Version abc90315

11 files changed, 1344 insertions, 91 deletions

diff --git a/abclib.dsp b/abclib.dsp
index 978497a3..17600b4c 100644
--- a/abclib.dsp
+++ b/abclib.dsp
@@ -3651,6 +3651,14 @@ SOURCE=.\src\aig\gia\giaCof.c
 # End Source File
 # Begin Source File
 
+SOURCE=.\src\aig\gia\giaCSat0.c
+# End Source File
+# Begin Source File
+
+SOURCE=.\src\aig\gia\giaCSat2.c
+# End Source File
+# Begin Source File
+
 SOURCE=.\src\aig\gia\giaDfs.c
 # End Source File
 # Begin Source File
diff --git a/src/aig/cec/cecCore.c b/src/aig/cec/cecCore.c
index 8e66179f..9274dcb8 100644
--- a/src/aig/cec/cecCore.c
+++ b/src/aig/cec/cecCore.c
@@ -282,6 +282,9 @@ p->timeSim += clock() - clk;
 //            Gia_ManEquivTransform( p->pAig, 1 );
         }
         pSrm = Cec_ManFraSpecReduction( p ); 
+
+//        Gia_WriteAiger( pSrm, "gia_srm.aig", 0, 0 );
+
         if ( pPars->fVeryVerbose )
             Gia_ManPrintStats( pSrm );
         if ( Gia_ManCoNum(pSrm) == 0 )
diff --git a/src/aig/gia/gia.h b/src/aig/gia/gia.h
index 1c3529ba..e3b3f014 100644
--- a/src/aig/gia/gia.h
+++ b/src/aig/gia/gia.h
@@ -435,14 +435,15 @@ static inline int *      Gia_ObjGateFanins( Gia_Man_t * p, int Id )         { re
 ///                    FUNCTION DECLARATIONS                         ///
 ////////////////////////////////////////////////////////////////////////
 
-/*=== giaAig.c ============================================================*/
+/*=== giaAig.c =============================================================*/
 extern Gia_Man_t *         Gia_ManFromAig( Aig_Man_t * p );
 extern Gia_Man_t *         Gia_ManFromAigSwitch( Aig_Man_t * p );
 extern Aig_Man_t *         Gia_ManToAig( Gia_Man_t * p );
-/*=== giaAiger.c ==========================================================*/
+/*=== giaAiger.c ===========================================================*/
 extern Gia_Man_t *         Gia_ReadAiger( char * pFileName, int fCheck );
 extern void                Gia_WriteAiger( Gia_Man_t * p, char * pFileName, int fWriteSymbols, int fCompact );
-/*=== giaCof.c ============================================================*/
+/*=== giaCsat.c ============================================================*/
+/*=== giaCof.c =============================================================*/
 extern void                Gia_ManPrintFanio( Gia_Man_t * pGia, int nNodes );
 extern Gia_Man_t *         Gia_ManDupCof( Gia_Man_t * p, int iVar );
 extern Gia_Man_t *         Gia_ManDupCofAllInt( Gia_Man_t * p, Vec_Int_t * vSigs, int fVerbose );
diff --git a/src/aig/gia/giaCSat0.c b/src/aig/gia/giaCSat0.c
index 599ad43c..a0d567a2 100644
--- a/src/aig/gia/giaCSat0.c
+++ b/src/aig/gia/giaCSat0.c
@@ -122,8 +122,10 @@ void Gia_SatVerifyPattern( Gia_Man_t * p, Gia_Obj_t * pRoot, Vec_Int_t * vCex, V
     }
     Value = Gia_XsimNotCond( Value, Gia_ObjFaninC0(pRoot) );
     if ( Value != GIA_ONE )
-        printf( "Gia_SatVerifyPattern(): Verification failed.\n" );
-    assert( Value == GIA_ONE );
+        printf( "Gia_SatVerifyPattern(): Verification FAILED.\n" );
+//    else
+//        printf( "Gia_SatVerifyPattern(): Verification succeeded.\n" );
+//    assert( Value == GIA_ONE );
     // clean the nodes
     Gia_ManForEachObjVec( vVisit, p, pObj, i )
         Sat_ObjSetXValue( pObj, 0 );
diff --git a/src/aig/gia/giaCSat2.c b/src/aig/gia/giaCSat2.c
new file mode 100644
index 00000000..1e7cc949
--- /dev/null
+++ b/src/aig/gia/giaCSat2.c
@@ -0,0 +1,745 @@
+/**CFile****************************************************************
+
+  FileName    [giaCSat2.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Scalable AIG package.]
+
+  Synopsis    [A simple circuit-based solver.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 20, 2005.]
+
+  Revision    [$Id: giaCSat2.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "gia.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Cbs_Par_t_ Cbs_Par_t;
+struct Cbs_Par_t_
+{
+    // conflict limits
+    int           nBTLimit;     // limit on the number of conflicts
+    int           nJustLimit;   // limit on the size of justification queue
+    // current parameters
+    int           nBTThis;      // number of conflicts
+    int           nJustThis;    // max size of the frontier
+    int           nBTTotal;     // total number of conflicts
+    int           nJustTotal;   // total size of the frontier
+    // decision heuristics
+    int           fUseHighest;  // use node with the highest ID
+    int           fUseLowest;   // use node with the highest ID
+    int           fUseMaxFF;    // use node with the largest fanin fanout
+    // other
+    int           fVerbose;
+};
+
+typedef struct Cbs_Que_t_ Cbs_Que_t;
+struct Cbs_Que_t_
+{
+    int           iHead;        // beginning of the queue
+    int           iTail;        // end of the queue
+    int           nSize;        // allocated size
+    Gia_Obj_t **  pData;        // nodes stored in the queue
+};
+
+typedef struct Cbs_Man_t_ Cbs_Man_t;
+struct Cbs_Man_t_
+{
+    Cbs_Par_t     Pars;         // parameters
+    Gia_Man_t *   pAig;         // AIG manager
+    Cbs_Que_t     pProp;        // propagation queue
+    Cbs_Que_t     pJust;        // justification queue
+    Vec_Int_t *   vModel;       // satisfying assignment
+};
+
+static inline int   Cbs_VarIsAssigned( Gia_Obj_t * pVar )      { return pVar->fMark0;                        }
+static inline void  Cbs_VarAssign( Gia_Obj_t * pVar )          { assert(!pVar->fMark0); pVar->fMark0 = 1;    }
+static inline void  Cbs_VarUnassign( Gia_Obj_t * pVar )        { assert(pVar->fMark0);  pVar->fMark0 = 0; pVar->fMark1 = 0;         }
+static inline int   Cbs_VarValue( Gia_Obj_t * pVar )           { assert(pVar->fMark0);  return pVar->fMark1; }
+static inline void  Cbs_VarSetValue( Gia_Obj_t * pVar, int v ) { assert(pVar->fMark0);  pVar->fMark1 = v;    }
+static inline int   Cbs_VarIsJust( Gia_Obj_t * pVar )          { return Gia_ObjIsAnd(pVar) && !Cbs_VarIsAssigned(Gia_ObjFanin0(pVar)) && !Cbs_VarIsAssigned(Gia_ObjFanin1(pVar)); } 
+static inline int   Cbs_VarFanin0Value( Gia_Obj_t * pVar )     { return !Cbs_VarIsAssigned(Gia_ObjFanin0(pVar)) ? 2 : (Cbs_VarValue(Gia_ObjFanin0(pVar)) ^ Gia_ObjFaninC0(pVar)); }
+static inline int   Cbs_VarFanin1Value( Gia_Obj_t * pVar )     { return !Cbs_VarIsAssigned(Gia_ObjFanin1(pVar)) ? 2 : (Cbs_VarValue(Gia_ObjFanin1(pVar)) ^ Gia_ObjFaninC1(pVar)); }
+
+#define Cbs_QueForEachEntry( Que, pObj, i )                    \
+    for ( i = (Que).iHead; (i < (Que).iTail) && ((pObj) = (Que).pData[i]); i++ )
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Sets default values of the parameters.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cbs_SetDefaultParams( Cbs_Par_t * pPars )
+{
+    memset( pPars, 0, sizeof(Cbs_Par_t) );
+    pPars->nBTLimit    =  1000;   // limit on the number of conflicts
+    pPars->nJustLimit  =   100;   // limit on the size of justification queue
+    pPars->fUseHighest =     1;   // use node with the highest ID
+    pPars->fUseLowest  =     0;   // use node with the highest ID
+    pPars->fUseMaxFF   =     0;   // use node with the largest fanin fanout
+    pPars->fVerbose    =     1;   // print detailed statistics
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Cbs_Man_t * Cbs_ManAlloc()
+{
+    Cbs_Man_t * p;
+    p = ABC_CALLOC( Cbs_Man_t, 1 );
+    p->pProp.nSize = p->pJust.nSize = 10000;
+    p->pProp.pData = ABC_ALLOC( Gia_Obj_t *, p->pProp.nSize );
+    p->pJust.pData = ABC_ALLOC( Gia_Obj_t *, p->pJust.nSize );
+    p->vModel = Vec_IntAlloc( 1000 );
+    Cbs_SetDefaultParams( &p->Pars );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cbs_ManStop( Cbs_Man_t * p )
+{
+    Vec_IntFree( p->vModel );
+    ABC_FREE( p->pProp.pData );
+    ABC_FREE( p->pJust.pData );
+    ABC_FREE( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns satisfying assignment.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Int_t * Cbs_ReadModel( Cbs_Man_t * p )
+{
+    return p->vModel;
+}
+
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the solver is out of limits.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs_ManCheckLimits( Cbs_Man_t * p )
+{
+    return p->Pars.nJustThis > p->Pars.nJustLimit || p->Pars.nBTThis > p->Pars.nBTLimit;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Saves the satisfying assignment as an array of literals.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs_ManSaveModel( Cbs_Man_t * p, Vec_Int_t * vCex )
+{
+    Gia_Obj_t * pVar;
+    int i;
+    Vec_IntClear( vCex );
+    p->pProp.iHead = 0;
+    Cbs_QueForEachEntry( p->pProp, pVar, i )
+        if ( Gia_ObjIsCi(pVar) )
+            Vec_IntPush( vCex, Gia_Var2Lit(Gia_ObjId(p->pAig,pVar), !Cbs_VarValue(pVar)) );
+} 
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs_QueIsEmpty( Cbs_Que_t * p )
+{
+    return p->iHead == p->iTail;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs_QuePush( Cbs_Que_t * p, Gia_Obj_t * pObj )
+{
+    if ( p->iTail == p->nSize )
+    {
+        p->nSize *= 2;
+        p->pData = ABC_REALLOC( Gia_Obj_t *, p->pData, p->nSize ); 
+    }
+    p->pData[p->iTail++] = pObj;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the object in the queue.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs_QueHasNode( Cbs_Que_t * p, Gia_Obj_t * pObj )
+{
+    Gia_Obj_t * pTemp;
+    int i;
+    Cbs_QueForEachEntry( *p, pTemp, i )
+        if ( pTemp == pObj )
+            return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs_QueStore( Cbs_Que_t * p, int * piHeadOld, int * piTailOld )
+{
+    int i;
+    *piHeadOld = p->iHead;
+    *piTailOld = p->iTail;
+    for ( i = *piHeadOld; i < *piTailOld; i++ )
+        Cbs_QuePush( p, p->pData[i] );
+    p->iHead = *piTailOld;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs_QueRestore( Cbs_Que_t * p, int iHeadOld, int iTailOld )
+{
+    p->iHead = iHeadOld;
+    p->iTail = iTailOld;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Max number of fanins fanouts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs_VarFaninFanoutMax( Cbs_Man_t * p, Gia_Obj_t * pObj )
+{
+    int Count0, Count1;
+    assert( !Gia_IsComplement(pObj) );
+    assert( Gia_ObjIsAnd(pObj) );
+    Count0 = Gia_ObjRefs( p->pAig, Gia_ObjFanin0(pObj) );
+    Count1 = Gia_ObjRefs( p->pAig, Gia_ObjFanin1(pObj) );
+    return ABC_MAX( Count0, Count1 );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find variable with the highest ID.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Gia_Obj_t * Cbs_ManDecideHighest( Cbs_Man_t * p )
+{
+    Gia_Obj_t * pObj, * pObjMax = NULL;
+    int i;
+    Cbs_QueForEachEntry( p->pJust, pObj, i )
+        if ( pObjMax == NULL || pObjMax < pObj )
+            pObjMax = pObj;
+    return pObjMax;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find variable with the lowest ID.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Gia_Obj_t * Cbs_ManDecideLowest( Cbs_Man_t * p )
+{
+    Gia_Obj_t * pObj, * pObjMin = NULL;
+    int i;
+    Cbs_QueForEachEntry( p->pJust, pObj, i )
+        if ( pObjMin == NULL || pObjMin > pObj )
+            pObjMin = pObj;
+    return pObjMin;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Find variable with the maximum number of fanin fanouts.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline Gia_Obj_t * Cbs_ManDecideMaxFF( Cbs_Man_t * p )
+{
+    Gia_Obj_t * pObj, * pObjMax = NULL;
+    int i, iMaxFF = 0, iCurFF;
+    assert( p->pAig->pRefs != NULL );
+    Cbs_QueForEachEntry( p->pJust, pObj, i )
+    {
+        iCurFF = Cbs_VarFaninFanoutMax( p, pObj );
+        assert( iCurFF > 0 );
+        if ( iMaxFF < iCurFF )
+        {
+            iMaxFF = iCurFF;
+            pObjMax = pObj;
+        }
+    }
+    return pObjMax;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs_ManCancelUntil( Cbs_Man_t * p, int iBound )
+{
+    Gia_Obj_t * pVar;
+    int i;
+    assert( iBound <= p->pProp.iTail );
+    p->pProp.iHead = iBound;
+    Cbs_QueForEachEntry( p->pProp, pVar, i )
+        Cbs_VarUnassign( pVar );
+    p->pProp.iTail = iBound;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns the variables a value.]
+
+  Description [Returns 1 if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline void Cbs_ManAssign( Cbs_Man_t * p, Gia_Obj_t * pObj )
+{
+    Gia_Obj_t * pObjR = Gia_Regular(pObj);
+    assert( Gia_ObjIsCand(pObjR) );
+    assert( !Cbs_VarIsAssigned(pObjR) );
+    Cbs_VarAssign( pObjR );
+    Cbs_VarSetValue( pObjR, !Gia_IsComplement(pObj) );
+    Cbs_QuePush( &p->pProp, pObjR );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Propagates a variable.]
+
+  Description [Returns 1 if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs_ManPropagateOne( Cbs_Man_t * p, Gia_Obj_t * pVar )
+{
+    int Value0, Value1;
+    assert( !Gia_IsComplement(pVar) );
+    assert( Cbs_VarIsAssigned(pVar) );
+    if ( Gia_ObjIsCi(pVar) )
+        return 0;
+    assert( Gia_ObjIsAnd(pVar) );
+    Value0 = Cbs_VarFanin0Value(pVar);
+    Value1 = Cbs_VarFanin1Value(pVar);
+    if ( Cbs_VarValue(pVar) )
+    { // value is 1
+        if ( Value0 == 0 || Value1 == 0 ) // one is 0
+            return 1;
+        if ( Value0 == 2 ) // first is unassigned
+            Cbs_ManAssign( p, Gia_ObjChild0(pVar) );
+        if ( Value1 == 2 ) // first is unassigned
+            Cbs_ManAssign( p, Gia_ObjChild1(pVar) );
+        return 0;
+    }
+    // value is 0
+    if ( Value0 == 0 || Value1 == 0 ) // one is 0
+        return 0;
+    if ( Value0 == 1 && Value1 == 1 ) // both are 1
+        return 1;
+    if ( Value0 == 1 || Value1 == 1 ) // one is 1 
+    {
+        if ( Value0 == 2 ) // first is unassigned
+            Cbs_ManAssign( p, Gia_Not(Gia_ObjChild0(pVar)) );
+        if ( Value1 == 2 ) // first is unassigned
+            Cbs_ManAssign( p, Gia_Not(Gia_ObjChild1(pVar)) );
+        return 0;
+    }
+    assert( Cbs_VarIsJust(pVar) );
+    assert( !Cbs_QueHasNode( &p->pJust, pVar ) );
+    Cbs_QuePush( &p->pJust, pVar );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Propagates a variable.]
+
+  Description [Returns 1 if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static inline int Cbs_ManPropagateTwo( Cbs_Man_t * p, Gia_Obj_t * pVar )
+{
+    int Value0, Value1;
+    assert( !Gia_IsComplement(pVar) );
+    assert( Gia_ObjIsAnd(pVar) );
+    assert( Cbs_VarIsAssigned(pVar) );
+    assert( !Cbs_VarValue(pVar) );
+    Value0 = Cbs_VarFanin0Value(pVar);
+    Value1 = Cbs_VarFanin1Value(pVar);
+    // value is 0
+    if ( Value0 == 0 || Value1 == 0 ) // one is 0
+        return 0;
+    if ( Value0 == 1 && Value1 == 1 ) // both are 1
+        return 1;
+    assert( Value0 == 1 || Value1 == 1 );
+    if ( Value0 == 2 ) // first is unassigned
+        Cbs_ManAssign( p, Gia_Not(Gia_ObjChild0(pVar)) );
+    if ( Value1 == 2 ) // first is unassigned
+        Cbs_ManAssign( p, Gia_Not(Gia_ObjChild1(pVar)) );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Propagates all variables.]
+
+  Description [Returns 1 if conflict; 0 if no conflict.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cbs_ManPropagate( Cbs_Man_t * p )
+{
+    Gia_Obj_t * pVar;
+    int i, k;
+    while ( 1 )
+    {
+        Cbs_QueForEachEntry( p->pProp, pVar, i )
+        {
+            if ( Cbs_ManPropagateOne( p, pVar ) )
+                return 1;
+        }
+        p->pProp.iHead = p->pProp.iTail;
+        k = p->pJust.iHead;
+        Cbs_QueForEachEntry( p->pJust, pVar, i )
+        {
+            if ( Cbs_VarIsJust( pVar ) )
+                p->pJust.pData[k++] = pVar;
+            else if ( Cbs_ManPropagateTwo( p, pVar ) )
+                return 1;
+        }
+        if ( k == p->pJust.iTail )
+            break;
+        p->pJust.iTail = k;
+    }
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Solve the problem recursively.]
+
+  Description [Returns 1 if unsat or undecided; 0 if satisfiable.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cbs_ManSolve_rec( Cbs_Man_t * p )
+{
+    Gia_Obj_t * pVar;
+    int iPropHead, iJustHead, iJustTail;
+    // propagate assignments
+    assert( !Cbs_QueIsEmpty(&p->pProp) );
+    if ( Cbs_ManPropagate( p ) )
+        return 1;
+    // check for satisfying assignment
+    assert( Cbs_QueIsEmpty(&p->pProp) );
+    if ( Cbs_QueIsEmpty(&p->pJust) )
+        return 0;
+    // quit using resource limits
+    p->Pars.nBTThis++;
+    p->Pars.nJustThis = ABC_MAX( p->Pars.nJustThis, p->pJust.iTail - p->pJust.iHead );
+    if ( Cbs_ManCheckLimits( p ) )
+        return 1;
+    // remember the state before branching
+    iPropHead = p->pProp.iHead;
+    Cbs_QueStore( &p->pJust, &iJustHead, &iJustTail );
+    // find the decision variable
+    if ( p->Pars.fUseHighest )
+        pVar = Cbs_ManDecideHighest( p );
+    else if ( p->Pars.fUseLowest )
+        pVar = Cbs_ManDecideLowest( p );
+    else if ( p->Pars.fUseMaxFF )
+        pVar = Cbs_ManDecideMaxFF( p );
+    else assert( 0 );
+    assert( Cbs_VarIsJust( pVar ) );
+    // decide using fanout count!
+    if ( Gia_ObjRefs(p->pAig, Gia_ObjFanin0(pVar)) < Gia_ObjRefs(p->pAig, Gia_ObjFanin1(pVar)) )
+    {
+        // decide on first fanin
+        Cbs_ManAssign( p, Gia_Not(Gia_ObjChild0(pVar)) );
+        if ( !Cbs_ManSolve_rec( p ) )
+            return 0;
+        if ( Cbs_ManCheckLimits( p ) )
+            return 1;
+        Cbs_ManCancelUntil( p, iPropHead );
+        Cbs_QueRestore( &p->pJust, iJustHead, iJustTail );
+        // decide on second fanin
+        Cbs_ManAssign( p, Gia_Not(Gia_ObjChild1(pVar)) );
+    }
+    else
+    {
+        // decide on first fanin
+        Cbs_ManAssign( p, Gia_Not(Gia_ObjChild1(pVar)) );
+        if ( !Cbs_ManSolve_rec( p ) )
+            return 0;
+        if ( Cbs_ManCheckLimits( p ) )
+            return 1;
+        Cbs_ManCancelUntil( p, iPropHead );
+        Cbs_QueRestore( &p->pJust, iJustHead, iJustTail );
+        // decide on second fanin
+        Cbs_ManAssign( p, Gia_Not(Gia_ObjChild0(pVar)) );
+    }
+    if ( !Cbs_ManSolve_rec( p ) )
+        return 0;
+    if ( Cbs_ManCheckLimits( p ) )
+        return 1;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Looking for a satisfying assignment of the node.]
+
+  Description [Assumes that each node has flag pObj->fMark0 set to 0.
+  Returns 1 if unsatisfiable, 0 if satisfiable, and -1 if undecided.
+  The node may be complemented. ]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Cbs_ManSolve( Cbs_Man_t * p, Gia_Obj_t * pObj )
+{
+//    Gia_Obj_t * pTemp;
+//    int i;
+    int RetValue;
+//    Gia_ManForEachObj( p->pAig, pTemp, i )
+//        assert( pTemp->fMark0 == 0 );
+    assert( !p->pProp.iHead && !p->pProp.iTail );
+    assert( !p->pJust.iHead && !p->pJust.iTail );
+    p->Pars.nBTThis = p->Pars.nJustThis = 0;
+    Cbs_ManAssign( p, pObj );
+    RetValue = Cbs_ManSolve_rec( p );
+    if ( RetValue == 0 )
+        Cbs_ManSaveModel( p, p->vModel );
+    Cbs_ManCancelUntil( p, 0 );
+    p->pJust.iHead = p->pJust.iTail = 0;
+    p->Pars.nBTTotal += p->Pars.nBTThis;
+    p->Pars.nJustTotal = ABC_MAX( p->Pars.nJustTotal, p->Pars.nJustThis );
+    if ( Cbs_ManCheckLimits( p ) )
+        return -1;
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Procedure to test the new SAT solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Cbs_ManSolveTest( Gia_Man_t * pGia )
+{
+    extern void Gia_SatVerifyPattern( Gia_Man_t * p, Gia_Obj_t * pRoot, Vec_Int_t * vCex, Vec_Int_t * vVisit );
+    int nConfsMax = 1000;
+    int CountUnsat, CountSat, CountUndec;
+    Cbs_Man_t * p; 
+    Vec_Int_t * vCex;
+    Vec_Int_t * vVisit;
+    Gia_Obj_t * pRoot; 
+    int i, RetValue, clk = clock();
+    Gia_ManCreateRefs( pGia );
+    // create logic network
+    p = Cbs_ManAlloc();
+    p->pAig = pGia;
+    // prepare AIG
+    Gia_ManCleanValue( pGia );
+    Gia_ManCleanMark0( pGia );
+    Gia_ManCleanMark1( pGia );
+//    vCex   = Vec_IntAlloc( 100 );
+    vVisit = Vec_IntAlloc( 100 );
+    // solve for each output
+    CountUnsat = CountSat = CountUndec = 0;
+    Gia_ManForEachCo( pGia, pRoot, i )
+    {
+        if ( Gia_ObjIsConst0(Gia_ObjFanin0(pRoot)) )
+            continue;
+
+//        Gia_ManIncrementTravId( pGia );
+
+//printf( "Output %6d : ", i );
+//        iLit = Gia_Var2Lit( Gia_ObjHandle(Gia_ObjFanin0(pRoot)), Gia_ObjFaninC0(pRoot) );
+//        RetValue = Cbs_ManSolve( p, &iLit, 1, nConfsMax, vCex );
+        RetValue = Cbs_ManSolve( p, Gia_ObjChild0(pRoot) );
+        if ( RetValue == 1 )
+            CountUnsat++;
+        else if ( RetValue == -1 )
+            CountUndec++;
+        else 
+        {
+            int iLit, k;
+            vCex = Cbs_ReadModel( p );
+
+//        printf( "complemented = %d.  ", Gia_ObjFaninC0(pRoot) );
+//printf( "conflicts = %6d  max-frontier = %6d \n", p->Pars.nBTThis, p->Pars.nJustThis );
+//            Vec_IntForEachEntry( vCex, iLit, k )
+//                printf( "%s%d ", Gia_LitIsCompl(iLit)? "!": "", Gia_ObjCioId(Gia_ManObj(pGia,Gia_Lit2Var(iLit))) );
+//            printf( "\n" );
+
+            Gia_SatVerifyPattern( pGia, pRoot, vCex, vVisit );
+            assert( RetValue == 0 );
+            CountSat++;
+        }
+//        Gia_ManCheckMark0( p );
+//        Gia_ManCheckMark1( p );
+    }
+    Cbs_ManStop( p );
+//    Vec_IntFree( vCex );
+    Vec_IntFree( vVisit );
+    printf( "Unsat = %d. Sat = %d. Undec = %d.  ", CountUnsat, CountSat, CountUndec );
+    ABC_PRT( "Time", clock() - clk );
+}
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index b5e23856..556828cb 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -3729,8 +3729,8 @@ int Abc_CommandLutmin( Abc_Frame_t * pAbc, int argc, char ** argv )
     pErr = Abc_FrameReadErr(pAbc);
 
     // set defaults
-    nLutSize = 6;
-    fVerbose = 1;
+    nLutSize = 4;
+    fVerbose = 0;
     Extra_UtilGetoptReset();
     while ( ( c = Extra_UtilGetopt( argc, argv, "Kvh" ) ) != EOF )
     {
@@ -3744,8 +3744,6 @@ int Abc_CommandLutmin( Abc_Frame_t * pAbc, int argc, char ** argv )
             }
             nLutSize = atoi(argv[globalUtilOptind]);
             globalUtilOptind++;
-            if ( nLutSize > 1 ) 
-                goto usage;
             break;
         case 'v':
             fVerbose ^= 1;
@@ -23956,6 +23954,7 @@ int Abc_CommandAbc9Test( Abc_Frame_t * pAbc, int argc, char ** argv )
     Gia_Man_t * pTemp = NULL;
     int c, fVerbose = 0;
     extern void Gia_SatSolveTest( Gia_Man_t * p );
+    extern void Cbs_ManSolveTest( Gia_Man_t * pGia );
 
     Extra_UtilGetoptReset();
     while ( ( c = Extra_UtilGetopt( argc, argv, "vh" ) ) != EOF )
@@ -23983,8 +23982,9 @@ int Abc_CommandAbc9Test( Abc_Frame_t * pAbc, int argc, char ** argv )
 //    Gia_SatSolveTest( pAbc->pAig );
 //    For_ManExperiment( pAbc->pAig, 20, 1, 1 );
 //    Gia_ManUnrollSpecial( pAbc->pAig, 5, 100, 1 );
-    pAbc->pAig = Gia_ManDupSelf( pTemp = pAbc->pAig );
-    Gia_ManStop( pTemp );
+//    pAbc->pAig = Gia_ManDupSelf( pTemp = pAbc->pAig );
+//    Gia_ManStop( pTemp );
+//    Cbs_ManSolveTest( pAbc->pAig );
     return 0;
 
 usage:
diff --git a/src/base/abci/abcLut.c b/src/base/abci/abcLut.c
index bb45f6c4..089f4107 100644
--- a/src/base/abci/abcLut.c
+++ b/src/base/abci/abcLut.c
@@ -19,7 +19,7 @@
 ***********************************************************************/
 
 #include "abc.h"
-#include "cut.h"
+#include "cut.h" 
 
 #define LARGE_LEVEL 1000000
 
diff --git a/src/base/abci/abcLutmin.c b/src/base/abci/abcLutmin.c
index 6906e2c4..41ee25fe 100644
--- a/src/base/abci/abcLutmin.c
+++ b/src/base/abci/abcLutmin.c
@@ -20,6 +20,12 @@
 
 #include "abc.h"
 
+/* 
+    Implememented here is the algorithm for minimal-LUT decomposition
+    described in the paper: T. Sasao et al. "On the number of LUTs 
+    to implement logic functions", To appear in Proc. IWLS'09.
+*/
+
 ////////////////////////////////////////////////////////////////////////
 ///                        DECLARATIONS                              ///
 ////////////////////////////////////////////////////////////////////////
@@ -30,6 +36,254 @@
 
 /**Function*************************************************************
 
+  Synopsis    [Implements 2:1 MUX using one 3-LUT.]
+
+  Description [The fanins are (c, d0, d1).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkBddMux21( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pFanins[] )
+{
+    DdManager * dd = pNtkNew->pManFunc;
+    Abc_Obj_t * pNode;
+    DdNode * bSpin, * bCof0, * bCof1;
+    pNode = Abc_NtkCreateNode( pNtkNew );
+    Abc_ObjAddFanin( pNode, pFanins[0] );
+    Abc_ObjAddFanin( pNode, pFanins[1] );
+    Abc_ObjAddFanin( pNode, pFanins[2] );
+    bSpin = Cudd_bddIthVar(dd, 0);
+    bCof0 = Cudd_bddIthVar(dd, 1); 
+    bCof1 = Cudd_bddIthVar(dd, 2); 
+    pNode->pData = Cudd_bddIte( dd, bSpin, bCof1, bCof0 );  Cudd_Ref( pNode->pData ); 
+    return pNode;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements 4:1 MUX using one 6-LUT.]
+
+  Description [The fanins are (c0, c1, d00, d01, d10, d11).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkBddMux411( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pFanins[] )
+{
+    DdManager * dd = pNtkNew->pManFunc;
+    Abc_Obj_t * pNode;
+    DdNode * bSpin, * bCof0, * bCof1;
+    pNode = Abc_NtkCreateNode( pNtkNew );
+    Abc_ObjAddFanin( pNode, pFanins[0] );
+    Abc_ObjAddFanin( pNode, pFanins[1] );
+    Abc_ObjAddFanin( pNode, pFanins[2] );
+    Abc_ObjAddFanin( pNode, pFanins[3] );
+    Abc_ObjAddFanin( pNode, pFanins[4] );
+    Abc_ObjAddFanin( pNode, pFanins[5] );
+    bSpin = Cudd_bddIthVar(dd, 1);
+    bCof0 = Cudd_bddIte( dd, bSpin, Cudd_bddIthVar(dd, 3), Cudd_bddIthVar(dd, 2) ); Cudd_Ref( bCof0 );
+    bCof1 = Cudd_bddIte( dd, bSpin, Cudd_bddIthVar(dd, 5), Cudd_bddIthVar(dd, 4) ); Cudd_Ref( bCof1 );
+    bSpin = Cudd_bddIthVar(dd, 0);
+    pNode->pData = Cudd_bddIte( dd, bSpin, bCof1, bCof0 );  Cudd_Ref( pNode->pData ); 
+    Cudd_RecursiveDeref( dd, bCof0 );
+    Cudd_RecursiveDeref( dd, bCof1 );
+    return pNode;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implementes 4:1 MUX using two 4-LUTs.]
+
+  Description [The fanins are (c0, c1, d00, d01, d10, d11).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkBddMux412( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pFanins[] )
+{
+    DdManager * dd = pNtkNew->pManFunc;
+    Abc_Obj_t * pNodeBot, * pNodeTop;
+    DdNode * bSpin, * bCof0, * bCof1;
+    // bottom node
+    pNodeBot = Abc_NtkCreateNode( pNtkNew );
+    Abc_ObjAddFanin( pNodeBot, pFanins[0] );
+    Abc_ObjAddFanin( pNodeBot, pFanins[1] );
+    Abc_ObjAddFanin( pNodeBot, pFanins[2] );
+    Abc_ObjAddFanin( pNodeBot, pFanins[3] );
+    bSpin = Cudd_bddIthVar(dd, 0);
+    bCof0 = Cudd_bddIte( dd, Cudd_bddIthVar(dd, 1), Cudd_bddIthVar(dd, 3), Cudd_bddIthVar(dd, 2) ); Cudd_Ref( bCof0 );
+    bCof1 = Cudd_bddIthVar(dd, 1);
+    pNodeBot->pData = Cudd_bddIte( dd, bSpin, bCof1, bCof0 );  Cudd_Ref( pNodeBot->pData ); 
+    Cudd_RecursiveDeref( dd, bCof0 );
+    // top node
+    pNodeTop = Abc_NtkCreateNode( pNtkNew );
+    Abc_ObjAddFanin( pNodeTop, pFanins[0] );
+    Abc_ObjAddFanin( pNodeTop, pNodeBot   );
+    Abc_ObjAddFanin( pNodeTop, pFanins[4] );
+    Abc_ObjAddFanin( pNodeTop, pFanins[5] );
+    bSpin = Cudd_bddIthVar(dd, 0);
+    bCof0 = Cudd_bddIthVar(dd, 1);
+    bCof1 = Cudd_bddIte( dd, Cudd_bddIthVar(dd, 1), Cudd_bddIthVar(dd, 3), Cudd_bddIthVar(dd, 2) ); Cudd_Ref( bCof1 );
+    pNodeTop->pData = Cudd_bddIte( dd, bSpin, bCof1, bCof0 );  Cudd_Ref( pNodeTop->pData ); 
+    Cudd_RecursiveDeref( dd, bCof1 );
+    return pNodeTop;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implementes 4:1 MUX using two 4-LUTs.]
+
+  Description [The fanins are (c0, c1, d00, d01, d10, d11).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkBddMux412a( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pFanins[] )
+{
+    DdManager * dd = pNtkNew->pManFunc;
+    Abc_Obj_t * pNodeBot, * pNodeTop;
+    DdNode * bSpin, * bCof0, * bCof1;
+    // bottom node
+    pNodeBot = Abc_NtkCreateNode( pNtkNew );
+    Abc_ObjAddFanin( pNodeBot, pFanins[1] );
+    Abc_ObjAddFanin( pNodeBot, pFanins[2] );
+    Abc_ObjAddFanin( pNodeBot, pFanins[3] );
+    bSpin = Cudd_bddIthVar(dd, 0);
+    bCof0 = Cudd_bddIthVar(dd, 1);
+    bCof1 = Cudd_bddIthVar(dd, 2);
+    pNodeBot->pData = Cudd_bddIte( dd, bSpin, bCof1, bCof0 );  Cudd_Ref( pNodeBot->pData ); 
+    // top node
+    pNodeTop = Abc_NtkCreateNode( pNtkNew );
+    Abc_ObjAddFanin( pNodeTop, pFanins[0] );
+    Abc_ObjAddFanin( pNodeTop, pFanins[1] );
+    Abc_ObjAddFanin( pNodeTop, pNodeBot   );
+    Abc_ObjAddFanin( pNodeTop, pFanins[4] );
+    Abc_ObjAddFanin( pNodeTop, pFanins[5] );
+    bSpin = Cudd_bddIthVar(dd, 0);
+    bCof0 = Cudd_bddIthVar(dd, 2);
+    bCof1 = Cudd_bddIte( dd, Cudd_bddIthVar(dd, 1), Cudd_bddIthVar(dd, 4), Cudd_bddIthVar(dd, 3) ); Cudd_Ref( bCof1 );
+    pNodeTop->pData = Cudd_bddIte( dd, bSpin, bCof1, bCof0 );  Cudd_Ref( pNodeTop->pData ); 
+    Cudd_RecursiveDeref( dd, bCof1 );
+    return pNodeTop;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Implements 4:1 MUX using three 2:1 MUXes.]
+
+  Description [The fanins are (c0, c1, d00, d01, d10, d11).]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkBddMux413( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pFanins[] )
+{
+    Abc_Obj_t * pNodesBot[3], * pNodesTop[3];
+    // left bottom
+    pNodesBot[0] = pFanins[1];
+    pNodesBot[1] = pFanins[2];
+    pNodesBot[2] = pFanins[3];
+    pNodesTop[1] = Abc_NtkBddMux21( pNtkNew, pNodesBot );
+    // right bottom
+    pNodesBot[0] = pFanins[1];
+    pNodesBot[1] = pFanins[4];
+    pNodesBot[2] = pFanins[5];
+    pNodesTop[2] = Abc_NtkBddMux21( pNtkNew, pNodesBot );
+    // top node
+    pNodesTop[0] = pFanins[0];
+    return Abc_NtkBddMux21( pNtkNew, pNodesTop );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finds unique cofactors of the function on the given level.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+DdNode * Abc_NtkBddCofactors_rec( DdManager * dd, DdNode * bNode, int iCof, int iLevel, int nLevels )
+{
+    DdNode * bNode0, * bNode1;
+    if ( Cudd_IsConstant(bNode) || iLevel == nLevels )
+        return bNode;
+    if ( Cudd_ReadPerm( dd, Cudd_NodeReadIndex(bNode) ) > iLevel )
+    {
+        bNode0 = bNode;
+        bNode1 = bNode;
+    }
+    else if ( Cudd_IsComplement(bNode) )
+    {
+        bNode0 = Cudd_Not(cuddE(Cudd_Regular(bNode)));
+        bNode1 = Cudd_Not(cuddT(Cudd_Regular(bNode)));
+    }
+    else
+    {
+        bNode0 = cuddE(bNode);
+        bNode1 = cuddT(bNode);
+    }
+    if ( (iCof >> (nLevels-1-iLevel)) & 1 )
+        return Abc_NtkBddCofactors_rec( dd, bNode1, iCof, iLevel + 1, nLevels );
+    return Abc_NtkBddCofactors_rec( dd, bNode0, iCof, iLevel + 1, nLevels );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Finds unique cofactors of the function on the given level.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Abc_NtkBddCofactors( DdManager * dd, DdNode * bNode, int Level )
+{
+    Vec_Ptr_t * vCofs;
+    int i, nCofs = (1<<Level);
+    assert( Level > 0 && Level < 10 );
+    vCofs = Vec_PtrAlloc( 8 );
+    for ( i = 0; i < nCofs; i++ )
+        Vec_PtrPush( vCofs, Abc_NtkBddCofactors_rec( dd, bNode, i, 0, Level ) );
+    return vCofs;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Comparison procedure for two integers.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+static int Vec_PtrSortCompare( void ** pp1, void ** pp2 )
+{
+    if ( *pp1 < *pp2 )
+        return -1;
+    if ( *pp1 > *pp2 )
+        return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
   Synopsis    [Converts the node to MUXes.]
 
   Description []
@@ -39,27 +293,43 @@
   SeeAlso     []
 
 ***********************************************************************/
-Abc_Obj_t * Abc_NtkCreateNodeLut( Abc_Ntk_t * pNtkNew, DdManager * dd, DdNode * bFunc, Abc_Obj_t * pNode, int nLutSize )
+Abc_Obj_t * Abc_NtkCreateCofLut( Abc_Ntk_t * pNtkNew, DdManager * dd, DdNode * bCof, Abc_Obj_t * pNode, int Level )
 {
+    int fVerbose = 0;
     DdNode * bFuncNew;
     Abc_Obj_t * pNodeNew;
-    int i, nStart = ABC_MIN( 0, Abc_ObjFaninNum(pNode) - nLutSize );
+    int i;
+    assert( Abc_ObjFaninNum(pNode) > Level );
     // create a new node
     pNodeNew = Abc_NtkCreateNode( pNtkNew );
     // add the fanins in the order, in which they appear in the reordered manager
-    for ( i = nStart; i < Abc_ObjFaninNum(pNode); i++ )
+    for ( i = Level; i < Abc_ObjFaninNum(pNode); i++ )
         Abc_ObjAddFanin( pNodeNew, Abc_ObjFanin(pNode, i)->pCopy );
+if ( fVerbose )
+{
+Extra_bddPrint( dd, bCof );
+printf( "\n" );
+printf( "\n" );
+}
     // transfer the function
-    bFuncNew = Extra_bddMove( dd, bFunc, nStart );  Cudd_Ref( bFuncNew );
-    assert( Cudd_SupportSize(dd, bFuncNew) <= nLutSize );
+    bFuncNew = Extra_bddMove( dd, bCof, -Level );  Cudd_Ref( bFuncNew );
+if ( fVerbose )
+{
+Extra_bddPrint( dd, bFuncNew );
+printf( "\n" );
+printf( "\n" );
+}
     pNodeNew->pData = Extra_TransferLevelByLevel( dd, pNtkNew->pManFunc, bFuncNew );  Cudd_Ref( pNodeNew->pData );
+//Extra_bddPrint( pNtkNew->pManFunc, pNodeNew->pData );
+//printf( "\n" );
+//printf( "\n" );
     Cudd_RecursiveDeref( dd, bFuncNew );
     return pNodeNew;
 }
 
 /**Function*************************************************************
 
-  Synopsis    [Converts the node to MUXes.]
+  Synopsis    [Performs one step of Ashenhurst-Curtis decomposition.]
 
   Description []
                
@@ -68,36 +338,164 @@ Abc_Obj_t * Abc_NtkCreateNodeLut( Abc_Ntk_t * pNtkNew, DdManager * dd, DdNode *
   SeeAlso     []
 
 ***********************************************************************/
-Abc_Obj_t * Abc_NodeBddToMuxesLut_rec( DdManager * dd, DdNode * bFunc, Abc_Ntk_t * pNtkNew, st_table * tBdd2Node, Abc_Obj_t * pNode, int nLutSize )
-{
-    Abc_Obj_t * pNodeNew, * pNodeNew0, * pNodeNew1, * pNodeNewC;
-    assert( !Cudd_IsComplement(bFunc) );
-    if ( bFunc == b1 )
-        return Abc_NtkCreateNodeConst1(pNtkNew);
-    if ( st_lookup( tBdd2Node, (char *)bFunc, (char **)&pNodeNew ) )
-        return pNodeNew;
-    if ( dd->perm[bFunc->index] >= Abc_ObjFaninNum(pNode) - nLutSize )
-    {
-        pNodeNew = Abc_NtkCreateNodeLut( pNtkNew, dd, bFunc, pNode, nLutSize );
-        st_insert( tBdd2Node, (char *)bFunc, (char *)pNodeNew );
-        return pNodeNew;
-    }
-    // solve for the children nodes
-    pNodeNew0 = Abc_NodeBddToMuxesLut_rec( dd, Cudd_Regular(cuddE(bFunc)), pNtkNew, tBdd2Node, pNode, nLutSize );
-    if ( Cudd_IsComplement(cuddE(bFunc)) )
-        pNodeNew0 = Abc_NtkCreateNodeInv( pNtkNew, pNodeNew0 );
-    pNodeNew1 = Abc_NodeBddToMuxesLut_rec( dd, cuddT(bFunc), pNtkNew, tBdd2Node, pNode, nLutSize );
-    if ( !st_lookup( tBdd2Node, (char *)Cudd_bddIthVar(dd, bFunc->index), (char **)&pNodeNewC ) )
-        assert( 0 );
-    // create the MUX node
-    pNodeNew = Abc_NtkCreateNodeMux( pNtkNew, pNodeNewC, pNodeNew1, pNodeNew0 );
-    st_insert( tBdd2Node, (char *)bFunc, (char *)pNodeNew );
+Abc_Obj_t * Abc_NtkBddCurtis( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNode, Vec_Ptr_t * vCofs, Vec_Ptr_t * vUniq )
+{
+    DdManager * ddOld = pNode->pNtk->pManFunc;
+    DdManager * ddNew = pNtkNew->pManFunc;
+    DdNode * bCof, * bUniq, * bMint, * bTemp, * bFunc, * bBits[10], ** pbCodeVars;
+    Abc_Obj_t * pNodeNew = NULL, * pNodeBS[10];
+    int nLutSize = Extra_Base2Log( Vec_PtrSize(vCofs) );
+    int nBits    = Extra_Base2Log( Vec_PtrSize(vUniq) );
+    int b, c, u, i;
+    assert( nBits + 2 <= nLutSize );
+    assert( nLutSize < Abc_ObjFaninNum(pNode) );
+    // start BDDs for the decompoosed blocks
+    for ( b = 0; b < nBits; b++ )
+        bBits[b] = Cudd_ReadLogicZero(ddNew), Cudd_Ref( bBits[b] );
+    // add each bound set minterm to one of the blccks
+    Vec_PtrForEachEntry( vCofs, bCof, c )
+    {
+        Vec_PtrForEachEntry( vUniq, bUniq, u )
+            if ( bUniq == bCof )
+                break;
+        assert( u < Vec_PtrSize(vUniq) );
+        for ( b = 0; b < nBits; b++ )
+        {
+            if ( ((u >> b) & 1) == 0 )
+                continue;
+            bMint = Extra_bddBitsToCube( ddNew, c, nLutSize, ddNew->vars, 1 );  Cudd_Ref( bMint );
+            bBits[b] = Cudd_bddOr( ddNew, bTemp = bBits[b], bMint );  Cudd_Ref( bBits[b] );
+            Cudd_RecursiveDeref( ddNew, bTemp );
+            Cudd_RecursiveDeref( ddNew, bMint );
+        }
+    }
+    // create bound set nodes
+    for ( b = 0; b < nBits; b++ )
+    {
+        pNodeBS[b] = Abc_NtkCreateNode( pNtkNew );
+        for ( i = 0; i < nLutSize; i++ )
+            Abc_ObjAddFanin( pNodeBS[b], Abc_ObjFanin(pNode, i)->pCopy );
+        pNodeBS[b]->pData = bBits[b]; // takes ref
+    }
+    // create composition node
+    pNodeNew = Abc_NtkCreateNode( pNtkNew );
+    // add free set variables first
+    for ( i = nLutSize; i < Abc_ObjFaninNum(pNode); i++ )
+        Abc_ObjAddFanin( pNodeNew, Abc_ObjFanin(pNode, i)->pCopy );
+    // add code bit variables next
+    for ( b = 0; b < nBits; b++ )
+        Abc_ObjAddFanin( pNodeNew, pNodeBS[b] );
+    // derive function of the composition node
+    bFunc = Cudd_ReadLogicZero(ddNew); Cudd_Ref( bFunc );
+    pbCodeVars = ddNew->vars + Abc_ObjFaninNum(pNode) - nLutSize;
+    Vec_PtrForEachEntry( vUniq, bUniq, u )
+    {
+        bUniq = Extra_bddMove( ddOld, bUniq, -nLutSize );                   Cudd_Ref( bUniq );
+        bUniq = Extra_TransferLevelByLevel( ddOld, ddNew, bTemp = bUniq );  Cudd_Ref( bUniq );
+        Cudd_RecursiveDeref( ddOld, bTemp );
+
+        bMint = Extra_bddBitsToCube( ddNew, u, nBits, pbCodeVars, 0 );  Cudd_Ref( bMint );
+        bMint = Cudd_bddAnd( ddNew, bTemp = bMint, bUniq );  Cudd_Ref( bMint );
+        Cudd_RecursiveDeref( ddNew, bTemp );
+        Cudd_RecursiveDeref( ddNew, bUniq );
+
+        bFunc = Cudd_bddOr( ddNew, bTemp = bFunc, bMint );  Cudd_Ref( bFunc );
+        Cudd_RecursiveDeref( ddNew, bTemp );
+        Cudd_RecursiveDeref( ddNew, bMint );
+    }
+    pNodeNew->pData = bFunc; // takes ref
     return pNodeNew;
 }
 
 /**Function*************************************************************
 
-  Synopsis    [Converts the node to MUXes.]
+  Synopsis    [Tries to decompose using cofactoring into two LUTs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkBddFindCofactor( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNode, int nLutSize )
+{
+    Abc_Obj_t * pNodeBot, * pNodeTop;
+    DdManager * ddOld = pNode->pNtk->pManFunc;
+    DdManager * ddNew = pNtkNew->pManFunc;
+    DdNode * bCof0, * bCof1, * bSupp, * bTemp, * bVar;
+    DdNode * bCof0n, * bCof1n;
+    int i, iCof, iFreeVar, fCof1Smaller = -1;
+    assert( Abc_ObjFaninNum(pNode) == nLutSize + 1 );
+    for ( iCof = 0; iCof < Abc_ObjFaninNum(pNode); iCof++ )
+    {
+        bVar  = Cudd_bddIthVar( ddOld, iCof );
+        bCof0 = Cudd_Cofactor( ddOld, pNode->pData, Cudd_Not(bVar) );  Cudd_Ref( bCof0 );
+        bCof1 = Cudd_Cofactor( ddOld, pNode->pData, bVar  );           Cudd_Ref( bCof1 );
+        if ( Cudd_SupportSize( ddOld, bCof0 ) <= nLutSize - 2 )
+        {
+            fCof1Smaller = 0;
+            break;
+        }
+        if ( Cudd_SupportSize( ddOld, bCof1 ) <= nLutSize - 2 )
+        {
+            fCof1Smaller = 1;
+            break;
+        }
+        Cudd_RecursiveDeref( ddOld, bCof0 );
+        Cudd_RecursiveDeref( ddOld, bCof1 );
+    }
+    if ( iCof == Abc_ObjFaninNum(pNode) )
+        return NULL;
+    // find unused variable
+    bSupp = Cudd_Support( ddOld, fCof1Smaller? bCof1 : bCof0 );   Cudd_Ref( bSupp );
+    iFreeVar = -1;
+    for ( i = 0; i < Abc_ObjFaninNum(pNode); i++ )
+    {
+        assert( i == Cudd_ReadPerm(ddOld, i) );
+        if ( i == iCof )
+            continue;
+        for ( bTemp = bSupp; !Cudd_IsConstant(bTemp); bTemp = cuddT(bTemp) )
+            if ( i == (int)Cudd_NodeReadIndex(bTemp) )
+                break;
+        if ( Cudd_IsConstant(bTemp) )
+        {
+            iFreeVar = i;
+            break;
+        }
+    }
+    assert( iFreeVar != iCof && iFreeVar < Abc_ObjFaninNum(pNode) );
+    Cudd_RecursiveDeref( ddOld, bSupp );
+    // transfer the cofactors
+    bCof0n = Extra_TransferLevelByLevel( ddOld, ddNew, bCof0 ); Cudd_Ref( bCof0n );
+    bCof1n = Extra_TransferLevelByLevel( ddOld, ddNew, bCof1 ); Cudd_Ref( bCof1n );
+    Cudd_RecursiveDeref( ddOld, bCof0 );
+    Cudd_RecursiveDeref( ddOld, bCof1 );
+    // create bottom node
+    pNodeBot = Abc_NtkCreateNode( pNtkNew );
+    for ( i = 0; i < Abc_ObjFaninNum(pNode); i++ )
+        Abc_ObjAddFanin( pNodeBot, Abc_ObjFanin(pNode, i)->pCopy );
+    pNodeBot->pData = fCof1Smaller? bCof0n : bCof1n;
+    // create top node
+    pNodeTop = Abc_NtkCreateNode( pNtkNew );
+    for ( i = 0; i < Abc_ObjFaninNum(pNode); i++ )
+        if ( i == iFreeVar )           
+            Abc_ObjAddFanin( pNodeTop, pNodeBot );
+        else
+            Abc_ObjAddFanin( pNodeTop, Abc_ObjFanin(pNode, i)->pCopy );
+    // derive the new function
+    pNodeTop->pData = Cudd_bddIte( ddNew, 
+        Cudd_bddIthVar(ddNew, iCof), 
+        fCof1Smaller? bCof1n : Cudd_bddIthVar(ddNew, iFreeVar), 
+        fCof1Smaller? Cudd_bddIthVar(ddNew, iFreeVar) : bCof0n );
+    Cudd_Ref( pNodeTop->pData );
+    Cudd_RecursiveDeref( ddNew, fCof1Smaller? bCof1n : bCof0n );
+    return pNodeTop;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Decompose the function once.]
 
   Description []
                
@@ -106,23 +504,64 @@ Abc_Obj_t * Abc_NodeBddToMuxesLut_rec( DdManager * dd, DdNode * bFunc, Abc_Ntk_t
   SeeAlso     []
 
 ***********************************************************************/
-Abc_Obj_t * Abc_NodeBddToMuxesLut( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNodeOld, int nLutSize )
+Abc_Obj_t * Abc_NtkBddDecompose( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNode, int nLutSize, int fVerbose )
 {
-    DdManager * dd = pNodeOld->pNtk->pManFunc;
-    DdNode * bFunc = pNodeOld->pData;
-    Abc_Obj_t * pFaninOld, * pNodeNew;
-    st_table * tBdd2Node;
+    Vec_Ptr_t * vCofs, * vUniq;
+    DdManager * dd = pNode->pNtk->pManFunc;
+    DdNode * bCof;
+    Abc_Obj_t * pNodeNew = NULL;
+    Abc_Obj_t * pCofs[20];
     int i;
-    // create the table mapping BDD nodes into the ABC nodes
-    tBdd2Node = st_init_table( st_ptrcmp, st_ptrhash );
-    // add the constant and the elementary vars
-    Abc_ObjForEachFanin( pNodeOld, pFaninOld, i )
-        st_insert( tBdd2Node, (char *)Cudd_bddIthVar(dd, i), (char *)pFaninOld->pCopy );
-    // create the new nodes recursively
-    pNodeNew = Abc_NodeBddToMuxesLut_rec( dd, Cudd_Regular(bFunc), pNtkNew, tBdd2Node, pNodeOld, nLutSize );
-    st_free_table( tBdd2Node );
-    if ( Cudd_IsComplement(bFunc) )
-        pNodeNew = Abc_NtkCreateNodeInv( pNtkNew, pNodeNew );
+    assert( Abc_ObjFaninNum(pNode) > nLutSize );
+    // try to decompose with two LUTs (the best case for Supp = LutSize + 1)
+    if ( Abc_ObjFaninNum(pNode) == nLutSize + 1 )
+    {
+
+        pNodeNew = Abc_NtkBddFindCofactor( pNtkNew, pNode, nLutSize );
+        if ( pNodeNew != NULL )
+        {
+            if ( fVerbose )
+            printf( "Decomposing %d-input node %d using MUX.\n",
+                Abc_ObjFaninNum(pNode), Abc_ObjId(pNode) );
+            return pNodeNew;
+        }
+
+    }
+    // cofactor w.r.t. the bound set variables
+    vCofs = Abc_NtkBddCofactors( dd, pNode->pData, nLutSize );
+    vUniq = Vec_PtrDup( vCofs );
+    Vec_PtrUniqify( vUniq, (int (*)())Vec_PtrSortCompare );
+    // only perform decomposition with it is support reduring with two less vars
+    if( Vec_PtrSize(vUniq) > (1 << (nLutSize-2)) )
+    {
+        Vec_PtrFree( vCofs );
+        vCofs = Abc_NtkBddCofactors( dd, pNode->pData, 2 );
+        if ( fVerbose )
+        printf( "Decomposing %d-input node %d using cofactoring with %d cofactors.\n",
+            Abc_ObjFaninNum(pNode), Abc_ObjId(pNode), Vec_PtrSize(vCofs) );
+        // implement the cofactors
+        pCofs[0] = Abc_ObjFanin(pNode, 0)->pCopy;
+        pCofs[1] = Abc_ObjFanin(pNode, 1)->pCopy;
+        Vec_PtrForEachEntry( vCofs, bCof, i )
+            pCofs[2+i] = Abc_NtkCreateCofLut( pNtkNew, dd, bCof, pNode, 2 );
+        if ( nLutSize == 4 )
+            pNodeNew = Abc_NtkBddMux412( pNtkNew, pCofs );
+        else if ( nLutSize == 5 )
+            pNodeNew = Abc_NtkBddMux412a( pNtkNew, pCofs );
+        else if ( nLutSize == 6 )
+            pNodeNew = Abc_NtkBddMux411( pNtkNew, pCofs );
+        else  assert( 0 );
+    }
+    // alternative decompose using MUX-decomposition
+    else
+    {
+        if ( fVerbose )
+        printf( "Decomposing %d-input node %d using Curtis with %d unique columns.\n",
+            Abc_ObjFaninNum(pNode), Abc_ObjId(pNode), Vec_PtrSize(vUniq) );
+        pNodeNew = Abc_NtkBddCurtis( pNtkNew, pNode, vCofs, vUniq );
+    }
+    Vec_PtrFree( vCofs );
+    Vec_PtrFree( vUniq );
     return pNodeNew;
 }
 
@@ -137,20 +576,24 @@ Abc_Obj_t * Abc_NodeBddToMuxesLut( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNodeOld, in
   SeeAlso     []
 
 ***********************************************************************/
-void Abc_NtkLutminConstruct( Abc_Ntk_t * pNtkClp, Abc_Ntk_t * pNtkDec, int nLutSize )
+void Abc_NtkLutminConstruct( Abc_Ntk_t * pNtkClp, Abc_Ntk_t * pNtkDec, int nLutSize, int fVerbose )
 {
-    Abc_Obj_t * pObj, * pDriver;
-    int i;
-    Abc_NtkForEachCo( pNtkClp, pObj, i )
+    Vec_Ptr_t * vNodes;
+    Abc_Obj_t * pNode, * pFanin;
+    int i, k;
+    vNodes = Abc_NtkDfs( pNtkClp, 0 );
+    Vec_PtrForEachEntry( vNodes, pNode, i )
     {
-        pDriver = Abc_ObjFanin0( pObj );
-        if ( !Abc_ObjIsNode(pDriver) )
-            continue;
-        if ( Abc_ObjFaninNum(pDriver) == 0 )
-            pDriver->pCopy = Abc_NtkDupObj( pNtkDec, pDriver, 0 );
+        if ( Abc_ObjFaninNum(pNode) <= nLutSize )
+        {
+            pNode->pCopy = Abc_NtkDupObj( pNtkDec, pNode, 0 );
+            Abc_ObjForEachFanin( pNode, pFanin, k )
+                Abc_ObjAddFanin( pNode->pCopy, pFanin->pCopy );
+        }
         else
-            pDriver->pCopy = Abc_NodeBddToMuxesLut( pNtkDec, pDriver, nLutSize );
+            pNode->pCopy = Abc_NtkBddDecompose( pNtkDec, pNode, nLutSize, fVerbose );
     }
+    Vec_PtrFree( vNodes );
 }
 
 /**Function*************************************************************
@@ -164,42 +607,87 @@ void Abc_NtkLutminConstruct( Abc_Ntk_t * pNtkClp, Abc_Ntk_t * pNtkDec, int nLutS
   SeeAlso     []
 
 ***********************************************************************/
-Abc_Ntk_t * Abc_NtkLutmin( Abc_Ntk_t * pNtk, int nLutSize, int fVerbose )
+Abc_Ntk_t * Abc_NtkLutminInt( Abc_Ntk_t * pNtk, int nLutSize, int fVerbose )
 {
     extern void Abc_NtkBddReorder( Abc_Ntk_t * pNtk, int fVerbose );
-    Abc_Ntk_t * pNtkDec, * pNtkClp, * pTemp;
-    // collapse the network and reorder BDDs
-    if ( Abc_NtkIsStrash(pNtk) )
-        pTemp = Abc_NtkDup( pNtk );
-    else
-        pTemp = Abc_NtkStrash( pNtk, 0, 1, 0 );
-    pNtkClp = Abc_NtkCollapse( pTemp, 10000, 0, 1, 0 );
-    Abc_NtkDelete( pTemp );
-    if ( pNtkClp == NULL )
-        return NULL;
-    if ( !Abc_NtkIsBddLogic(pNtkClp) )
-        Abc_NtkToBdd( pNtkClp );
-    Abc_NtkBddReorder( pNtkClp, fVerbose );
+    Abc_Ntk_t * pNtkDec;
+    // minimize BDDs
+//    Abc_NtkBddReorder( pNtk, fVerbose );
+    Abc_NtkBddReorder( pNtk, 0 );
     // decompose one output at a time
-    pNtkDec = Abc_NtkStartFrom( pNtkClp, ABC_NTK_LOGIC, ABC_FUNC_BDD );
+    pNtkDec = Abc_NtkStartFrom( pNtk, ABC_NTK_LOGIC, ABC_FUNC_BDD );
     // make sure the new manager has enough inputs
-    Cudd_bddIthVar( pNtkDec->pManFunc, nLutSize );
+    Cudd_bddIthVar( pNtkDec->pManFunc, Abc_NtkGetFaninMax(pNtk) );
     // put the results into the new network (save new CO drivers in old CO drivers)
-    Abc_NtkLutminConstruct( pNtkClp, pNtkDec, nLutSize );
+    Abc_NtkLutminConstruct( pNtk, pNtkDec, nLutSize, fVerbose );
     // finalize the new network
-    Abc_NtkFinalize( pNtkClp, pNtkDec );
-    Abc_NtkDelete( pNtkClp );
+    Abc_NtkFinalize( pNtk, pNtkDec );
     // make the network minimum base
     Abc_NtkMinimumBase( pNtkDec );
+    return pNtkDec;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs minimum-LUT decomposition of the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Abc_NtkLutmin( Abc_Ntk_t * pNtkInit, int nLutSize, int fVerbose )
+{
+    extern bool Abc_NtkFraigSweep( Abc_Ntk_t * pNtk, int fUseInv, int fExdc, int fVerbose, int fVeryVerbose );
+    Abc_Ntk_t * pNtkNew, * pTemp;
+    int i;
+    if ( nLutSize < 4 )
+    {
+        printf( "The LUT count (%d) should be at least 4.\n", nLutSize );
+        return NULL;
+    }
+    if ( nLutSize > 6 )
+    {
+        printf( "The LUT count (%d) should not exceed 6.\n", nLutSize );
+        return NULL;
+    }
+    // create internal representation
+    if ( Abc_NtkIsStrash(pNtkInit) )
+        pNtkNew = Abc_NtkDup( pNtkInit );
+    else
+        pNtkNew = Abc_NtkStrash( pNtkInit, 0, 1, 0 );
+    // collapse the network 
+    pNtkNew = Abc_NtkCollapse( pTemp = pNtkNew, 10000, 0, 1, 0 );
+    Abc_NtkDelete( pTemp );
+    if ( pNtkNew == NULL )
+        return NULL;
+    // convert it to BDD
+    if ( !Abc_NtkIsBddLogic(pNtkNew) )
+        Abc_NtkToBdd( pNtkNew );
+    // iterate decomposition
+    for ( i = 0; Abc_NtkGetFaninMax(pNtkNew) > nLutSize; i++ )
+    {
+        if ( fVerbose )
+            printf( "*** Iteration %d:\n", i+1 );
+        if ( fVerbose )
+            printf( "Decomposing network with %d nodes and %d max fanin count for K = %d.\n", 
+                Abc_NtkNodeNum(pNtkNew), Abc_NtkGetFaninMax(pNtkNew), nLutSize );
+        pNtkNew = Abc_NtkLutminInt( pTemp = pNtkNew, nLutSize, fVerbose );
+        Abc_NtkDelete( pTemp );
+    }
     // fix the problem with complemented and duplicated CO edges
-    Abc_NtkLogicMakeSimpleCos( pNtkDec, 0 );
+    Abc_NtkLogicMakeSimpleCos( pNtkNew, 0 );
+    // merge functionally equivalent nodes
+    Abc_NtkFraigSweep( pNtkNew, 1, 0, 0, 0 );
     // make sure everything is okay
-    if ( !Abc_NtkCheck( pNtkDec ) )
+    if ( !Abc_NtkCheck( pNtkNew ) )
     {
         printf( "Abc_NtkLutmin: The network check has failed.\n" );
         return 0;
     }
-    return pNtkDec;
+    return pNtkNew;
 }
 
 ////////////////////////////////////////////////////////////////////////
diff --git a/src/misc/extra/extra.h b/src/misc/extra/extra.h
index f81479b3..dc2c2b0b 100644
--- a/src/misc/extra/extra.h
+++ b/src/misc/extra/extra.h
@@ -169,7 +169,7 @@ extern DdNode *    Extra_bddImageRead2( Extra_ImageTree2_t * pTree );
 extern DdNode *     Extra_TransferPermute( DdManager * ddSource, DdManager * ddDestination, DdNode * f, int * Permute );
 extern DdNode *     Extra_TransferLevelByLevel( DdManager * ddSource, DdManager * ddDestination, DdNode * f );
 extern DdNode *     Extra_bddRemapUp( DdManager * dd, DdNode * bF );
-extern DdNode *     Extra_bddMove( DdManager * dd, DdNode * bF, int fShiftUp );
+extern DdNode *     Extra_bddMove( DdManager * dd, DdNode * bF, int nVars );
 extern DdNode *     extraBddMove( DdManager * dd, DdNode * bF, DdNode * bFlag );
 extern void         Extra_StopManager( DdManager * dd );
 extern void         Extra_bddPrint( DdManager * dd, DdNode * F );
diff --git a/src/misc/extra/extraBddMisc.c b/src/misc/extra/extraBddMisc.c
index e17d1744..0c285fc7 100644
--- a/src/misc/extra/extraBddMisc.c
+++ b/src/misc/extra/extraBddMisc.c
@@ -221,6 +221,7 @@ void Extra_StopManager( DdManager * dd )
     // check for remaining references in the package
     RetValue = Cudd_CheckZeroRef( dd );
     if ( RetValue > 10 )
+//    if ( RetValue )
         printf( "\nThe number of referenced nodes = %d\n\n", RetValue );
 //  Cudd_PrintInfo( dd, stdout );
     Cudd_Quit( dd );
diff --git a/src/opt/mfs/mfsSat.c b/src/opt/mfs/mfsSat.c
index a35d67e4..eab80c53 100644
--- a/src/opt/mfs/mfsSat.c
+++ b/src/opt/mfs/mfsSat.c
@@ -43,11 +43,16 @@ int Abc_NtkMfsSolveSat_iter( Mfs_Man_t * p )
 {
     int Lits[MFS_FANIN_MAX];
     int RetValue, nBTLimit, iVar, b, Mint;
+//    int nConfs = p->pSat->stats.conflicts;
     if ( p->nTotConfLim && p->nTotConfLim <= p->pSat->stats.conflicts )
         return -1;
     nBTLimit = p->nTotConfLim? p->nTotConfLim - p->pSat->stats.conflicts : 0;
     RetValue = sat_solver_solve( p->pSat, NULL, NULL, (ABC_INT64_T)nBTLimit, (ABC_INT64_T)0, (ABC_INT64_T)0, (ABC_INT64_T)0 );
     assert( RetValue == l_Undef || RetValue == l_True || RetValue == l_False );
+//printf( "%c", RetValue==l_Undef ? '?' : (RetValue==l_False ? '-' : '+') );
+//printf( "%d ", p->pSat->stats.conflicts-nConfs );
+//if ( RetValue==l_False )
+//printf( "\n" );
     if ( RetValue == l_Undef )
         return -1;
     if ( RetValue == l_False )