSuppTargs, pEntry, Input, k )
+    {
+        p->nSatRuns++;
+        Output = (int)pEntry;
+
+        // set up the miter for the two cofactors of this output w.r.t. this input
+        pMiter = Abc_NtkMiterForCofactors( p->pNtk, Output, Input, -1 );
+
+        // transform the miter into a fraig
+        Fraig_ParamsSetDefault( &Params );
+        Params.nSeconds = ABC_INFINITY;
+        Params.fInternal = 1;
+clk = clock();
+        pMan = Abc_NtkToFraig( pMiter, &Params, 0, 0 ); 
+p->timeFraig += clock() - clk;
+clk = clock();
+        Fraig_ManProveMiter( pMan );
+p->timeSat += clock() - clk;
+
+        // analyze the result
+        RetValue = Fraig_ManCheckMiter( pMan );
+        assert( RetValue >= 0 );
+        if ( RetValue == 1 ) // unsat
+        {
+            p->nSatRunsUnsat++;
+            pModel = NULL;
+            Vec_PtrRemove( p->vSuppTargs->pArray[Input], pEntry );
+        }
+        else // sat
+        {
+            p->nSatRunsSat++;
+            pModel = Fraig_ManReadModel( pMan );
+            assert( pModel != NULL );
+            assert( Sim_SolveSuppModelVerify( p->pNtk, pModel, Input, Output ) );
+
+//printf( "Solved by SAT (%d,%d).\n", Input, Output );
+            // set the new pattern
+            pPat = Sim_ManPatAlloc( p );
+            pPat->Input  = Input;
+            pPat->Output = Output;
+            Abc_NtkForEachCi( p->pNtk, pNodeCi, v )
+                if ( pModel[v] )
+                    Sim_SetBit( pPat->pData, v );
+            Vec_PtrPush( p->vFifo, pPat );
+/*
+            // set the new pattern
+            pPat = Sim_ManPatAlloc( p );
+            pPat->Input  = Input;
+            pPat->Output = Output;
+            Abc_NtkForEachCi( p->pNtk, pNodeCi, v )
+                if ( pModel[v] )
+                    Sim_SetBit( pPat->pData, v );
+            Sim_XorBit( pPat->pData, Input );  // add this bit in the opposite polarity
+            Vec_PtrPush( p->vFifo, pPat );
+*/
+            Counter++;
+        }
+        // delete the fraig manager
+        Fraig_ManFree( pMan );
+        // delete the miter
+        Abc_NtkDelete( pMiter );
+
+        // makr the input, which we are processing
+        p->iInput = Input;
+
+        // stop when we found enough patterns
+//        if ( Counter == Limit )
+        if ( Counter == 1 )
+            return;
+    }
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Saves the counter example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_NtkSimTwoPats_rec( Abc_Obj_t * pNode )
+{
+    int Value0, Value1;
+    if ( Abc_NodeIsTravIdCurrent( pNode ) )
+        return (int)pNode->pCopy;
+    Abc_NodeSetTravIdCurrent( pNode );
+    Value0 = Sim_NtkSimTwoPats_rec( Abc_ObjFanin0(pNode) );
+    Value1 = Sim_NtkSimTwoPats_rec( Abc_ObjFanin1(pNode) );
+    if ( Abc_ObjFaninC0(pNode) )
+        Value0 = ~Value0;
+    if ( Abc_ObjFaninC1(pNode) )
+        Value1 = ~Value1;
+    pNode->pCopy = (Abc_Obj_t *)(Value0 & Value1);
+    return Value0 & Value1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Verifies that pModel proves the presence of Input in the support of Output.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_SolveSuppModelVerify( Abc_Ntk_t * pNtk, int * pModel, int Input, int Output )
+{
+    Abc_Obj_t * pNode;
+    int RetValue, i;
+    // set the PI values
+    Abc_NtkIncrementTravId( pNtk );
+    Abc_NtkForEachCi( pNtk, pNode, i )
+    {
+        Abc_NodeSetTravIdCurrent( pNode );
+        if ( pNode == Abc_NtkCi(pNtk,Input) )
+            pNode->pCopy = (Abc_Obj_t *)1;
+        else if ( pModel[i] == 1 )
+            pNode->pCopy = (Abc_Obj_t *)3;
+        else
+            pNode->pCopy = NULL;
+    }
+    // perform the traversal
+    RetValue = 3 & Sim_NtkSimTwoPats_rec( Abc_ObjFanin0( Abc_NtkCo(pNtk,Output) ) );
+//    assert( RetValue == 1 || RetValue == 2 ); 
+    return RetValue == 1 || RetValue == 2;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSwitch.c b/src/opt/sim/simSwitch.c
new file mode 100644
index 00000000..218d4d59
--- /dev/null
+++ b/src/opt/sim/simSwitch.c
@@ -0,0 +1,107 @@
+/**CFile****************************************************************
+
+  FileName    [simSwitch.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Computes switching activity of nodes in the ABC network.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simSwitch.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Sim_NodeSimulate( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords );
+static float Sim_ComputeSwitching( unsigned * pSimInfo, int nSimWords );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes switching activity using simulation.]
+
+  Description [Computes switching activity, which is understood as the
+  probability of switching under random simulation. Assigns the
+  random simulation information at the CI and propagates it through
+  the internal nodes of the AIG.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Sim_NtkComputeSwitching( Abc_Ntk_t * pNtk, int nPatterns )
+{
+    Vec_Int_t * vSwitching;
+    float * pSwitching;
+    Vec_Ptr_t * vNodes;
+    Vec_Ptr_t * vSimInfo;
+    Abc_Obj_t * pNode;
+    unsigned * pSimInfo;
+    int nSimWords, i;
+
+    // allocate space for simulation info of all nodes
+    nSimWords = SIM_NUM_WORDS(nPatterns);
+    vSimInfo = Sim_UtilInfoAlloc( Abc_NtkObjNumMax(pNtk), nSimWords, 0 );
+    // assign the random simulation to the CIs
+    vSwitching = Vec_IntStart( Abc_NtkObjNumMax(pNtk) );
+    pSwitching = (float *)vSwitching->pArray;
+    Abc_NtkForEachCi( pNtk, pNode, i )
+    {
+        pSimInfo = Vec_PtrEntry(vSimInfo, pNode->Id);
+        Sim_UtilSetRandom( pSimInfo, nSimWords );
+        pSwitching[pNode->Id] = Sim_ComputeSwitching( pSimInfo, nSimWords );
+    }
+    // simulate the internal nodes
+    vNodes  = Abc_AigDfs( pNtk, 1, 0 );
+    Vec_PtrForEachEntry( vNodes, pNode, i )
+    {
+        pSimInfo = Vec_PtrEntry(vSimInfo, pNode->Id);
+        Sim_UtilSimulateNodeOne( pNode, vSimInfo, nSimWords, 0 );
+        pSwitching[pNode->Id] = Sim_ComputeSwitching( pSimInfo, nSimWords );
+    }
+    Vec_PtrFree( vNodes );
+    Sim_UtilInfoFree( vSimInfo );
+    return vSwitching;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Computes switching activity of one node.]
+
+  Description [Uses the formula: Switching = 2 * nOnes * nZeros / (nTotal ^ 2) ]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+float Sim_ComputeSwitching( unsigned * pSimInfo, int nSimWords )
+{
+    int nOnes, nTotal;
+    nTotal = 32 * nSimWords;
+    nOnes = Sim_UtilCountOnes( pSimInfo, nSimWords );
+    return (float)2.0 * nOnes * (nTotal - nOnes) / nTotal / nTotal;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSym.c b/src/opt/sim/simSym.c
new file mode 100644
index 00000000..71de5b05
--- /dev/null
+++ b/src/opt/sim/simSym.c
@@ -0,0 +1,142 @@
+/**CFile****************************************************************
+
+  FileName    [simSym.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Simulation to determine two-variable symmetries.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simSym.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+ 
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes two variable symmetries.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_ComputeTwoVarSymms( Abc_Ntk_t * pNtk, int fVerbose )
+{
+    Sym_Man_t * p;
+    Vec_Ptr_t * vResult;
+    int Result;
+    int i, clk, clkTotal = clock();
+
+    srand( 0xABC );
+
+    // start the simulation manager
+    p = Sym_ManStart( pNtk, fVerbose );
+    p->nPairsTotal = p->nPairsRem = Sim_UtilCountAllPairs( p->vSuppFun, p->nSimWords, p->vPairsTotal );
+    if ( fVerbose )
+        printf( "Total = %8d.  Sym = %8d.  NonSym = %8d.  Remaining = %8d.\n", 
+               p->nPairsTotal, p->nPairsSymm, p->nPairsNonSymm, p->nPairsRem );
+
+    // detect symmetries using circuit structure
+clk = clock();
+    Sim_SymmsStructCompute( pNtk, p->vMatrSymms, p->vSuppFun );
+p->timeStruct = clock() - clk;
+
+    Sim_UtilCountPairsAll( p );
+    p->nPairsSymmStr = p->nPairsSymm;
+    if ( fVerbose )
+        printf( "Total = %8d.  Sym = %8d.  NonSym = %8d.  Remaining = %8d.\n", 
+            p->nPairsTotal, p->nPairsSymm, p->nPairsNonSymm, p->nPairsRem );
+
+    // detect symmetries using simulation
+    for ( i = 1; i <= 1000; i++ )
+    {
+        // simulate this pattern
+        Sim_UtilSetRandom( p->uPatRand, p->nSimWords );
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+        if ( i % 50 != 0 )
+            continue;
+        // check disjointness
+        assert( Sim_UtilMatrsAreDisjoint( p ) );
+        // count the number of pairs
+        Sim_UtilCountPairsAll( p );
+        if ( i % 500 != 0 )
+            continue;
+        if ( fVerbose )
+            printf( "Total = %8d.  Sym = %8d.  NonSym = %8d.  Remaining = %8d.\n", 
+                p->nPairsTotal, p->nPairsSymm, p->nPairsNonSymm, p->nPairsRem );
+    }
+
+    // detect symmetries using SAT
+    for ( i = 1; Sim_SymmsGetPatternUsingSat( p, p->uPatRand ); i++ )
+    {
+        // simulate this pattern in four polarities
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+        Sim_XorBit( p->uPatRand, p->iVar1 );
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+        Sim_XorBit( p->uPatRand, p->iVar2 );
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+        Sim_XorBit( p->uPatRand, p->iVar1 );
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+        Sim_XorBit( p->uPatRand, p->iVar2 );
+/*
+        // try the previuos pair
+        Sim_XorBit( p->uPatRand, p->iVar1Old );
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+        Sim_XorBit( p->uPatRand, p->iVar2Old );
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+        Sim_XorBit( p->uPatRand, p->iVar1Old );
+        Sim_SymmsSimulate( p, p->uPatRand, p->vMatrNonSymms );
+*/
+        if ( i % 10 != 0 )
+            continue;
+        // check disjointness
+        assert( Sim_UtilMatrsAreDisjoint( p ) );
+        // count the number of pairs
+        Sim_UtilCountPairsAll( p );
+        if ( i % 50 != 0 )
+            continue;
+        if ( fVerbose )
+            printf( "Total = %8d.  Sym = %8d.  NonSym = %8d.  Remaining = %8d.\n", 
+                p->nPairsTotal, p->nPairsSymm, p->nPairsNonSymm, p->nPairsRem );
+    }
+
+    // count the number of pairs
+    Sim_UtilCountPairsAll( p );
+    if ( fVerbose )
+        printf( "Total = %8d.  Sym = %8d.  NonSym = %8d.  Remaining = %8d.\n", 
+            p->nPairsTotal, p->nPairsSymm, p->nPairsNonSymm, p->nPairsRem );
+//    Sim_UtilCountPairsAllPrint( p );
+
+    Result = p->nPairsSymm;
+    vResult = p->vMatrSymms;  
+p->timeTotal = clock() - clkTotal;
+    //  p->vMatrSymms = NULL;
+    Sym_ManStop( p );
+    return Result;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSymSat.c b/src/opt/sim/simSymSat.c
new file mode 100644
index 00000000..7690a891
--- /dev/null
+++ b/src/opt/sim/simSymSat.c
@@ -0,0 +1,199 @@
+/**CFile****************************************************************
+
+  FileName    [simSymSat.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Satisfiability to determine two variable symmetries.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simSymSat.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+#include "fraig.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static int Sim_SymmsSatProveOne( Sym_Man_t * p, int Out, int Var1, int Var2, unsigned * pPattern );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Tries to prove the remaining pairs using SAT.]
+
+  Description [Continues to prove as long as it encounters symmetric pairs.
+  Returns 1 if a non-symmetric pair is found (which gives a counter-example).
+  Returns 0 if it finishes considering all pairs for all outputs.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_SymmsGetPatternUsingSat( Sym_Man_t * p, unsigned * pPattern )
+{
+    Vec_Int_t * vSupport;
+    Extra_BitMat_t * pMatSym, * pMatNonSym;
+    int Index1, Index2, Index3, IndexU, IndexV;
+    int v, u, i, k, b, out;
+
+    // iterate through outputs
+    for ( out = p->iOutput; out < p->nOutputs; out++ )
+    {
+        pMatSym    = Vec_PtrEntry( p->vMatrSymms,    out );
+        pMatNonSym = Vec_PtrEntry( p->vMatrNonSymms, out );
+
+        // go through the remaining variable pairs
+        vSupport = Vec_VecEntry( p->vSupports, out );
+        Vec_IntForEachEntry( vSupport, v, Index1 )
+        Vec_IntForEachEntryStart( vSupport, u, Index2, Index1+1 )
+        {
+            if ( Extra_BitMatrixLookup1( pMatSym, v, u ) || Extra_BitMatrixLookup1( pMatNonSym, v, u ) )
+                continue;
+            p->nSatRuns++;
+
+            // collect the support variables that are symmetric with u and v
+            Vec_IntClear( p->vVarsU );
+            Vec_IntClear( p->vVarsV );
+            Vec_IntForEachEntry( vSupport, b, Index3 )
+            {
+                if ( Extra_BitMatrixLookup1( pMatSym, u, b ) )
+                    Vec_IntPush( p->vVarsU, b );
+                if ( Extra_BitMatrixLookup1( pMatSym, v, b ) )
+                    Vec_IntPush( p->vVarsV, b );
+            }
+
+            if ( Sim_SymmsSatProveOne( p, out, v, u, pPattern ) )
+            { // update the symmetric variable info            
+                p->nSatRunsUnsat++;
+                Vec_IntForEachEntry( p->vVarsU, i, IndexU )
+                Vec_IntForEachEntry( p->vVarsV, k, IndexV )
+                {
+                    Extra_BitMatrixInsert1( pMatSym,  i, k );  // Theorem 1
+                    Extra_BitMatrixInsert2( pMatSym,  i, k );  // Theorem 1
+                    Extra_BitMatrixOrTwo( pMatNonSym, i, k );  // Theorem 2
+                }
+            }
+            else
+            { // update the assymmetric variable info
+                p->nSatRunsSat++;
+                Vec_IntForEachEntry( p->vVarsU, i, IndexU )
+                Vec_IntForEachEntry( p->vVarsV, k, IndexV )
+                {
+                    Extra_BitMatrixInsert1( pMatNonSym, i, k );   // Theorem 3
+                    Extra_BitMatrixInsert2( pMatNonSym, i, k );   // Theorem 3
+                }
+
+                // remember the out
+                p->iOutput = out;
+                p->iVar1Old = p->iVar1;
+                p->iVar2Old = p->iVar2;
+                p->iVar1 = v;
+                p->iVar2 = u;
+                return 1;
+
+            }
+        }
+        // make sure that the symmetry matrix contains only cliques
+        assert( Extra_BitMatrixIsClique( pMatSym ) );
+    }
+
+    // mark that we finished all outputs
+    p->iOutput = p->nOutputs;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the variables are symmetric; 0 otherwise.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_SymmsSatProveOne( Sym_Man_t * p, int Out, int Var1, int Var2, unsigned * pPattern )
+{
+    Fraig_Params_t Params;
+    Fraig_Man_t * pMan;
+    Abc_Ntk_t * pMiter;
+    int RetValue, i, clk;
+    int * pModel;
+
+    // get the miter for this problem
+    pMiter = Abc_NtkMiterForCofactors( p->pNtk, Out, Var1, Var2 );
+    // transform the miter into a fraig
+    Fraig_ParamsSetDefault( &Params );
+    Params.fInternal = 1;
+    Params.nPatsRand = 512;
+    Params.nPatsDyna = 512;
+    Params.nSeconds = ABC_INFINITY;
+
+clk = clock();
+    pMan = Abc_NtkToFraig( pMiter, &Params, 0, 0 ); 
+p->timeFraig += clock() - clk;
+clk = clock();
+    Fraig_ManProveMiter( pMan );
+p->timeSat += clock() - clk;
+
+    // analyze the result
+    RetValue = Fraig_ManCheckMiter( pMan );
+//    assert( RetValue >= 0 );
+    // save the pattern
+    if ( RetValue == 0 )
+    {
+        // get the pattern
+        pModel = Fraig_ManReadModel( pMan );
+        assert( pModel != NULL );
+//printf( "Disproved by SAT: out = %d  pair = (%d, %d)\n", Out, Var1, Var2 );
+        // transfer the model into the pattern
+        for ( i = 0; i < p->nSimWords; i++ )
+            pPattern[i] = 0;
+        for ( i = 0; i < p->nInputs; i++ )
+            if ( pModel[i] )
+                Sim_SetBit( pPattern, i );
+        // make sure these variables have the same value (1)
+        Sim_SetBit( pPattern, Var1 );
+        Sim_SetBit( pPattern, Var2 );
+    }
+    else if ( RetValue == -1 )
+    {
+        // this should never happen; if it happens, such is life
+        // we are conservative and assume that there is no symmetry
+//printf( "STRANGE THING: out = %d %s  pair = (%d %s, %d %s)\n", 
+//                        Out, Abc_ObjName(Abc_NtkCo(p->pNtk,Out)), 
+//                        Var1, Abc_ObjName(Abc_NtkCi(p->pNtk,Var1)), 
+//                        Var2, Abc_ObjName(Abc_NtkCi(p->pNtk,Var2)) );
+        memset( pPattern, 0, sizeof(unsigned) * p->nSimWords );
+        RetValue = 0;
+    }
+    // delete the fraig manager
+    Fraig_ManFree( pMan );
+    // delete the miter
+    Abc_NtkDelete( pMiter );
+    return RetValue;
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSymSim.c b/src/opt/sim/simSymSim.c
new file mode 100644
index 00000000..2282825b
--- /dev/null
+++ b/src/opt/sim/simSymSim.c
@@ -0,0 +1,173 @@
+/**CFile****************************************************************
+
+  FileName    [simSymSim.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Simulation to determine two-variable symmetries.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simSymSim.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+static void Sim_SymmsCreateSquare( Sym_Man_t * p, unsigned * pPat );
+static void Sim_SymmsDeriveInfo( Sym_Man_t * p, unsigned * pPat, Abc_Obj_t * pNode, Vec_Ptr_t * vMatrsNonSym, int Output );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Detects non-symmetric pairs using one pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsSimulate( Sym_Man_t * p, unsigned * pPat, Vec_Ptr_t * vMatrsNonSym )
+{
+    Abc_Obj_t * pNode;
+    int i, nPairsTotal, nPairsSym, nPairsNonSym;
+    int clk;
+
+    // create the simulation matrix
+    Sim_SymmsCreateSquare( p, pPat );
+    // simulate each node in the DFS order
+clk = clock();
+    Vec_PtrForEachEntry( p->vNodes, pNode, i )
+    {
+//        if ( Abc_NodeIsConst(pNode) )
+//            continue;
+        Sim_UtilSimulateNodeOne( pNode, p->vSim, p->nSimWords, 0 );
+    }
+p->timeSim += clock() - clk;
+    // collect info into the CO matrices
+clk = clock();
+    Abc_NtkForEachCo( p->pNtk, pNode, i )
+    {
+        pNode = Abc_ObjFanin0(pNode);
+//        if ( Abc_ObjIsCi(pNode) || Abc_AigNodeIsConst(pNode) )
+//            continue;
+        nPairsTotal  = Vec_IntEntry(p->vPairsTotal, i);
+        nPairsSym    = Vec_IntEntry(p->vPairsSym,   i);
+        nPairsNonSym = Vec_IntEntry(p->vPairsNonSym,i);
+        assert( nPairsTotal >= nPairsSym + nPairsNonSym ); 
+        if ( nPairsTotal == nPairsSym + nPairsNonSym )
+            continue;
+        Sim_SymmsDeriveInfo( p, pPat, pNode, vMatrsNonSym, i );
+    }
+p->timeMatr += clock() - clk;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the square matrix of simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsCreateSquare( Sym_Man_t * p, unsigned * pPat )
+{
+    unsigned * pSimInfo;
+    Abc_Obj_t * pNode;
+    int i, w;
+    // for each PI var copy the pattern
+    Abc_NtkForEachCi( p->pNtk, pNode, i )
+    {
+        pSimInfo = Vec_PtrEntry( p->vSim, pNode->Id );
+        if ( Sim_HasBit(pPat, i) )
+        {
+            for ( w = 0; w < p->nSimWords; w++ )
+                pSimInfo[w] = SIM_MASK_FULL;
+        }
+        else
+        {
+            for ( w = 0; w < p->nSimWords; w++ )
+                pSimInfo[w] = 0;
+        }
+        // flip one bit
+        Sim_XorBit( pSimInfo, i );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transfers the info to the POs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsDeriveInfo( Sym_Man_t * p, unsigned * pPat, Abc_Obj_t * pNode, Vec_Ptr_t * vMatrsNonSym, int Output )
+{
+    Extra_BitMat_t * pMat;
+    Vec_Int_t * vSupport;
+    unsigned * pSupport;
+    unsigned * pSimInfo;
+    int i, w, Index;
+    // get the matrix, the support, and the simulation info
+    pMat = Vec_PtrEntry( vMatrsNonSym, Output );
+    vSupport = Vec_VecEntry( p->vSupports, Output );
+    pSupport = Vec_PtrEntry( p->vSuppFun, Output );
+    pSimInfo = Vec_PtrEntry( p->vSim, pNode->Id );
+    // generate vectors A1 and A2
+    for ( w = 0; w < p->nSimWords; w++ )
+    {
+        p->uPatCol[w] = pSupport[w] & pPat[w] &  pSimInfo[w];
+        p->uPatRow[w] = pSupport[w] & pPat[w] & ~pSimInfo[w];
+    }
+    // add two dimensions
+    Vec_IntForEachEntry( vSupport, i, Index )
+        if ( Sim_HasBit( p->uPatCol, i ) )
+            Extra_BitMatrixOr( pMat, i, p->uPatRow );
+    // add two dimensions
+    Vec_IntForEachEntry( vSupport, i, Index )
+        if ( Sim_HasBit( p->uPatRow, i ) )
+            Extra_BitMatrixOr( pMat, i, p->uPatCol );
+    // generate vectors B1 and B2
+    for ( w = 0; w < p->nSimWords; w++ )
+    {
+        p->uPatCol[w] = pSupport[w] & ~pPat[w] &  pSimInfo[w];
+        p->uPatRow[w] = pSupport[w] & ~pPat[w] & ~pSimInfo[w];
+    }
+    // add two dimensions
+    Vec_IntForEachEntry( vSupport, i, Index )
+        if ( Sim_HasBit( p->uPatCol, i ) )
+            Extra_BitMatrixOr( pMat, i, p->uPatRow );
+    // add two dimensions
+    Vec_IntForEachEntry( vSupport, i, Index )
+        if ( Sim_HasBit( p->uPatRow, i ) )
+            Extra_BitMatrixOr( pMat, i, p->uPatCol );
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simSymStr.c b/src/opt/sim/simSymStr.c
new file mode 100644
index 00000000..d52c4328
--- /dev/null
+++ b/src/opt/sim/simSymStr.c
@@ -0,0 +1,488 @@
+/**CFile****************************************************************
+
+  FileName    [simSymStr.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Structural detection of symmetries.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simSymStr.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+#define SIM_READ_SYMMS(pNode)       ((Vec_Int_t *)pNode->pCopy) 
+#define SIM_SET_SYMMS(pNode,vVect)  (pNode->pCopy = (Abc_Obj_t *)(vVect)) 
+
+static void  Sim_SymmsStructComputeOne( Abc_Ntk_t * pNtk, Abc_Obj_t * pNode, int * pMap );
+static void  Sim_SymmsBalanceCollect_rec( Abc_Obj_t * pNode, Vec_Ptr_t * vNodes );
+static void  Sim_SymmsPartitionNodes( Vec_Ptr_t * vNodes, Vec_Ptr_t * vNodesPis0, Vec_Ptr_t * vNodesPis1, Vec_Ptr_t * vNodesOther );
+static void  Sim_SymmsAppendFromGroup( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodesPi, Vec_Ptr_t * vNodesOther, Vec_Int_t * vSymms, int * pMap );
+static void  Sim_SymmsAppendFromNode( Abc_Ntk_t * pNtk, Vec_Int_t * vSymms0, Vec_Ptr_t * vNodesOther, Vec_Ptr_t * vNodesPi0, Vec_Ptr_t * vNodesPi1, Vec_Int_t * vSymms, int * pMap );
+static int   Sim_SymmsIsCompatibleWithNodes( Abc_Ntk_t * pNtk, unsigned uSymm, Vec_Ptr_t * vNodesOther, int * pMap );
+static int   Sim_SymmsIsCompatibleWithGroup( unsigned uSymm, Vec_Ptr_t * vNodesPi, int * pMap );
+static void  Sim_SymmsPrint( Vec_Int_t * vSymms );
+static void  Sim_SymmsTrans( Vec_Int_t * vSymms );
+static void  Sim_SymmsTransferToMatrix( Extra_BitMat_t * pMatSymm, Vec_Int_t * vSymms, unsigned * pSupport );
+static int * Sim_SymmsCreateMap( Abc_Ntk_t * pNtk );
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes symmetries for a single output function.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsStructCompute( Abc_Ntk_t * pNtk, Vec_Ptr_t * vMatrs, Vec_Ptr_t * vSuppFun )
+{
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pTemp;
+    int * pMap, i;
+
+    assert( Abc_NtkCiNum(pNtk) + 10 < (1<<16) );
+
+    // get the structural support
+    pNtk->vSupps = Sim_ComputeStrSupp( pNtk );
+    // set elementary info for the CIs
+    Abc_NtkForEachCi( pNtk, pTemp, i )
+        SIM_SET_SYMMS( pTemp, Vec_IntAlloc(0) );
+    // create the map of CI ids into their numbers
+    pMap = Sim_SymmsCreateMap( pNtk );
+    // collect the nodes in the TFI cone of this output
+    vNodes = Abc_NtkDfs( pNtk, 0 );
+    Vec_PtrForEachEntry( vNodes, pTemp, i )
+    {
+//        if ( Abc_NodeIsConst(pTemp) )
+//            continue;
+        Sim_SymmsStructComputeOne( pNtk, pTemp, pMap );
+    }
+    // collect the results for the COs;
+    Abc_NtkForEachCo( pNtk, pTemp, i )
+    {
+//printf( "Output %d:\n", i );
+        pTemp = Abc_ObjFanin0(pTemp);
+        if ( Abc_ObjIsCi(pTemp) || Abc_AigNodeIsConst(pTemp) )
+            continue;
+        Sim_SymmsTransferToMatrix( Vec_PtrEntry(vMatrs, i), SIM_READ_SYMMS(pTemp), Vec_PtrEntry(vSuppFun, i) );
+    }
+    // clean the intermediate results
+    Sim_UtilInfoFree( pNtk->vSupps );
+    pNtk->vSupps = NULL;
+    Abc_NtkForEachCi( pNtk, pTemp, i )
+        Vec_IntFree( SIM_READ_SYMMS(pTemp) );
+    Vec_PtrForEachEntry( vNodes, pTemp, i )
+//        if ( !Abc_NodeIsConst(pTemp) )
+            Vec_IntFree( SIM_READ_SYMMS(pTemp) );
+    Vec_PtrFree( vNodes );
+    free( pMap );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Recursively computes symmetries. ]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsStructComputeOne( Abc_Ntk_t * pNtk, Abc_Obj_t * pNode, int * pMap )
+{
+    Vec_Ptr_t * vNodes, * vNodesPi0, * vNodesPi1, * vNodesOther;
+    Vec_Int_t * vSymms;
+    Abc_Obj_t * pTemp;
+    int i;
+
+    // allocate the temporary arrays
+    vNodes      = Vec_PtrAlloc( 10 );
+    vNodesPi0   = Vec_PtrAlloc( 10 );
+    vNodesPi1   = Vec_PtrAlloc( 10 );
+    vNodesOther = Vec_PtrAlloc( 10 );  
+
+    // collect the fanins of the implication supergate
+    Sim_SymmsBalanceCollect_rec( pNode, vNodes );
+
+    // sort the nodes in the implication supergate
+    Sim_SymmsPartitionNodes( vNodes, vNodesPi0, vNodesPi1, vNodesOther );
+
+    // start the resulting set
+    vSymms = Vec_IntAlloc( 10 );
+    // generate symmetries from the groups
+    Sim_SymmsAppendFromGroup( pNtk, vNodesPi0, vNodesOther, vSymms, pMap );
+    Sim_SymmsAppendFromGroup( pNtk, vNodesPi1, vNodesOther, vSymms, pMap );
+    // add symmetries from other inputs
+    for ( i = 0; i < vNodesOther->nSize; i++ )
+    {
+        pTemp = Abc_ObjRegular(vNodesOther->pArray[i]);
+        Sim_SymmsAppendFromNode( pNtk, SIM_READ_SYMMS(pTemp), vNodesOther, vNodesPi0, vNodesPi1, vSymms, pMap );
+    }
+    Vec_PtrFree( vNodes );
+    Vec_PtrFree( vNodesPi0 );
+    Vec_PtrFree( vNodesPi1 );
+    Vec_PtrFree( vNodesOther );
+
+    // set the symmetry at the node
+    SIM_SET_SYMMS( pNode, vSymms );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the array of nodes to be combined into one multi-input AND-gate.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsBalanceCollect_rec( Abc_Obj_t * pNode, Vec_Ptr_t * vNodes )
+{
+    // if the new node is complemented, another gate begins
+    if ( Abc_ObjIsComplement(pNode) )
+    {
+        Vec_PtrPushUnique( vNodes, pNode );
+        return;
+    }
+    // if pNew is the PI node, return
+    if ( Abc_ObjIsCi(pNode) )
+    {
+        Vec_PtrPushUnique( vNodes, pNode );
+        return;    
+    }
+    // go through the branches
+    Sim_SymmsBalanceCollect_rec( Abc_ObjChild0(pNode), vNodes );
+    Sim_SymmsBalanceCollect_rec( Abc_ObjChild1(pNode), vNodes );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Divides PI variables into groups.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsPartitionNodes( Vec_Ptr_t * vNodes, Vec_Ptr_t * vNodesPis0, 
+    Vec_Ptr_t * vNodesPis1, Vec_Ptr_t * vNodesOther )
+{
+    Abc_Obj_t * pNode;
+    int i;
+    Vec_PtrForEachEntry( vNodes, pNode, i )
+    {
+        if ( !Abc_ObjIsCi(Abc_ObjRegular(pNode)) )
+            Vec_PtrPush( vNodesOther, pNode );
+        else if ( Abc_ObjIsComplement(pNode) )
+            Vec_PtrPush( vNodesPis0, pNode );
+        else
+            Vec_PtrPush( vNodesPis1, pNode );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Makes the product of two partitions.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsAppendFromGroup( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodesPi, Vec_Ptr_t * vNodesOther, Vec_Int_t * vSymms, int * pMap )
+{
+    Abc_Obj_t * pNode1, * pNode2;
+    unsigned uSymm;
+    int i, k;
+
+    if ( vNodesPi->nSize == 0 )
+        return;
+
+    // go through the pairs
+    for ( i = 0; i < vNodesPi->nSize; i++ )
+    for ( k = i+1; k < vNodesPi->nSize; k++ )
+    {
+        // get the two PI nodes
+        pNode1 = Abc_ObjRegular(vNodesPi->pArray[i]);
+        pNode2 = Abc_ObjRegular(vNodesPi->pArray[k]);
+        assert( pMap[pNode1->Id] != pMap[pNode2->Id] );
+        assert( pMap[pNode1->Id] >= 0 );
+        assert( pMap[pNode2->Id] >= 0 );
+        // generate symmetry
+        if ( pMap[pNode1->Id] < pMap[pNode2->Id] )
+            uSymm = ((pMap[pNode1->Id] << 16) | pMap[pNode2->Id]);
+        else
+            uSymm = ((pMap[pNode2->Id] << 16) | pMap[pNode1->Id]);
+        // check if symmetry belongs
+        if ( Sim_SymmsIsCompatibleWithNodes( pNtk, uSymm, vNodesOther, pMap ) )
+            Vec_IntPushUnique( vSymms, (int)uSymm );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Add the filters symmetries from the nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsAppendFromNode( Abc_Ntk_t * pNtk, Vec_Int_t * vSymms0, Vec_Ptr_t * vNodesOther, 
+    Vec_Ptr_t * vNodesPi0, Vec_Ptr_t * vNodesPi1, Vec_Int_t * vSymms, int * pMap )
+{
+    unsigned uSymm;
+    int i;
+
+    if ( vSymms0->nSize == 0 )
+        return;
+
+    // go through the pairs
+    for ( i = 0; i < vSymms0->nSize; i++ )
+    {
+        uSymm = (unsigned)vSymms0->pArray[i];
+        // check if symmetry belongs
+        if ( Sim_SymmsIsCompatibleWithNodes( pNtk, uSymm, vNodesOther, pMap ) &&
+             Sim_SymmsIsCompatibleWithGroup( uSymm, vNodesPi0, pMap ) && 
+             Sim_SymmsIsCompatibleWithGroup( uSymm, vNodesPi1, pMap ) )
+            Vec_IntPushUnique( vSymms, (int)uSymm );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if symmetry is compatible with the group of nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_SymmsIsCompatibleWithNodes( Abc_Ntk_t * pNtk, unsigned uSymm, Vec_Ptr_t * vNodesOther, int * pMap )
+{
+    Vec_Int_t * vSymmsNode;
+    Abc_Obj_t * pNode;
+    int i, s, Ind1, Ind2, fIsVar1, fIsVar2;
+
+    if ( vNodesOther->nSize == 0 )
+        return 1;
+
+    // get the indices of the PI variables
+    Ind1 = (uSymm & 0xffff);
+    Ind2 = (uSymm >> 16);
+
+    // go through the nodes
+    // if they do not belong to a support, it is okay
+    // if one belongs, the other does not belong, quit
+    // if they belong, but are not part of symmetry, quit
+    for ( i = 0; i < vNodesOther->nSize; i++ )
+    {
+        pNode = Abc_ObjRegular(vNodesOther->pArray[i]);
+        fIsVar1 = Sim_SuppStrHasVar( pNtk->vSupps, pNode, Ind1 );
+        fIsVar2 = Sim_SuppStrHasVar( pNtk->vSupps, pNode, Ind2 );
+
+        if ( !fIsVar1 && !fIsVar2 )
+            continue;
+        if ( fIsVar1 ^ fIsVar2 )
+            return 0;
+        // both belong
+        // check if there is a symmetry
+        vSymmsNode = SIM_READ_SYMMS( pNode );
+        for ( s = 0; s < vSymmsNode->nSize; s++ )
+            if ( uSymm == (unsigned)vSymmsNode->pArray[s] )
+                break;
+        if ( s == vSymmsNode->nSize )
+            return 0;
+    }
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if symmetry is compatible with the group of PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_SymmsIsCompatibleWithGroup( unsigned uSymm, Vec_Ptr_t * vNodesPi, int * pMap )
+{
+    Abc_Obj_t * pNode;
+    int i, Ind1, Ind2, fHasVar1, fHasVar2;
+
+    if ( vNodesPi->nSize == 0 )
+        return 1;
+
+    // get the indices of the PI variables
+    Ind1 = (uSymm & 0xffff);
+    Ind2 = (uSymm >> 16);
+
+    // go through the PI nodes
+    fHasVar1 = fHasVar2 = 0;
+    for ( i = 0; i < vNodesPi->nSize; i++ )
+    {
+        pNode = Abc_ObjRegular(vNodesPi->pArray[i]);
+        if ( pMap[pNode->Id] == Ind1 )
+            fHasVar1 = 1;
+        else if ( pMap[pNode->Id] == Ind2 )
+            fHasVar2 = 1;
+    }
+    return fHasVar1 == fHasVar2;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Improvements due to transitivity.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsTrans( Vec_Int_t * vSymms )
+{
+    unsigned uSymm, uSymma, uSymmr;
+    int i, Ind1, Ind2;
+    int k, Ind1a, Ind2a;
+    int j;
+    int nTrans = 0;
+
+    for ( i = 0; i < vSymms->nSize; i++ )
+    {
+        uSymm = (unsigned)vSymms->pArray[i];
+        Ind1 = (uSymm & 0xffff);
+        Ind2 = (uSymm >> 16);
+        // find other symmetries that have Ind1
+        for ( k = i+1; k < vSymms->nSize; k++ )
+        {
+            uSymma = (unsigned)vSymms->pArray[k];
+            if ( uSymma == uSymm )
+                continue;
+            Ind1a = (uSymma & 0xffff);
+            Ind2a = (uSymma >> 16);
+            if ( Ind1a == Ind1 )
+            {
+                // find the symmetry (Ind2,Ind2a)
+                if ( Ind2 < Ind2a )
+                    uSymmr = ((Ind2 << 16) | Ind2a);
+                else
+                    uSymmr = ((Ind2a << 16) | Ind2);
+                for ( j = 0; j < vSymms->nSize; j++ )
+                    if ( uSymmr == (unsigned)vSymms->pArray[j] )
+                        break;
+                if ( j == vSymms->nSize )
+                    nTrans++;
+            }
+        }
+
+    }
+    printf( "Trans = %d.\n", nTrans );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Transfers from the vector to the matrix.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_SymmsTransferToMatrix( Extra_BitMat_t * pMatSymm, Vec_Int_t * vSymms, unsigned * pSupport )
+{
+    int i, Ind1, Ind2, nInputs;
+    unsigned uSymm;
+    // add diagonal elements
+    nInputs = Extra_BitMatrixReadSize( pMatSymm );
+    for ( i = 0; i < nInputs; i++ )
+        Extra_BitMatrixInsert1( pMatSymm, i, i );
+    // add non-diagonal elements
+    for ( i = 0; i < vSymms->nSize; i++ )
+    {
+        uSymm = (unsigned)vSymms->pArray[i];
+        Ind1 = (uSymm & 0xffff);
+        Ind2 = (uSymm >> 16);
+//printf( "%d,%d ", Ind1, Ind2 );
+        // skip variables that are not in the true support
+        assert( Sim_HasBit(pSupport, Ind1) == Sim_HasBit(pSupport, Ind2) );
+        if ( !Sim_HasBit(pSupport, Ind1) || !Sim_HasBit(pSupport, Ind2) )
+            continue;
+        Extra_BitMatrixInsert1( pMatSymm, Ind1, Ind2 );
+        Extra_BitMatrixInsert2( pMatSymm, Ind1, Ind2 );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Mapping of indices into numbers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int * Sim_SymmsCreateMap( Abc_Ntk_t * pNtk )
+{
+    int * pMap;
+    Abc_Obj_t * pNode;
+    int i;
+    pMap = ALLOC( int, Abc_NtkObjNumMax(pNtk) );
+    for ( i = 0; i < Abc_NtkObjNumMax(pNtk); i++ )
+        pMap[i] = -1;
+    Abc_NtkForEachCi( pNtk, pNode, i )
+        pMap[pNode->Id] = i;
+    return pMap;
+}
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/opt/sim/simUtils.c b/src/opt/sim/simUtils.c
new file mode 100644
index 00000000..b0660001
--- /dev/null
+++ b/src/opt/sim/simUtils.c
@@ -0,0 +1,711 @@
+/**CFile****************************************************************
+
+  FileName    [simUtils.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Network and node package.]
+
+  Synopsis    [Various simulation utilities.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: simUtils.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "abc.h"
+#include "sim.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+ 
+static int bit_count[256] = {
+  0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,
+  1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
+  1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
+  2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
+  1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
+  2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
+  2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
+  3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,4,5,5,6,5,6,6,7,5,6,6,7,6,7,7,8
+};
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates simulation information for all nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Sim_UtilInfoAlloc( int nSize, int nWords, bool fClean )
+{
+    Vec_Ptr_t * vInfo;
+    int i;
+    assert( nSize > 0 && nWords > 0 );
+    vInfo = Vec_PtrAlloc( nSize );
+    vInfo->pArray[0] = ALLOC( unsigned, nSize * nWords );
+    if ( fClean )
+        memset( vInfo->pArray[0], 0, sizeof(unsigned) * nSize * nWords );
+    for ( i = 1; i < nSize; i++ )
+        vInfo->pArray[i] = ((unsigned *)vInfo->pArray[i-1]) + nWords;
+    vInfo->nSize = nSize;
+    return vInfo;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates simulation information for all nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilInfoFree( Vec_Ptr_t * p )
+{
+    free( p->pArray[0] );
+    Vec_PtrFree( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Adds the second supp-info the first.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilInfoAdd( unsigned * pInfo1, unsigned * pInfo2, int nWords )
+{
+    int w;
+    for ( w = 0; w < nWords; w++ )
+        pInfo1[w] |= pInfo2[w];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the positions where pInfo2 is 1 while pInfo1 is 0.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilInfoDetectDiffs( unsigned * pInfo1, unsigned * pInfo2, int nWords, Vec_Int_t * vDiffs )
+{
+    int w, b;
+    unsigned uMask;
+    vDiffs->nSize = 0;
+    for ( w = 0; w < nWords; w++ )
+        if ( uMask = (pInfo2[w] ^ pInfo1[w]) )
+            for ( b = 0; b < 32; b++ )
+                if ( uMask & (1 << b) )
+                    Vec_IntPush( vDiffs, 32*w + b );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns the positions where pInfo2 is 1 while pInfo1 is 0.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilInfoDetectNews( unsigned * pInfo1, unsigned * pInfo2, int nWords, Vec_Int_t * vDiffs )
+{
+    int w, b;
+    unsigned uMask;
+    vDiffs->nSize = 0;
+    for ( w = 0; w < nWords; w++ )
+        if ( uMask = (pInfo2[w] & ~pInfo1[w]) )
+            for ( b = 0; b < 32; b++ )
+                if ( uMask & (1 << b) )
+                    Vec_IntPush( vDiffs, 32*w + b );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Flips the simulation info of the node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilInfoFlip( Sim_Man_t * p, Abc_Obj_t * pNode )
+{
+    unsigned * pSimInfo1, * pSimInfo2;
+    int k;
+    pSimInfo1 = p->vSim0->pArray[pNode->Id];
+    pSimInfo2 = p->vSim1->pArray[pNode->Id];
+    for ( k = 0; k < p->nSimWords; k++ )
+        pSimInfo2[k] = ~pSimInfo1[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the simulation infos are equal.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+bool Sim_UtilInfoCompare( Sim_Man_t * p, Abc_Obj_t * pNode )
+{
+    unsigned * pSimInfo1, * pSimInfo2;
+    int k;
+    pSimInfo1 = p->vSim0->pArray[pNode->Id];
+    pSimInfo2 = p->vSim1->pArray[pNode->Id];
+    for ( k = 0; k < p->nSimWords; k++ )
+        if ( pSimInfo2[k] != pSimInfo1[k] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates the internal nodes.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilSimulate( Sim_Man_t * p, bool fType )
+{
+    Abc_Obj_t * pNode;
+    int i;
+    // simulate the internal nodes
+    Abc_NtkForEachNode( p->pNtk, pNode, i )
+        Sim_UtilSimulateNode( p, pNode, fType, fType, fType );
+    // assign simulation info of the CO nodes
+    Abc_NtkForEachCo( p->pNtk, pNode, i )
+        Sim_UtilSimulateNode( p, pNode, fType, fType, fType );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilSimulateNode( Sim_Man_t * p, Abc_Obj_t * pNode, bool fType, bool fType1, bool fType2 )
+{
+    unsigned * pSimmNode, * pSimmNode1, * pSimmNode2;
+    int k, fComp1, fComp2;
+    // simulate the internal nodes
+    if ( Abc_ObjIsNode(pNode) )
+    {
+        if ( fType )
+            pSimmNode  = p->vSim1->pArray[ pNode->Id ];
+        else
+            pSimmNode  = p->vSim0->pArray[ pNode->Id ];
+
+        if ( fType1 )
+            pSimmNode1 = p->vSim1->pArray[ Abc_ObjFaninId0(pNode) ];
+        else
+            pSimmNode1 = p->vSim0->pArray[ Abc_ObjFaninId0(pNode) ];
+
+        if ( fType2 )
+            pSimmNode2 = p->vSim1->pArray[ Abc_ObjFaninId1(pNode) ];
+        else
+            pSimmNode2 = p->vSim0->pArray[ Abc_ObjFaninId1(pNode) ];
+
+        fComp1 = Abc_ObjFaninC0(pNode);
+        fComp2 = Abc_ObjFaninC1(pNode);
+        if ( fComp1 && fComp2 )
+            for ( k = 0; k < p->nSimWords; k++ )
+                pSimmNode[k] = ~pSimmNode1[k] & ~pSimmNode2[k];
+        else if ( fComp1 && !fComp2 )
+            for ( k = 0; k < p->nSimWords; k++ )
+                pSimmNode[k] = ~pSimmNode1[k] &  pSimmNode2[k];
+        else if ( !fComp1 && fComp2 )
+            for ( k = 0; k < p->nSimWords; k++ )
+                pSimmNode[k] =  pSimmNode1[k] & ~pSimmNode2[k];
+        else // if ( fComp1 && fComp2 )
+            for ( k = 0; k < p->nSimWords; k++ )
+                pSimmNode[k] =  pSimmNode1[k] &  pSimmNode2[k];
+    }
+    else 
+    {
+        assert( Abc_ObjFaninNum(pNode) == 1 );
+        if ( fType )
+            pSimmNode  = p->vSim1->pArray[ pNode->Id ];
+        else
+            pSimmNode  = p->vSim0->pArray[ pNode->Id ];
+
+        if ( fType1 )
+            pSimmNode1 = p->vSim1->pArray[ Abc_ObjFaninId0(pNode) ];
+        else
+            pSimmNode1 = p->vSim0->pArray[ Abc_ObjFaninId0(pNode) ];
+
+        fComp1 = Abc_ObjFaninC0(pNode);
+        if ( fComp1 )
+            for ( k = 0; k < p->nSimWords; k++ )
+                pSimmNode[k] = ~pSimmNode1[k];
+        else 
+            for ( k = 0; k < p->nSimWords; k++ )
+                pSimmNode[k] =  pSimmNode1[k];
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilSimulateNodeOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords, int nOffset )
+{
+    unsigned * pSimmNode, * pSimmNode1, * pSimmNode2;
+    int k, fComp1, fComp2;
+    // simulate the internal nodes
+    assert( Abc_ObjIsNode(pNode) );
+    pSimmNode  = Vec_PtrEntry(vSimInfo, pNode->Id);
+    pSimmNode1 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId0(pNode));
+    pSimmNode2 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId1(pNode));
+    pSimmNode  += nOffset;
+    pSimmNode1 += nOffset;
+    pSimmNode2 += nOffset;
+    fComp1 = Abc_ObjFaninC0(pNode);
+    fComp2 = Abc_ObjFaninC1(pNode);
+    if ( fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pSimmNode[k] = ~pSimmNode1[k] & ~pSimmNode2[k];
+    else if ( fComp1 && !fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pSimmNode[k] = ~pSimmNode1[k] &  pSimmNode2[k];
+    else if ( !fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pSimmNode[k] =  pSimmNode1[k] & ~pSimmNode2[k];
+    else // if ( fComp1 && fComp2 )
+        for ( k = 0; k < nSimWords; k++ )
+            pSimmNode[k] =  pSimmNode1[k] &  pSimmNode2[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilTransferNodeOne( Abc_Obj_t * pNode, Vec_Ptr_t * vSimInfo, int nSimWords, int nOffset, int fShift )
+{
+    unsigned * pSimmNode, * pSimmNode1;
+    int k, fComp1;
+    // simulate the internal nodes
+    assert( Abc_ObjIsCo(pNode) );
+    pSimmNode  = Vec_PtrEntry(vSimInfo, pNode->Id);
+    pSimmNode1 = Vec_PtrEntry(vSimInfo, Abc_ObjFaninId0(pNode));
+    pSimmNode  += nOffset + (fShift > 0)*nSimWords;
+    pSimmNode1 += nOffset;
+    fComp1 = Abc_ObjFaninC0(pNode);
+    if ( fComp1 )
+        for ( k = 0; k < nSimWords; k++ )
+            pSimmNode[k] = ~pSimmNode1[k];
+    else 
+        for ( k = 0; k < nSimWords; k++ )
+            pSimmNode[k] =  pSimmNode1[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the simulation infos are equal.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilCountSuppSizes( Sim_Man_t * p, int fStruct )
+{
+    Abc_Obj_t * pNode, * pNodeCi;
+    int i, v, Counter;
+    Counter = 0;
+    if ( fStruct )
+    {
+        Abc_NtkForEachCo( p->pNtk, pNode, i )
+            Abc_NtkForEachCi( p->pNtk, pNodeCi, v )
+                Counter += Sim_SuppStrHasVar( p->vSuppStr, pNode, v );
+    }
+    else
+    {
+        Abc_NtkForEachCo( p->pNtk, pNode, i )
+            Abc_NtkForEachCi( p->pNtk, pNodeCi, v )
+                Counter += Sim_SuppFunHasVar( p->vSuppFun, i, v );
+    }
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of 1's in the bitstring.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilCountOnes( unsigned * pSimInfo, int nSimWords )
+{
+    unsigned char * pBytes;
+    int nOnes, nBytes, i;
+    pBytes = (unsigned char *)pSimInfo;
+    nBytes = 4 * nSimWords;
+    nOnes  = 0;
+    for ( i = 0; i < nBytes; i++ )
+        nOnes += bit_count[ pBytes[i] ];
+    return nOnes;    
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of 1's in the bitstring.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Sim_UtilCountOnesArray( Vec_Ptr_t * vInfo, int nSimWords )
+{
+    Vec_Int_t * vCounters;
+    unsigned * pSimInfo;
+    int i;
+    vCounters = Vec_IntStart( Vec_PtrSize(vInfo) );
+    Vec_PtrForEachEntry( vInfo, pSimInfo, i )
+        Vec_IntWriteEntry( vCounters, i, Sim_UtilCountOnes(pSimInfo, nSimWords) );
+    return vCounters;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns random patterns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilSetRandom( unsigned * pPatRand, int nSimWords )
+{
+    int k;
+    for ( k = 0; k < nSimWords; k++ )
+        pPatRand[k] = SIM_RANDOM_UNSIGNED;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns complemented patterns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilSetCompl( unsigned * pPatRand, int nSimWords )
+{
+    int k;
+    for ( k = 0; k < nSimWords; k++ )
+        pPatRand[k] = ~pPatRand[k];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns constant patterns.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilSetConst( unsigned * pPatRand, int nSimWords, int fConst1 )
+{
+    int k;
+    for ( k = 0; k < nSimWords; k++ )
+        pPatRand[k] = 0;
+    if ( fConst1 )
+        Sim_UtilSetCompl( pPatRand, nSimWords );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if equal.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilInfoIsEqual( unsigned * pPats1, unsigned * pPats2, int nSimWords )
+{
+    int k;
+    for ( k = 0; k < nSimWords; k++ )
+        if ( pPats1[k] != pPats2[k] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if Node1 implies Node2.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilInfoIsImp( unsigned * pPats1, unsigned * pPats2, int nSimWords )
+{
+    int k;
+    for ( k = 0; k < nSimWords; k++ )
+        if ( pPats1[k] & ~pPats2[k] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if Node1 v Node2 is always true.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilInfoIsClause( unsigned * pPats1, unsigned * pPats2, int nSimWords )
+{
+    int k;
+    for ( k = 0; k < nSimWords; k++ )
+        if ( ~pPats1[k] & ~pPats2[k] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the total number of pairs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilCountAllPairs( Vec_Ptr_t * vSuppFun, int nSimWords, Vec_Int_t * vCounters )
+{
+    unsigned * pSupp;
+    int Counter, nOnes, nPairs, i;
+    Counter = 0;
+    Vec_PtrForEachEntry( vSuppFun, pSupp, i )
+    {
+        nOnes  = Sim_UtilCountOnes( pSupp, nSimWords );
+        nPairs = nOnes * (nOnes - 1) / 2;
+        Vec_IntWriteEntry( vCounters, i, nPairs );
+        Counter += nPairs;
+    }
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of entries in the array of matrices.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilCountPairsOne( Extra_BitMat_t * pMat, Vec_Int_t * vSupport )
+{
+    int i, k, Index1, Index2;
+    int Counter = 0;
+//    int Counter2;
+    Vec_IntForEachEntry( vSupport, i, Index1 )
+    Vec_IntForEachEntryStart( vSupport, k, Index2, Index1+1 )
+        Counter += Extra_BitMatrixLookup1( pMat, i, k );
+//    Counter2 = Extra_BitMatrixCountOnesUpper(pMat);
+//    assert( Counter == Counter2 );
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of entries in the array of matrices.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilCountPairsOnePrint( Extra_BitMat_t * pMat, Vec_Int_t * vSupport )
+{
+    int i, k, Index1, Index2;
+    Vec_IntForEachEntry( vSupport, i, Index1 )
+    Vec_IntForEachEntryStart( vSupport, k, Index2, Index1+1 )
+        if ( Extra_BitMatrixLookup1( pMat, i, k ) )
+            printf( "(%d,%d) ", i, k );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of entries in the array of matrices.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilCountPairsAllPrint( Sym_Man_t * p )
+{
+    int i, clk;
+clk = clock();
+    for ( i = 0; i < p->nOutputs; i++ )
+    {
+        printf( "Output %2d :", i );
+        Sim_UtilCountPairsOnePrint( Vec_PtrEntry(p->vMatrSymms, i), Vec_VecEntry(p->vSupports, i) );
+        printf( "\n" );
+    }
+p->timeCount += clock() - clk;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of entries in the array of matrices.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Sim_UtilCountPairsAll( Sym_Man_t * p )
+{
+    int nPairsTotal, nPairsSym, nPairsNonSym, i, clk;
+clk = clock();
+    p->nPairsSymm    = 0;
+    p->nPairsNonSymm = 0;
+    for ( i = 0; i < p->nOutputs; i++ )
+    {
+        nPairsTotal  = Vec_IntEntry(p->vPairsTotal, i);
+        nPairsSym    = Vec_IntEntry(p->vPairsSym,   i);
+        nPairsNonSym = Vec_IntEntry(p->vPairsNonSym,i);
+        assert( nPairsTotal >= nPairsSym + nPairsNonSym ); 
+        if ( nPairsTotal == nPairsSym + nPairsNonSym )
+        {
+            p->nPairsSymm    += nPairsSym;
+            p->nPairsNonSymm += nPairsNonSym;
+            continue;
+        }
+        nPairsSym    = Sim_UtilCountPairsOne( Vec_PtrEntry(p->vMatrSymms,   i), Vec_VecEntry(p->vSupports, i) );
+        nPairsNonSym = Sim_UtilCountPairsOne( Vec_PtrEntry(p->vMatrNonSymms,i), Vec_VecEntry(p->vSupports, i) );
+        assert( nPairsTotal >= nPairsSym + nPairsNonSym ); 
+        Vec_IntWriteEntry( p->vPairsSym,    i, nPairsSym );
+        Vec_IntWriteEntry( p->vPairsNonSym, i, nPairsNonSym );
+        p->nPairsSymm    += nPairsSym;
+        p->nPairsNonSymm += nPairsNonSym;
+//        printf( "%d ", nPairsTotal - nPairsSym - nPairsNonSym );
+    }
+//printf( "\n" );
+    p->nPairsRem = p->nPairsTotal-p->nPairsSymm-p->nPairsNonSymm;
+p->timeCount += clock() - clk;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Sim_UtilMatrsAreDisjoint( Sym_Man_t * p )
+{
+    int i;
+    for ( i = 0; i < p->nOutputs; i++ )
+        if ( !Extra_BitMatrixIsDisjoint( Vec_PtrEntry(p->vMatrSymms,i), Vec_PtrEntry(p->vMatrNonSymms,i) ) )
+            return 0;
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+