Version abc80909

22 files changed, 1501 insertions, 72 deletions

diff --git a/src/aig/aig/aigPartReg.c b/src/aig/aig/aigPartReg.c
index 79761a41..6baeae31 100644
--- a/src/aig/aig/aigPartReg.c
+++ b/src/aig/aig/aigPartReg.c
@@ -19,7 +19,7 @@
 ***********************************************************************/
 
 #include "aig.h"
-#include "fra.h"
+//#include "fra.h"
 
 ////////////////////////////////////////////////////////////////////////
 ///                        DECLARATIONS                              ///
diff --git a/src/aig/aig/aigPartSat.c b/src/aig/aig/aigPartSat.c
index 2a3e975c..15aa1a05 100644
--- a/src/aig/aig/aigPartSat.c
+++ b/src/aig/aig/aigPartSat.c
@@ -494,7 +494,7 @@ int Aig_ManPartitionedSat( Aig_Man_t * p, int nAlgo, int nPartSize,
     Aig_Man_t * pAig, * pTemp;
     Vec_Int_t * vNode2Part, * vNode2Var;
     int nConfRemaining = nConfTotal, nNodes = 0;
-    int i, clk, status, RetValue;
+    int i, clk, status, RetValue = -1;
 
     // perform partitioning according to the selected algorithm
     clk = clock();
diff --git a/src/aig/dar/darCore.c b/src/aig/dar/darCore.c
index ed461de5..3916a0b0 100644
--- a/src/aig/dar/darCore.c
+++ b/src/aig/dar/darCore.c
@@ -264,7 +264,7 @@ Aig_MmFixed_t * Dar_ManComputeCuts( Aig_Man_t * pAig, int nCutsMax, int fVerbose
         printf( "Nodes = %6d. Total cuts = %6d. 4-input cuts = %6d.\n",
             Aig_ManObjNum(pAig), nCuts, nCutsK );
         printf( "Cut size = %2d. Truth size = %2d. Total mem = %5.2f Mb  ",
-            sizeof(Dar_Cut_t), (int)4, 1.0*Aig_MmFixedReadMemUsage(p->pMemCuts)/(1<<20) );
+            (int)sizeof(Dar_Cut_t), (int)4, 1.0*Aig_MmFixedReadMemUsage(p->pMemCuts)/(1<<20) );
         PRT( "Runtime", clock() - clk );
 /*
         Aig_ManForEachNode( pAig, pObj, i )
diff --git a/src/aig/fra/fraClass.c b/src/aig/fra/fraClass.c
index 442cf80e..064d2b9c 100644
--- a/src/aig/fra/fraClass.c
+++ b/src/aig/fra/fraClass.c
@@ -378,6 +378,7 @@ void Fra_ClassesPrepare( Fra_Cla_t * p, int fLatchCorr, int nMaxLevs )
     free( ppNexts );
     // now it is time to refine the classes
     Fra_ClassesRefine( p );
+//    Fra_ClassesPrint( p, 0 );
 }
 
 /**Function*************************************************************
diff --git a/src/aig/fra/fraInd.c b/src/aig/fra/fraInd.c
index 76c7abad..ce9ec69b 100644
--- a/src/aig/fra/fraInd.c
+++ b/src/aig/fra/fraInd.c
@@ -568,7 +568,7 @@ p->timeTrav += clock() - clk2;
             Fra_OneHotAssume( p, p->vOneHots );
 //        if ( p->pManAig->vOnehots )
 //            Fra_OneHotAddKnownConstraint( p, p->pManAig->vOnehots );
-
+ 
         // report the intermediate results
         if ( pPars->fVerbose )
         {
@@ -580,7 +580,6 @@ p->timeTrav += clock() - clk2;
             if ( p->pPars->fUse1Hot )
                 printf( "1h = %6d. ", Fra_OneHotCount(p, p->vOneHots) );
             printf( "NR = %6d. ", Aig_ManNodeNum(p->pManFraig) );
-            PRT( "T", clock() - clk3 );
 //            printf( "\n" );
         } 
 
@@ -593,12 +592,13 @@ clk2 = clock();
         Fra_FraigSweep( p );
         if ( pPars->fVerbose )
         {
-//            PRT( "t", clock() - clk2 ); 
+            PRT( "T", clock() - clk3 );
         } 
 
 //        Sat_SolverPrintStats( stdout, p->pSat );
         // remove FRAIG and SAT solver
         Aig_ManStop( p->pManFraig );   p->pManFraig = NULL;
+//        printf( "Vars = %d. Clauses = %d. Learnts = %d.\n", p->pSat->size, p->pSat->clauses.size, p->pSat->learnts.size );
         sat_solver_delete( p->pSat );  p->pSat = NULL; 
         memset( p->pMemFraig, 0, sizeof(Aig_Obj_t *) * p->nSizeAlloc * p->nFramesAll );
 //        printf( "Recent SAT called = %d. Skipped = %d.\n", p->nSatCallsRecent, p->nSatCallsSkipped );
diff --git a/src/aig/fra/fraLcr.c b/src/aig/fra/fraLcr.c
index 92e0d94b..4b2383aa 100644
--- a/src/aig/fra/fraLcr.c
+++ b/src/aig/fra/fraLcr.c
@@ -629,6 +629,9 @@ clk2 = clock();
 p->timeFraig += clock() - clk2;
             Vec_PtrPush( p->vFraigs, pAigTemp );
             Aig_ManStop( pAigPart );
+
+//intf( "finished part %d (out of %d)\n", i, Vec_PtrSize(p->vParts) );
+
         }
         Fra_ClassNodesUnmark( p );
         // report the intermediate results
diff --git a/src/aig/saig/saigPhase.c b/src/aig/saig/saigPhase.c
index 323a230f..12d323e2 100644
--- a/src/aig/saig/saigPhase.c
+++ b/src/aig/saig/saigPhase.c
@@ -886,6 +886,11 @@ Aig_Man_t * Saig_ManPhaseAbstractAuto( Aig_Man_t * p, int fVerbose )
     Saig_TsiStop( pTsi );
     if ( pNew == NULL )
         pNew = Aig_ManDupSimple( p );
+    if ( Aig_ManPiNum(pNew) == Aig_ManRegNum(pNew) )
+    {
+        Aig_ManStop( pNew);
+        pNew = Aig_ManDupSimple( p );
+    }
     return pNew;
 }
 
diff --git a/src/aig/ssw/module.make b/src/aig/ssw/module.make
index dcbe0081..2619751e 100644
--- a/src/aig/ssw/module.make
+++ b/src/aig/ssw/module.make
@@ -4,5 +4,6 @@ SRC +=    src/aig/ssw/sswAig.c \
     src/aig/ssw/sswCore.c \
     src/aig/ssw/sswMan.c \
     src/aig/ssw/sswSat.c \
+    src/aig/ssw/sswSim.c \
     src/aig/ssw/sswSimSat.c \
     src/aig/ssw/sswSweep.c
diff --git a/src/aig/ssw/ssw.h b/src/aig/ssw/ssw.h
index 3bdc63f6..aaaa6407 100644
--- a/src/aig/ssw/ssw.h
+++ b/src/aig/ssw/ssw.h
@@ -54,6 +54,18 @@ struct Ssw_Pars_t_
     int              nIters;        // the number of iterations performed
 };
 
+// sequential counter-example
+typedef struct Ssw_Cex_t_   Ssw_Cex_t;
+struct Ssw_Cex_t_
+{
+    int              iPo;               // the zero-based number of PO, for which verification failed
+    int              iFrame;            // the zero-based number of the time-frame, for which verificaiton failed
+    int              nRegs;             // the number of registers in the miter 
+    int              nPis;              // the number of primary inputs in the miter
+    int              nBits;             // the number of words of bit data used
+    unsigned         pData[0];          // the cex bit data (the number of bits: nRegs + (iFrame+1) * nPis)
+};
+
 ////////////////////////////////////////////////////////////////////////
 ///                      MACRO DEFINITIONS                           ///
 ////////////////////////////////////////////////////////////////////////
diff --git a/src/aig/ssw/sswAig.c b/src/aig/ssw/sswAig.c
index 9304edc7..854a0e12 100644
--- a/src/aig/ssw/sswAig.c
+++ b/src/aig/ssw/sswAig.c
@@ -28,7 +28,6 @@
 ///                     FUNCTION DEFINITIONS                         ///
 ////////////////////////////////////////////////////////////////////////
 
-
 /**Function*************************************************************
 
   Synopsis    [Performs speculative reduction for one node.]
diff --git a/src/aig/ssw/sswClass.c b/src/aig/ssw/sswClass.c
index c84a5d3d..66b86009 100644
--- a/src/aig/ssw/sswClass.c
+++ b/src/aig/ssw/sswClass.c
@@ -335,7 +335,7 @@ void Ssw_ClassesPrint( Ssw_Cla_t * p, int fVeryVerbose )
     Aig_Obj_t * pObj;
     int i;
     printf( "Equivalence classes: Const1 = %5d. Class = %5d. Lit = %5d.\n", 
-        p->nCands1, p->nClasses, p->nLits );
+        p->nCands1, p->nClasses, p->nCands1+p->nLits );
     if ( !fVeryVerbose )
         return;
     printf( "Constants { " );
@@ -368,12 +368,13 @@ void Ssw_ClassesRemoveNode( Ssw_Cla_t * p, Aig_Obj_t * pObj )
     assert( p->pId2Class[pObj->Id] == NULL );
     pRepr = Aig_ObjRepr( p->pAig, pObj );
     assert( pRepr != NULL );
-    Aig_ObjSetRepr( p->pAig, pObj, NULL );
     if ( Ssw_ObjIsConst1Cand( p->pAig, pObj ) )
     {
+        Aig_ObjSetRepr( p->pAig, pObj, NULL );
         p->nCands1--;
         return;
     }
+    Aig_ObjSetRepr( p->pAig, pObj, NULL );
     assert( p->pId2Class[pRepr->Id][0] == pRepr );
     assert( p->pClassSizes[pRepr->Id] >= 2 );
     if ( p->pClassSizes[pRepr->Id] == 2 )
@@ -408,11 +409,26 @@ void Ssw_ClassesRemoveNode( Ssw_Cla_t * p, Aig_Obj_t * pObj )
   SeeAlso     []
 
 ***********************************************************************/
-void Ssw_ClassesPrepare( Ssw_Cla_t * p, int fLatchCorr, int nMaxLevs )
+Ssw_Cla_t * Ssw_ClassesPrepare( Aig_Man_t * pAig, int fLatchCorr, int nMaxLevs )
 {
+    Ssw_Cla_t * p;
+    Ssw_Sml_t * pSml;
     Aig_Obj_t ** ppTable, ** ppNexts, ** ppClassNew;
     Aig_Obj_t * pObj, * pTemp, * pRepr;
     int i, k, nTableSize, nNodes, iEntry, nEntries, nEntries2;
+    int clk;
+
+    // start the classes
+    p = Ssw_ClassesStart( pAig );
+
+    // perform sequential simulation
+clk = clock();
+    pSml = Ssw_SmlSimulateSeq( pAig, 0, 32, 4 );
+PRT( "Simulation of 32 frames with 4 words", clock() - clk );
+
+    // set comparison procedures
+clk = clock();
+    Ssw_ClassesSetData( p, pSml, Ssw_SmlNodeHash, Ssw_SmlNodeIsConst, Ssw_SmlNodesAreEqual );
 
     // allocate the hash table hashing simulation info into nodes
     nTableSize = Aig_PrimeCudd( Aig_ManObjNumMax(p->pAig)/4 );
@@ -430,7 +446,7 @@ void Ssw_ClassesPrepare( Ssw_Cla_t * p, int fLatchCorr, int nMaxLevs )
         }
         else
         {
-            if ( !Aig_ObjIsNode(pObj) && !Saig_ObjIsPi(p->pAig, pObj) )
+            if ( !Aig_ObjIsNode(pObj) && !Aig_ObjIsPi(pObj) )
                 continue;
             // skip the node with more that the given number of levels
             if ( nMaxLevs && (int)pObj->Level > nMaxLevs )
@@ -499,9 +515,14 @@ void Ssw_ClassesPrepare( Ssw_Cla_t * p, int fLatchCorr, int nMaxLevs )
     assert( nEntries == nEntries2 );
     free( ppTable );
     free( ppNexts );
+
     // now it is time to refine the classes
-    Ssw_ClassesRefine( p );
+    Ssw_ClassesRefine( p, 1 );
     Ssw_ClassesCheck( p );
+    Ssw_SmlStop( pSml );
+//    Ssw_ClassesPrint( p, 0 );
+PRT( "Collecting candidate equival classes", clock() - clk );
+    return p;
 }
 
 /**Function*************************************************************
@@ -654,12 +675,12 @@ int Ssw_ClassesRefineOneClass( Ssw_Cla_t * p, Aig_Obj_t * pReprOld, int fRecursi
   SeeAlso     []
 
 ***********************************************************************/
-int Ssw_ClassesRefine( Ssw_Cla_t * p )
+int Ssw_ClassesRefine( Ssw_Cla_t * p, int fRecursive )
 {
     Aig_Obj_t ** ppClass;
     int i, nRefis = 0;
     Ssw_ManForEachClass( p, ppClass, i )
-        nRefis += Ssw_ClassesRefineOneClass( p, ppClass[0], 0 );
+        nRefis += Ssw_ClassesRefineOneClass( p, ppClass[0], fRecursive );
     return nRefis;
 }
 
diff --git a/src/aig/ssw/sswCnf.c b/src/aig/ssw/sswCnf.c
index f5047400..b047a312 100644
--- a/src/aig/ssw/sswCnf.c
+++ b/src/aig/ssw/sswCnf.c
@@ -264,8 +264,8 @@ void Ssw_ObjAddToFrontier( Ssw_Man_t * p, Aig_Obj_t * pObj, Vec_Ptr_t * vFrontie
     assert( Ssw_ObjSatNum(p,pObj) == 0 );
     if ( Aig_ObjIsConst1(pObj) )
         return;
-//    Vec_PtrPush( p->vUsedNodes, pObj );
     Ssw_ObjSetSatNum( p, pObj, p->nSatVars++ );
+    sat_solver_setnvars( p->pSat, 100 * (1 + p->nSatVars / 100) );
     if ( Aig_ObjIsNode(pObj) )
         Vec_PtrPush( vFrontier, pObj );
 }
diff --git a/src/aig/ssw/sswCore.c b/src/aig/ssw/sswCore.c
index 6c19ab70..409a1ebe 100644
--- a/src/aig/ssw/sswCore.c
+++ b/src/aig/ssw/sswCore.c
@@ -48,8 +48,8 @@ void Ssw_ManSetDefaultParams( Ssw_Pars_t * p )
     p->nConstrs       =     0;  // treat the last nConstrs POs as seq constraints
     p->nBTLimit       =  1000;  // conflict limit at a node
     p->fPolarFlip     =     0;  // uses polarity adjustment
-    p->fLatchCorr     =     1;  // performs register correspondence
-    p->fVerbose       =     1;  // verbose stats
+    p->fLatchCorr     =     0;  // performs register correspondence
+    p->fVerbose       =     0;  // verbose stats
     p->nIters         =     0;  // the number of iterations performed
 }
 
@@ -70,18 +70,40 @@ Aig_Man_t * Ssw_SignalCorrespondence( Aig_Man_t * pAig, Ssw_Pars_t * pPars )
     Ssw_Man_t * p;
     int RetValue, nIter, clk, clkTotal = clock();
     // reset random numbers
-    Aig_ManRandom(1);
+    Aig_ManRandom( 1 );
     // start the choicing manager
     p = Ssw_ManCreate( pAig, pPars );
     // compute candidate equivalence classes
-    p->ppClasses = Ssw_ClassesPrepareSimple( pAig, pPars->fLatchCorr, pPars->nMaxLevs );
+    if ( p->pPars->nConstrs == 0 )
+    {
+        p->ppClasses = Ssw_ClassesPrepare( pAig, pPars->fLatchCorr, pPars->nMaxLevs );
+        p->pSml = Ssw_SmlStart( pAig, 0, p->nFrames + 2, 2 );
+        Ssw_ClassesSetData( p->ppClasses, p->pSml, Ssw_SmlNodeHash, Ssw_SmlNodeIsConst, Ssw_SmlNodesAreEqual );
+    }
+    else
+    {
+        assert( 0 );
+        p->ppClasses = Ssw_ClassesPrepareSimple( pAig, pPars->fLatchCorr, pPars->nMaxLevs );
+    }
+//    Ssw_ClassesSetData( p->ppClasses, NULL, NULL, Ssw_NodeIsConstCex, Ssw_NodesAreEqualCex );
+
+    // get the starting stats
+    p->nLitsBeg  = Ssw_ClassesLitNum( p->ppClasses );
+    p->nNodesBeg = Aig_ManNodeNum(pAig);
+    p->nRegsBeg  = Aig_ManRegNum(pAig);
     // refine classes using BMC
     if ( pPars->fVerbose )
+    {
+        printf( "Before BMC: " );
         Ssw_ClassesPrint( p->ppClasses, 0 );
+    }
     Ssw_ManSweepBmc( p );
     Ssw_ManCleanup( p );
     if ( pPars->fVerbose )
+    {
+        printf( "After  BMC: " );
         Ssw_ClassesPrint( p->ppClasses, 0 );
+    }
     // refine classes using induction
     for ( nIter = 0; ; nIter++ )
     {
@@ -98,10 +120,16 @@ clk = clock();
         if ( !RetValue )
             break;
     } 
+    p->pPars->nIters = nIter + 1;
 p->timeTotal = clock() - clkTotal;
-    Ssw_ManStop( p );
     pAigNew = Aig_ManDupRepr( pAig, 0 );
     Aig_ManSeqCleanup( pAigNew );
+    // get the final stats
+    p->nLitsEnd  = Ssw_ClassesLitNum( p->ppClasses );
+    p->nNodesEnd = Aig_ManNodeNum(pAigNew);
+    p->nRegsEnd  = Aig_ManRegNum(pAigNew);
+    // cleanup
+    Ssw_ManStop( p );
     return pAigNew;
 }
 
diff --git a/src/aig/ssw/sswInt.h b/src/aig/ssw/sswInt.h
index 21621c0d..009c09c4 100644
--- a/src/aig/ssw/sswInt.h
+++ b/src/aig/ssw/sswInt.h
@@ -41,11 +41,10 @@ extern "C" {
 ///                         BASIC TYPES                              ///
 ////////////////////////////////////////////////////////////////////////
 
-// equivalence classes
-typedef struct Ssw_Cla_t_ Ssw_Cla_t;
+typedef struct Ssw_Man_t_ Ssw_Man_t; // signal correspondence manager
+typedef struct Ssw_Cla_t_ Ssw_Cla_t; // equivalence classe manager
+typedef struct Ssw_Sml_t_ Ssw_Sml_t; // sequential simulation manager
 
-// manager
-typedef struct Ssw_Man_t_ Ssw_Man_t;
 struct Ssw_Man_t_
 {
     // parameters
@@ -57,25 +56,38 @@ struct Ssw_Man_t_
     Aig_Obj_t **     pNodeToFraig;   // mapping of AIG nodes into FRAIG nodes
     // equivalence classes
     Ssw_Cla_t *      ppClasses;      // equivalence classes of nodes
-//    Aig_Obj_t **     pReprsProved;   // equivalences proved
     int              fRefined;       // is set to 1 when refinement happens
     // SAT solving
     sat_solver *     pSat;           // recyclable SAT solver
     int              nSatVars;       // the counter of SAT variables
     int *            pSatVars;       // mapping of each node into its SAT var
+    int              nSatVarsTotal;  // the total number of SAT vars created
     Vec_Ptr_t *      vFanins;        // fanins of the CNF node
     Vec_Ptr_t *      vSimRoots;      // the roots of cand const 1 nodes to simulate
     Vec_Ptr_t *      vSimClasses;    // the roots of cand equiv classes to simulate
+    // sequential simulator
+    Ssw_Sml_t *      pSml;
+    // counter example storage
+    int              nPatWords;      // the number of words in the counter example
+    unsigned *       pPatWords;      // the counter example
     // constraints
     int              nConstrTotal;   // the number of total constraints
     int              nConstrReduced; // the number of reduced constraints
-    int              nStragers;
+    int              nStrangers;     // the number of strange situations
     // SAT calls statistics
     int              nSatCalls;      // the number of SAT calls
     int              nSatProof;      // the number of proofs
+    int              nSatFails;      // the number of timeouts
     int              nSatFailsReal;  // the number of timeouts
     int              nSatCallsUnsat; // the number of unsat SAT calls
     int              nSatCallsSat;   // the number of sat SAT calls
+    // node/register/lit statistics
+    int              nLitsBeg;
+    int              nLitsEnd;
+    int              nNodesBeg;
+    int              nNodesEnd;
+    int              nRegsBeg;
+    int              nRegsEnd;
     // runtime stats
     int              timeBmc;        // bounded model checking
     int              timeReduce;     // speculative reduction
@@ -131,12 +143,14 @@ extern Aig_Obj_t **  Ssw_ClassesReadClass( Ssw_Cla_t * p, Aig_Obj_t * pRepr, int
 extern void          Ssw_ClassesCheck( Ssw_Cla_t * p );
 extern void          Ssw_ClassesPrint( Ssw_Cla_t * p, int fVeryVerbose );
 extern void          Ssw_ClassesRemoveNode( Ssw_Cla_t * p, Aig_Obj_t * pObj );
-extern void          Ssw_ClassesPrepare( Ssw_Cla_t * p, int fLatchCorr, int nMaxLevs );
+extern Ssw_Cla_t * Ssw_ClassesPrepare( Aig_Man_t * pAig, int fLatchCorr, int nMaxLevs );
 extern Ssw_Cla_t *   Ssw_ClassesPrepareSimple( Aig_Man_t * pAig, int fLatchCorr, int nMaxLevs );
-extern int           Ssw_ClassesRefine( Ssw_Cla_t * p );
+extern int           Ssw_ClassesRefine( Ssw_Cla_t * p, int fRecursive );
 extern int           Ssw_ClassesRefineOneClass( Ssw_Cla_t * p, Aig_Obj_t * pRepr, int fRecursive );
 extern int           Ssw_ClassesRefineConst1Group( Ssw_Cla_t * p, Vec_Ptr_t * vRoots, int fRecursive );
 extern int           Ssw_ClassesRefineConst1( Ssw_Cla_t * p, int fRecursive );
+extern int           Ssw_NodeIsConstCex( void * p, Aig_Obj_t * pObj );
+extern int           Ssw_NodesAreEqualCex( void * p, Aig_Obj_t * pObj0, Aig_Obj_t * pObj1 );
 /*=== sswCnf.c ===================================================*/
 extern void          Ssw_CnfNodeAddToSolver( Ssw_Man_t * p, Aig_Obj_t * pObj );
 /*=== sswMan.c ===================================================*/
@@ -147,9 +161,19 @@ extern void          Ssw_ManStartSolver( Ssw_Man_t * p );
 /*=== sswSat.c ===================================================*/
 extern int           Ssw_NodesAreEquiv( Ssw_Man_t * p, Aig_Obj_t * pOld, Aig_Obj_t * pNew );
 extern int           Ssw_NodesAreConstrained( Ssw_Man_t * p, Aig_Obj_t * pOld, Aig_Obj_t * pNew );
+/*=== sswSim.c ===================================================*/
+extern Ssw_Sml_t *   Ssw_SmlStart( Aig_Man_t * pAig, int nPref, int nFrames, int nWordsFrame );
+extern void          Ssw_SmlStop( Ssw_Sml_t * p );
+extern Ssw_Sml_t *   Ssw_SmlSimulateSeq( Aig_Man_t * pAig, int nPref, int nFrames, int nWords );
+extern unsigned      Ssw_SmlNodeHash( Ssw_Sml_t * p, Aig_Obj_t * pObj );
+extern int           Ssw_SmlNodeIsConst( Ssw_Sml_t * p, Aig_Obj_t * pObj );
+extern int           Ssw_SmlNodesAreEqual( Ssw_Sml_t * p, Aig_Obj_t * pObj0, Aig_Obj_t * pObj1 );
+extern void          Ssw_SmlAssignDist1Plus( Ssw_Sml_t * p, unsigned * pPat );
+extern void          Ssw_SmlSimulateOne( Ssw_Sml_t * p );
 /*=== sswSimSat.c ===================================================*/
 extern void          Ssw_ManResimulateCex( Ssw_Man_t * p, Aig_Obj_t * pObj, Aig_Obj_t * pRepr, int f );
 extern void          Ssw_ManResimulateCexTotal( Ssw_Man_t * p, Aig_Obj_t * pObj, Aig_Obj_t * pRepr, int f );
+extern void          Ssw_ManResimulateCexTotalSim( Ssw_Man_t * p, Aig_Obj_t * pCand, Aig_Obj_t * pRepr, int f );
 /*=== sswSweep.c ===================================================*/
 extern int           Ssw_ManSweepBmc( Ssw_Man_t * p );
 extern int           Ssw_ManSweep( Ssw_Man_t * p );
diff --git a/src/aig/ssw/sswMan.c b/src/aig/ssw/sswMan.c
index 0b935daa..a6e02125 100644
--- a/src/aig/ssw/sswMan.c
+++ b/src/aig/ssw/sswMan.c
@@ -49,18 +49,18 @@ Ssw_Man_t * Ssw_ManCreate( Aig_Man_t * pAig, Ssw_Pars_t * pPars )
     // create interpolation manager
     p = ALLOC( Ssw_Man_t, 1 );
     memset( p, 0, sizeof(Ssw_Man_t) );
-    p->pPars        = pPars;
-    p->pAig         = pAig;
-    p->nFrames      = pPars->nFramesK + 1;
-    p->pNodeToFraig = CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(p->pAig) * p->nFrames );
+    p->pPars         = pPars;
+    p->pAig          = pAig;
+    p->nFrames       = pPars->nFramesK + 1;
+    p->pNodeToFraig  = CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(p->pAig) * p->nFrames );
     // SAT solving
-    p->nSatVars     = 1;
-    p->pSatVars     = CALLOC( int, Aig_ManObjNumMax(p->pAig) * p->nFrames );
-    p->vFanins      = Vec_PtrAlloc( 100 );
-    p->vSimRoots    = Vec_PtrAlloc( 1000 );
-    p->vSimClasses  = Vec_PtrAlloc( 1000 );
-    // equivalences proved
-//    p->pReprsProved = CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(p->pAig) );
+    p->pSatVars      = CALLOC( int, Aig_ManObjNumMax(p->pAig) * p->nFrames );
+    p->vFanins       = Vec_PtrAlloc( 100 );
+    p->vSimRoots     = Vec_PtrAlloc( 1000 );
+    p->vSimClasses   = Vec_PtrAlloc( 1000 );
+    // allocate storage for sim pattern
+    p->nPatWords     = Aig_BitWordNum( Saig_ManPiNum(pAig) * p->nFrames + Saig_ManRegNum(pAig) );
+    p->pPatWords     = ALLOC( unsigned, p->nPatWords ); 
     return p;
 }
 
@@ -80,7 +80,6 @@ int Ssw_ManCountEquivs( Ssw_Man_t * p )
     Aig_Obj_t * pObj;
     int i, nEquivs = 0;
     Aig_ManForEachObj( p->pAig, pObj, i )
-//        nEquivs += ( p->pReprsProved[i] != NULL );
         nEquivs += ( Aig_ObjRepr(p->pAig, pObj) != NULL );
     return nEquivs;
 }
@@ -98,14 +97,19 @@ int Ssw_ManCountEquivs( Ssw_Man_t * p )
 ***********************************************************************/
 void Ssw_ManPrintStats( Ssw_Man_t * p )
 {
-    printf( "Parameters: Frames = %d. Conf limit = %d. Constrs = %d.\n", 
-        p->pPars->nFramesK, p->pPars->nBTLimit, p->pPars->nConstrs );
-    printf( "AIG       : PI = %d. PO = %d. Latch = %d. Node = %d.  SAT vars = %d.\n", 
-        Saig_ManPiNum(p->pAig), Saig_ManPoNum(p->pAig), Saig_ManRegNum(p->pAig), Aig_ManNodeNum(p->pAig), p->nSatVars );
-    printf( "SAT calls : All = %6d. Unsat = %6d. Sat = %6d. Fail = %6d.  Equivs = %d. Str = %d.\n", 
-        p->nSatCalls, p->nSatCalls-p->nSatCallsSat-p->nSatFailsReal, 
-        p->nSatCallsSat, p->nSatFailsReal, Ssw_ManCountEquivs(p), p->nStragers );
-    printf( "Runtime statistics:\n" );
+    double nMemory = 1.0*Aig_ManObjNumMax(p->pAig)*p->nFrames*(2*sizeof(int)+2*sizeof(void*))/(1<<20);
+
+    printf( "Parameters: Frames = %d. Conf limit = %d. Constrs = %d. Max lev = %d. Mem = %0.2f Mb.\n", 
+        p->pPars->nFramesK, p->pPars->nBTLimit, p->pPars->nConstrs, p->pPars->nMaxLevs, nMemory );
+    printf( "AIG       : PI = %d. PO = %d. Latch = %d. Node = %d.  Ave SAT vars = %d.\n", 
+        Saig_ManPiNum(p->pAig), Saig_ManPoNum(p->pAig), Saig_ManRegNum(p->pAig), Aig_ManNodeNum(p->pAig), 
+        p->nSatVarsTotal/p->pPars->nIters );
+    printf( "SAT calls : Proof = %d. Cex = %d. Fail = %d. FailReal = %d.  Equivs = %d. Str = %d.\n", 
+        p->nSatProof, p->nSatCallsSat, p->nSatFails, p->nSatFailsReal, Ssw_ManCountEquivs(p), p->nStrangers );
+    printf( "NBeg = %d. NEnd = %d. (Gain = %6.2f %%).  RBeg = %d. REnd = %d. (Gain = %6.2f %%).\n", 
+        p->nNodesBeg, p->nNodesEnd, 100.0*(p->nNodesBeg-p->nNodesEnd)/(p->nNodesBeg?p->nNodesBeg:1), 
+        p->nRegsBeg, p->nRegsEnd, 100.0*(p->nRegsBeg-p->nRegsEnd)/(p->nRegsBeg?p->nRegsBeg:1) );
+
     p->timeOther = p->timeTotal-p->timeBmc-p->timeReduce-p->timeSimSat-p->timeSat;
     PRTP( "BMC        ", p->timeBmc,      p->timeTotal );
     PRTP( "Spec reduce", p->timeReduce,   p->timeTotal );
@@ -140,9 +144,10 @@ void Ssw_ManCleanup( Ssw_Man_t * p )
     }
     if ( p->pSat )
     {
+//        printf( "Vars = %d. Clauses = %d. Learnts = %d.\n", p->pSat->size, p->pSat->clauses.size, p->pSat->learnts.size );
+        p->nSatVarsTotal += p->pSat->size;
         sat_solver_delete( p->pSat );
         p->pSat = NULL;
-//        p->nSatVars = 0;
         memset( p->pSatVars, 0, sizeof(int) * Aig_ManObjNumMax(p->pAig) * p->nFrames );
     }
     p->nConstrTotal = 0;
@@ -166,12 +171,14 @@ void Ssw_ManStop( Ssw_Man_t * p )
         Ssw_ManPrintStats( p );
     if ( p->ppClasses )
         Ssw_ClassesStop( p->ppClasses );
+    if ( p->pSml )      
+        Ssw_SmlStop( p->pSml );
     Vec_PtrFree( p->vFanins );
     Vec_PtrFree( p->vSimRoots );
     Vec_PtrFree( p->vSimClasses );
     FREE( p->pNodeToFraig );
-//    FREE( p->pReprsProved );
     FREE( p->pSatVars );
+    FREE( p->pPatWords );
     free( p );
 }
 
@@ -191,7 +198,7 @@ void Ssw_ManStartSolver( Ssw_Man_t * p )
     int Lit;
     assert( p->pSat == NULL );
     p->pSat = sat_solver_new();
-    sat_solver_setnvars( p->pSat, 10000 );
+    sat_solver_setnvars( p->pSat, 1000 );
     // var 0 is not used
     // var 1 is reserved for const1 node - add the clause
     p->nSatVars = 1;
diff --git a/src/aig/ssw/sswSat.c b/src/aig/ssw/sswSat.c
index 90752baa..264b39d1 100644
--- a/src/aig/ssw/sswSat.c
+++ b/src/aig/ssw/sswSat.c
@@ -68,8 +68,11 @@ int Ssw_NodesAreEquiv( Ssw_Man_t * p, Aig_Obj_t * pOld, Aig_Obj_t * pNew )
     }
 //Sat_SolverWriteDimacs( p->pSat, "temp.cnf", pLits, pLits + 2, 1 );
 
-    RetValue = sat_solver_simplify(p->pSat);
-    assert( RetValue != 0 );
+    if ( p->pSat->qtail != p->pSat->qhead )
+    {
+        RetValue = sat_solver_simplify(p->pSat);
+        assert( RetValue != 0 );
+    }
 
 clk = clock();
     RetValue1 = sat_solver_solve( p->pSat, pLits, pLits + 2, 
@@ -114,8 +117,11 @@ p->timeSatUndec += clock() - clk;
         if ( pNew->fPhase )  pLits[1] = lit_neg( pLits[1] );
     }
 
-    RetValue = sat_solver_simplify(p->pSat);
-    assert( RetValue != 0 );
+    if ( p->pSat->qtail != p->pSat->qhead )
+    {
+        RetValue = sat_solver_simplify(p->pSat);
+        assert( RetValue != 0 );
+    }
 
 clk = clock();
     RetValue1 = sat_solver_solve( p->pSat, pLits, pLits + 2, 
diff --git a/src/aig/ssw/sswSim.c b/src/aig/ssw/sswSim.c
new file mode 100644
index 00000000..64175b40
--- /dev/null
+++ b/src/aig/ssw/sswSim.c
@@ -0,0 +1,1263 @@
+/**CFile****************************************************************
+
+  FileName    [sswSim.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [Inductive prover with constraints.]
+
+  Synopsis    [Sequential simulator used by the inductive prover.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - September 1, 2008.]
+
+  Revision    [$Id: sswSim.c,v 1.00 2008/09/01 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "sswInt.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+// simulation manager
+struct Ssw_Sml_t_
+{
+    Aig_Man_t *      pAig;              // the original AIG manager
+    int              nPref;             // the number of timeframes in the prefix
+    int              nFrames;           // the number of timeframes 
+    int              nWordsFrame;       // the number of words in each timeframe
+    int              nWordsTotal;       // the total number of words at a node
+    int              nWordsPref;        // the number of word in the prefix
+    int              fNonConstOut;      // have seen a non-const-0 output during simulation
+    int              nSimRounds;        // statistics
+    int              timeSim;           // statistics
+    unsigned         pData[0];          // simulation data for the nodes
+};
+
+static inline unsigned * Ssw_ObjSim( Ssw_Sml_t * p, int Id )  { return p->pData + p->nWordsTotal * Id; }
+static inline unsigned   Ssw_ObjRandomSim()                   { return Aig_ManRandom(0);               }
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Computes hash value of the node using its simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+unsigned Ssw_SmlNodeHash( Ssw_Sml_t * p, Aig_Obj_t * pObj )
+{
+    static int s_SPrimes[128] = { 
+        1009, 1049, 1093, 1151, 1201, 1249, 1297, 1361, 1427, 1459, 
+        1499, 1559, 1607, 1657, 1709, 1759, 1823, 1877, 1933, 1997, 
+        2039, 2089, 2141, 2213, 2269, 2311, 2371, 2411, 2467, 2543, 
+        2609, 2663, 2699, 2741, 2797, 2851, 2909, 2969, 3037, 3089, 
+        3169, 3221, 3299, 3331, 3389, 3461, 3517, 3557, 3613, 3671, 
+        3719, 3779, 3847, 3907, 3943, 4013, 4073, 4129, 4201, 4243, 
+        4289, 4363, 4441, 4493, 4549, 4621, 4663, 4729, 4793, 4871, 
+        4933, 4973, 5021, 5087, 5153, 5227, 5281, 5351, 5417, 5471, 
+        5519, 5573, 5651, 5693, 5749, 5821, 5861, 5923, 6011, 6073, 
+        6131, 6199, 6257, 6301, 6353, 6397, 6481, 6563, 6619, 6689, 
+        6737, 6803, 6863, 6917, 6977, 7027, 7109, 7187, 7237, 7309, 
+        7393, 7477, 7523, 7561, 7607, 7681, 7727, 7817, 7877, 7933, 
+        8011, 8039, 8059, 8081, 8093, 8111, 8123, 8147
+    };
+    unsigned * pSims;
+    unsigned uHash;
+    int i;
+    assert( p->nWordsTotal <= 128 );
+    uHash = 0;
+    pSims = Ssw_ObjSim(p, pObj->Id);
+    for ( i = p->nWordsPref; i < p->nWordsTotal; i++ )
+        uHash ^= pSims[i] * s_SPrimes[i & 0x7F];
+    return uHash;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if simulation info is composed of all zeros.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlNodeIsConst( Ssw_Sml_t * p, Aig_Obj_t * pObj )
+{
+    unsigned * pSims;
+    int i;
+    pSims = Ssw_ObjSim(p, pObj->Id);
+    for ( i = p->nWordsPref; i < p->nWordsTotal; i++ )
+        if ( pSims[i] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if simulation infos are equal.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlNodesAreEqual( Ssw_Sml_t * p, Aig_Obj_t * pObj0, Aig_Obj_t * pObj1 )
+{
+    unsigned * pSims0, * pSims1;
+    int i;
+    pSims0 = Ssw_ObjSim(p, pObj0->Id);
+    pSims1 = Ssw_ObjSim(p, pObj1->Id);
+    for ( i = p->nWordsPref; i < p->nWordsTotal; i++ )
+        if ( pSims0[i] != pSims1[i] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of 1s in the XOR of simulation data.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlNodeNotEquWeight( Ssw_Sml_t * p, int Left, int Right )
+{
+    unsigned * pSimL, * pSimR;
+    int k, Counter = 0;
+    pSimL = Ssw_ObjSim( p, Left );
+    pSimR = Ssw_ObjSim( p, Right );
+    for ( k = p->nWordsPref; k < p->nWordsTotal; k++ )
+        Counter += Aig_WordCountOnes( pSimL[k] ^ pSimR[k] );
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if simulation info is composed of all zeros.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlNodeIsZero( Ssw_Sml_t * p, Aig_Obj_t * pObj )
+{
+    unsigned * pSims;
+    int i;
+    pSims = Ssw_ObjSim(p, pObj->Id);
+    for ( i = p->nWordsPref; i < p->nWordsTotal; i++ )
+        if ( pSims[i] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Counts the number of one's in the patten of the output.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlNodeCountOnes( Ssw_Sml_t * p, Aig_Obj_t * pObj )
+{
+    unsigned * pSims;
+    int i, Counter = 0;
+    pSims = Ssw_ObjSim(p, pObj->Id);
+    for ( i = 0; i < p->nWordsTotal; i++ )
+        Counter += Aig_WordCountOnes( pSims[i] );
+    return Counter;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Generated const 0 pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlSavePattern0( Ssw_Man_t * p, int fInit )
+{
+    memset( p->pPatWords, 0, sizeof(unsigned) * p->nPatWords );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [[Generated const 1 pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlSavePattern1( Ssw_Man_t * p, int fInit )
+{
+    Aig_Obj_t * pObj;
+    int i, k, nTruePis;
+    memset( p->pPatWords, 0xff, sizeof(unsigned) * p->nPatWords );
+    if ( !fInit )
+        return;
+    // clear the state bits to correspond to all-0 initial state
+    nTruePis = Saig_ManPiNum(p->pAig);
+    k = 0;
+    Saig_ManForEachLo( p->pAig, pObj, i )
+        Aig_InfoXorBit( p->pPatWords, nTruePis * p->nFrames + k++ );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Copy pattern from the solver into the internal storage.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlSavePattern( Ssw_Man_t * p )
+{
+    Aig_Obj_t * pObj;
+    int i;
+    memset( p->pPatWords, 0, sizeof(unsigned) * p->nPatWords );
+    Aig_ManForEachPi( p->pFrames, pObj, i )
+        if ( p->pSat->model.ptr[Ssw_ObjSatNum(p, pObj)] == l_True )
+            Aig_InfoSetBit( p->pPatWords, i );
+/*
+    if ( p->vCex )
+    {
+        Vec_IntClear( p->vCex );
+        for ( i = 0; i < Saig_ManPiNum(p->pAig); i++ )
+            Vec_IntPush( p->vCex, Aig_InfoHasBit( p->pPatWords, i ) );
+        for ( i = Saig_ManPiNum(p->pFrames); i < Aig_ManPiNum(p->pFrames); i++ )
+            Vec_IntPush( p->vCex, Aig_InfoHasBit( p->pPatWords, i ) );
+    }
+*/
+
+/*
+    printf( "Pattern: " );
+    Aig_ManForEachPi( p->pFrames, pObj, i )
+        printf( "%d", Aig_InfoHasBit( p->pPatWords, i ) );
+    printf( "\n" );
+*/
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Creates the counter-example from the successful pattern.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int * Ssw_SmlCheckOutputSavePattern( Ssw_Sml_t * p, Aig_Obj_t * pObjPo )
+{ 
+    Aig_Obj_t * pFanin, * pObjPi;
+    unsigned * pSims;
+    int i, k, BestPat, * pModel;
+    // find the word of the pattern
+    pFanin = Aig_ObjFanin0(pObjPo);
+    pSims = Ssw_ObjSim(p, pFanin->Id);
+    for ( i = 0; i < p->nWordsTotal; i++ )
+        if ( pSims[i] )
+            break;
+    assert( i < p->nWordsTotal );
+    // find the bit of the pattern
+    for ( k = 0; k < 32; k++ )
+        if ( pSims[i] & (1 << k) )
+            break;
+    assert( k < 32 );
+    // determine the best pattern
+    BestPat = i * 32 + k;
+    // fill in the counter-example data
+    pModel = ALLOC( int, Aig_ManPiNum(p->pAig)+1 );
+    Aig_ManForEachPi( p->pAig, pObjPi, i )
+    {
+        pModel[i] = Aig_InfoHasBit(Ssw_ObjSim(p, pObjPi->Id), BestPat);
+//        printf( "%d", pModel[i] );
+    }
+    pModel[Aig_ManPiNum(p->pAig)] = pObjPo->Id;
+//    printf( "\n" );
+    return pModel;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 1 if the one of the output is already non-constant 0.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int * Ssw_SmlCheckOutput( Ssw_Sml_t * p )
+{
+    Aig_Obj_t * pObj;
+    int i;
+    // make sure the reference simulation pattern does not detect the bug
+    pObj = Aig_ManPo( p->pAig, 0 );
+    assert( Aig_ObjFanin0(pObj)->fPhase == (unsigned)Aig_ObjFaninC0(pObj) ); 
+    Aig_ManForEachPo( p->pAig, pObj, i )
+    {
+        if ( !Ssw_SmlNodeIsConst( p, Aig_ObjFanin0(pObj) ) )
+        {
+            // create the counter-example from this pattern
+            return Ssw_SmlCheckOutputSavePattern( p, pObj );
+        }
+    }
+    return NULL;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns random patterns to the PI node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlAssignRandom( Ssw_Sml_t * p, Aig_Obj_t * pObj )
+{
+    unsigned * pSims;
+    int i;
+    assert( Aig_ObjIsPi(pObj) );
+    pSims = Ssw_ObjSim( p, pObj->Id );
+    for ( i = 0; i < p->nWordsTotal; i++ )
+        pSims[i] = Ssw_ObjRandomSim();
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns random patterns to the PI node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlAssignRandomFrame( Ssw_Sml_t * p, Aig_Obj_t * pObj, int iFrame )
+{
+    unsigned * pSims;
+    int i;
+    assert( Aig_ObjIsPi(pObj) );
+    pSims = Ssw_ObjSim( p, pObj->Id ) + p->nWordsFrame * iFrame;
+    for ( i = 0; i < p->nWordsFrame; i++ )
+        pSims[i] = Ssw_ObjRandomSim();
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assigns constant patterns to the PI node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlAssignConst( Ssw_Sml_t * p, Aig_Obj_t * pObj, int fConst1, int iFrame )
+{
+    unsigned * pSims;
+    int i;
+    assert( Aig_ObjIsPi(pObj) );
+    pSims = Ssw_ObjSim( p, pObj->Id ) + p->nWordsFrame * iFrame;
+    for ( i = 0; i < p->nWordsFrame; i++ )
+        pSims[i] = fConst1? ~(unsigned)0 : 0;
+} 
+
+/**Function*************************************************************
+
+  Synopsis    [Assings random simulation info for the PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlInitialize( Ssw_Sml_t * p, int fInit )
+{
+    Aig_Obj_t * pObj;
+    int i;
+    if ( fInit )
+    {
+        assert( Aig_ManRegNum(p->pAig) > 0 );
+        assert( Aig_ManRegNum(p->pAig) < Aig_ManPiNum(p->pAig) );
+        // assign random info for primary inputs
+        Saig_ManForEachPi( p->pAig, pObj, i )
+            Ssw_SmlAssignRandom( p, pObj );
+        // assign the initial state for the latches
+        Saig_ManForEachLo( p->pAig, pObj, i )
+            Ssw_SmlAssignConst( p, pObj, 0, 0 );
+    }
+    else
+    {
+        Aig_ManForEachPi( p->pAig, pObj, i )
+            Ssw_SmlAssignRandom( p, pObj );
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assings distance-1 simulation info for the PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlAssignDist1( Ssw_Sml_t * p, unsigned * pPat )
+{
+    Aig_Obj_t * pObj;
+    int f, i, k, Limit, nTruePis;
+    assert( p->nFrames > 0 );
+    if ( p->nFrames == 1 )
+    {
+        // copy the PI info 
+        Aig_ManForEachPi( p->pAig, pObj, i )
+            Ssw_SmlAssignConst( p, pObj, Aig_InfoHasBit(pPat, i), 0 );
+        // flip one bit
+        Limit = AIG_MIN( Aig_ManPiNum(p->pAig), p->nWordsTotal * 32 - 1 );
+        for ( i = 0; i < Limit; i++ )
+            Aig_InfoXorBit( Ssw_ObjSim( p, Aig_ManPi(p->pAig,i)->Id ), i+1 );
+    }
+    else
+    {
+        int fUseDist1 = 0;
+
+        // copy the PI info for each frame
+        nTruePis = Aig_ManPiNum(p->pAig) - Aig_ManRegNum(p->pAig);
+        for ( f = 0; f < p->nFrames; f++ )
+            Saig_ManForEachPi( p->pAig, pObj, i )
+                Ssw_SmlAssignConst( p, pObj, Aig_InfoHasBit(pPat, nTruePis * f + i), f );
+        // copy the latch info 
+        k = 0;
+        Saig_ManForEachLo( p->pAig, pObj, i )
+            Ssw_SmlAssignConst( p, pObj, Aig_InfoHasBit(pPat, nTruePis * p->nFrames + k++), 0 );
+//        assert( p->pFrames == NULL || nTruePis * p->nFrames + k == Aig_ManPiNum(p->pFrames) );
+
+        // flip one bit of the last frame
+        if ( fUseDist1 ) //&& p->nFrames == 2 )
+        {
+            Limit = AIG_MIN( nTruePis, p->nWordsFrame * 32 - 1 );
+            for ( i = 0; i < Limit; i++ )
+                Aig_InfoXorBit( Ssw_ObjSim( p, Aig_ManPi(p->pAig, i)->Id ) + p->nWordsFrame*(p->nFrames-1), i+1 );
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Assings distance-1 simulation info for the PIs.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlAssignDist1Plus( Ssw_Sml_t * p, unsigned * pPat )
+{
+    Aig_Obj_t * pObj;
+    int f, i, Limit;
+    assert( p->nFrames > 0 );
+
+    // copy the pattern into the primary inputs
+    Aig_ManForEachPi( p->pAig, pObj, i )
+        Ssw_SmlAssignConst( p, pObj, Aig_InfoHasBit(pPat, i), 0 );
+
+    // set distance one PIs for the first frame
+    Limit = AIG_MIN( Saig_ManPiNum(p->pAig), p->nWordsFrame * 32 - 1 );
+    for ( i = 0; i < Limit; i++ )
+        Aig_InfoXorBit( Ssw_ObjSim( p, Aig_ManPi(p->pAig, i)->Id ), i+1 );
+
+    // create random info for the remaining timeframes
+    for ( f = 1; f < p->nFrames; f++ )
+        Saig_ManForEachPi( p->pAig, pObj, i )
+            Ssw_SmlAssignRandomFrame( p, pObj, f );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlNodeSimulate( Ssw_Sml_t * p, Aig_Obj_t * pObj, int iFrame )
+{
+    unsigned * pSims, * pSims0, * pSims1;
+    int fCompl, fCompl0, fCompl1, i;
+    assert( !Aig_IsComplement(pObj) );
+    assert( Aig_ObjIsNode(pObj) );
+    assert( iFrame == 0 || p->nWordsFrame < p->nWordsTotal );
+    // get hold of the simulation information
+    pSims  = Ssw_ObjSim(p, pObj->Id) + p->nWordsFrame * iFrame;
+    pSims0 = Ssw_ObjSim(p, Aig_ObjFanin0(pObj)->Id) + p->nWordsFrame * iFrame;
+    pSims1 = Ssw_ObjSim(p, Aig_ObjFanin1(pObj)->Id) + p->nWordsFrame * iFrame;
+    // get complemented attributes of the children using their random info
+    fCompl  = pObj->fPhase;
+    fCompl0 = Aig_ObjPhaseReal(Aig_ObjChild0(pObj));
+    fCompl1 = Aig_ObjPhaseReal(Aig_ObjChild1(pObj));
+    // simulate
+    if ( fCompl0 && fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = (pSims0[i] | pSims1[i]);
+        else
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = ~(pSims0[i] | pSims1[i]);
+    }
+    else if ( fCompl0 && !fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = (pSims0[i] | ~pSims1[i]);
+        else
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = (~pSims0[i] & pSims1[i]);
+    }
+    else if ( !fCompl0 && fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = (~pSims0[i] | pSims1[i]);
+        else
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = (pSims0[i] & ~pSims1[i]);
+    }
+    else // if ( !fCompl0 && !fCompl1 )
+    {
+        if ( fCompl )
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = ~(pSims0[i] & pSims1[i]);
+        else
+            for ( i = 0; i < p->nWordsFrame; i++ )
+                pSims[i] = (pSims0[i] & pSims1[i]);
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlNodesCompareInFrame( Ssw_Sml_t * p, Aig_Obj_t * pObj0, Aig_Obj_t * pObj1, int iFrame0, int iFrame1 )
+{
+    unsigned * pSims0, * pSims1;
+    int i;
+    assert( !Aig_IsComplement(pObj0) );
+    assert( !Aig_IsComplement(pObj1) );
+    assert( iFrame0 == 0 || p->nWordsFrame < p->nWordsTotal );
+    assert( iFrame1 == 0 || p->nWordsFrame < p->nWordsTotal );
+    // get hold of the simulation information
+    pSims0  = Ssw_ObjSim(p, pObj0->Id) + p->nWordsFrame * iFrame0;
+    pSims1  = Ssw_ObjSim(p, pObj1->Id) + p->nWordsFrame * iFrame1;
+    // compare
+    for ( i = 0; i < p->nWordsFrame; i++ )
+        if ( pSims0[i] != pSims1[i] )
+            return 0;
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlNodeCopyFanin( Ssw_Sml_t * p, Aig_Obj_t * pObj, int iFrame )
+{
+    unsigned * pSims, * pSims0;
+    int fCompl, fCompl0, i;
+    assert( !Aig_IsComplement(pObj) );
+    assert( Aig_ObjIsPo(pObj) );
+    assert( iFrame == 0 || p->nWordsFrame < p->nWordsTotal );
+    // get hold of the simulation information
+    pSims  = Ssw_ObjSim(p, pObj->Id) + p->nWordsFrame * iFrame;
+    pSims0 = Ssw_ObjSim(p, Aig_ObjFanin0(pObj)->Id) + p->nWordsFrame * iFrame;
+    // get complemented attributes of the children using their random info
+    fCompl  = pObj->fPhase;
+    fCompl0 = Aig_ObjPhaseReal(Aig_ObjChild0(pObj));
+    // copy information as it is
+    if ( fCompl0 )
+        for ( i = 0; i < p->nWordsFrame; i++ )
+            pSims[i] = ~pSims0[i];
+    else
+        for ( i = 0; i < p->nWordsFrame; i++ )
+            pSims[i] = pSims0[i];
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates one node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlNodeTransferNext( Ssw_Sml_t * p, Aig_Obj_t * pOut, Aig_Obj_t * pIn, int iFrame )
+{
+    unsigned * pSims0, * pSims1;
+    int i;
+    assert( !Aig_IsComplement(pOut) );
+    assert( !Aig_IsComplement(pIn) );
+    assert( Aig_ObjIsPo(pOut) );
+    assert( Aig_ObjIsPi(pIn) );
+    assert( iFrame == 0 || p->nWordsFrame < p->nWordsTotal );
+    // get hold of the simulation information
+    pSims0 = Ssw_ObjSim(p, pOut->Id) + p->nWordsFrame * iFrame;
+    pSims1 = Ssw_ObjSim(p, pIn->Id) + p->nWordsFrame * (iFrame+1);
+    // copy information as it is
+    for ( i = 0; i < p->nWordsFrame; i++ )
+        pSims1[i] = pSims0[i];
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Check if any of the POs becomes non-constant.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlCheckNonConstOutputs( Ssw_Sml_t * p )
+{
+    Aig_Obj_t * pObj;
+    int i;
+    Saig_ManForEachPo( p->pAig, pObj, i )
+        if ( !Ssw_SmlNodeIsZero(p, pObj) )
+            return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Simulates AIG manager.]
+
+  Description [Assumes that the PI simulation info is attached.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlSimulateOne( Ssw_Sml_t * p )
+{
+    Aig_Obj_t * pObj, * pObjLi, * pObjLo;
+    int f, i, clk;
+clk = clock();
+    for ( f = 0; f < p->nFrames; f++ )
+    {
+        // simulate the nodes
+        Aig_ManForEachNode( p->pAig, pObj, i )
+            Ssw_SmlNodeSimulate( p, pObj, f );
+        // copy simulation info into outputs
+        Saig_ManForEachPo( p->pAig, pObj, i )
+            Ssw_SmlNodeCopyFanin( p, pObj, f );
+        // quit if this is the last timeframe
+        if ( f == p->nFrames - 1 )
+            break;
+        // copy simulation info into outputs
+        Saig_ManForEachLi( p->pAig, pObj, i )
+            Ssw_SmlNodeCopyFanin( p, pObj, f );
+        // copy simulation info into the inputs
+        Saig_ManForEachLiLo( p->pAig, pObjLi, pObjLo, i )
+            Ssw_SmlNodeTransferNext( p, pObjLi, pObjLo, f );
+    }
+p->timeSim += clock() - clk;
+p->nSimRounds++;
+}
+
+
+#if 0
+
+/**Function*************************************************************
+
+  Synopsis    [Resimulates fraiging manager after finding a counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlResimulate( Ssw_Man_t * p )
+{
+    int nChanges, clk;
+    Ssw_SmlAssignDist1( p, p->pPatWords );
+    Ssw_SmlSimulateOne( p );
+//    if ( p->pPars->fPatScores )
+//        Ssw_CleanPatScores( p );
+    if ( p->pPars->fProve && Ssw_SmlCheckOutput(p) )
+        return;
+clk = clock();
+    nChanges = Ssw_ClassesRefine( p->pCla, 1 );
+    nChanges += Ssw_ClassesRefine1( p->pCla, 1, NULL );
+    if ( p->pCla->vImps )
+        nChanges += Ssw_ImpRefineUsingCex( p, p->pCla->vImps );
+    if ( p->vOneHots )
+        nChanges += Ssw_OneHotRefineUsingCex( p, p->vOneHots );
+p->timeRef += clock() - clk;
+    if ( !p->pPars->nFramesK && nChanges < 1 )
+        printf( "Error: A counter-example did not refine classes!\n" );
+//    assert( nChanges >= 1 );
+//printf( "Refined classes = %5d.   Changes = %4d.\n", Vec_PtrSize(p->vClasses), nChanges );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs simulation of the manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlSimulate( Ssw_Man_t * p, int fInit )
+{
+    int fVerbose = 0;
+    int nChanges, nClasses, clk;
+    assert( !fInit || Aig_ManRegNum(p->pAig) );
+    // start the classes
+    Ssw_SmlInitialize( p, fInit );
+    Ssw_SmlSimulateOne( p );
+    if ( p->pPars->fProve && Ssw_SmlCheckOutput(p) )
+        return;
+    Ssw_ClassesPrepare( p->pCla, p->pPars->fLatchCorr, 0 );
+//    Ssw_ClassesPrint( p->pCla, 0 );
+if ( fVerbose )
+printf( "Starting classes = %5d.   Lits = %6d.\n", Vec_PtrSize(p->pCla->vClasses), Ssw_ClassesCountLits(p->pCla) );
+
+//return;
+
+    // refine classes by walking 0/1 patterns
+    Ssw_SmlSavePattern0( p, fInit );
+    Ssw_SmlAssignDist1( p, p->pPatWords );
+    Ssw_SmlSimulateOne( p );
+    if ( p->pPars->fProve && Ssw_SmlCheckOutput(p) )
+        return;
+clk = clock();
+    nChanges = Ssw_ClassesRefine( p->pCla, 1 );
+    nChanges += Ssw_ClassesRefine1( p->pCla, 1, NULL );
+p->timeRef += clock() - clk;
+if ( fVerbose )
+printf( "Refined classes  = %5d.   Changes = %4d.   Lits = %6d.\n", Vec_PtrSize(p->pCla->vClasses), nChanges, Ssw_ClassesCountLits(p->pCla) );
+    Ssw_SmlSavePattern1( p, fInit );
+    Ssw_SmlAssignDist1( p, p->pPatWords );
+    Ssw_SmlSimulateOne( p );
+    if ( p->pPars->fProve && Ssw_SmlCheckOutput(p) )
+        return;
+clk = clock();
+    nChanges = Ssw_ClassesRefine( p->pCla, 1 );
+    nChanges += Ssw_ClassesRefine1( p->pCla, 1, NULL );
+p->timeRef += clock() - clk;
+
+if ( fVerbose )
+printf( "Refined classes  = %5d.   Changes = %4d.   Lits = %6d.\n", Vec_PtrSize(p->pCla->vClasses), nChanges, Ssw_ClassesCountLits(p->pCla) );
+    // refine classes by random simulation
+    do {
+        Ssw_SmlInitialize( p, fInit );
+        Ssw_SmlSimulateOne( p );
+        nClasses = Vec_PtrSize(p->pCla->vClasses);
+        if ( p->pPars->fProve && Ssw_SmlCheckOutput(p) )
+            return;
+clk = clock();
+        nChanges = Ssw_ClassesRefine( p->pCla, 1 );
+        nChanges += Ssw_ClassesRefine1( p->pCla, 1, NULL );
+p->timeRef += clock() - clk;
+if ( fVerbose )
+printf( "Refined classes  = %5d.   Changes = %4d.   Lits = %6d.\n", Vec_PtrSize(p->pCla->vClasses), nChanges, Ssw_ClassesCountLits(p->pCla) );
+    } while ( (double)nChanges / nClasses > p->pPars->dSimSatur );
+
+//    if ( p->pPars->fVerbose )
+//    printf( "Consts = %6d. Classes = %6d. Literals = %6d.\n", 
+//        Vec_PtrSize(p->pCla->vClasses1), Vec_PtrSize(p->pCla->vClasses), Ssw_ClassesCountLits(p->pCla) );
+//    Ssw_ClassesPrint( p->pCla, 0 );
+}
+ 
+#endif
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates simulation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ssw_Sml_t * Ssw_SmlStart( Aig_Man_t * pAig, int nPref, int nFrames, int nWordsFrame )
+{
+    Ssw_Sml_t * p;
+    p = (Ssw_Sml_t *)malloc( sizeof(Ssw_Sml_t) + sizeof(unsigned) * Aig_ManObjNumMax(pAig) * (nPref + nFrames) * nWordsFrame );
+    memset( p, 0, sizeof(Ssw_Sml_t) + sizeof(unsigned) * (nPref + nFrames) * nWordsFrame );
+    p->pAig        = pAig;
+    p->nPref       = nPref;
+    p->nFrames     = nPref + nFrames;
+    p->nWordsFrame = nWordsFrame;
+    p->nWordsTotal = (nPref + nFrames) * nWordsFrame;
+    p->nWordsPref  = nPref * nWordsFrame;
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Deallocates simulation manager.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlStop( Ssw_Sml_t * p )
+{
+    free( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Performs simulation of the uninitialized circuit.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ssw_Sml_t * Ssw_SmlSimulateComb( Aig_Man_t * pAig, int nWords )
+{
+    Ssw_Sml_t * p;
+    p = Ssw_SmlStart( pAig, 0, 1, nWords );
+    Ssw_SmlInitialize( p, 0 );
+    Ssw_SmlSimulateOne( p );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Performs simulation of the initialized circuit.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ssw_Sml_t * Ssw_SmlSimulateSeq( Aig_Man_t * pAig, int nPref, int nFrames, int nWords )
+{
+    Ssw_Sml_t * p;
+    p = Ssw_SmlStart( pAig, nPref, nFrames, nWords );
+    Ssw_SmlInitialize( p, 1 );
+    Ssw_SmlSimulateOne( p );
+    p->fNonConstOut = Ssw_SmlCheckNonConstOutputs( p );
+    return p;
+}
+
+
+
+/**Function*************************************************************
+
+  Synopsis    [Allocates a counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ssw_Cex_t * Ssw_SmlAllocCounterExample( int nRegs, int nRealPis, int nFrames )
+{
+    Ssw_Cex_t * pCex;
+    int nWords = Aig_BitWordNum( nRegs + nRealPis * nFrames );
+    pCex = (Ssw_Cex_t *)malloc( sizeof(Ssw_Cex_t) + sizeof(unsigned) * nWords );
+    memset( pCex, 0, sizeof(Ssw_Cex_t) + sizeof(unsigned) * nWords );
+    pCex->nRegs  = nRegs;
+    pCex->nPis   = nRealPis;
+    pCex->nBits  = nRegs + nRealPis * nFrames;
+    return pCex;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Frees the counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlFreeCounterExample( Ssw_Cex_t * pCex )
+{
+    free( pCex );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Resimulates the counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlRunCounterExample( Aig_Man_t * pAig, Ssw_Cex_t * p )
+{
+    Ssw_Sml_t * pSml;
+    Aig_Obj_t * pObj;
+    int RetValue, i, k, iBit;
+    assert( Aig_ManRegNum(pAig) > 0 );
+    assert( Aig_ManRegNum(pAig) < Aig_ManPiNum(pAig) );
+    // start a new sequential simulator
+    pSml = Ssw_SmlStart( pAig, 0, p->iFrame+1, 1 );
+    // assign simulation info for the registers
+    iBit = 0;
+    Saig_ManForEachLo( pAig, pObj, i )
+        Ssw_SmlAssignConst( pSml, pObj, Aig_InfoHasBit(p->pData, iBit++), 0 );
+    // assign simulation info for the primary inputs
+    for ( i = 0; i <= p->iFrame; i++ )
+        Saig_ManForEachPi( pAig, pObj, k )
+            Ssw_SmlAssignConst( pSml, pObj, Aig_InfoHasBit(p->pData, iBit++), i );
+    assert( iBit == p->nBits );
+    // run random simulation
+    Ssw_SmlSimulateOne( pSml );
+    // check if the given output has failed
+    RetValue = !Ssw_SmlNodeIsZero( pSml, Aig_ManPo(pAig, p->iPo) );
+    Ssw_SmlStop( pSml );
+    return RetValue;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Creates sequential counter-example from the simulation info.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ssw_Cex_t * Ssw_SmlGetCounterExample( Ssw_Sml_t * p )
+{
+    Ssw_Cex_t * pCex;
+    Aig_Obj_t * pObj;
+    unsigned * pSims;
+    int iPo, iFrame, iBit, i, k;
+
+    // make sure the simulation manager has it
+    assert( p->fNonConstOut );
+
+    // find the first output that failed
+    iPo = -1;
+    iBit = -1;
+    iFrame = -1;
+    Saig_ManForEachPo( p->pAig, pObj, iPo )
+    {
+        if ( Ssw_SmlNodeIsZero(p, pObj) )
+            continue;
+        pSims = Ssw_ObjSim( p, pObj->Id );
+        for ( i = p->nWordsPref; i < p->nWordsTotal; i++ )
+            if ( pSims[i] )
+            {
+                iFrame = i / p->nWordsFrame;
+                iBit = 32 * (i % p->nWordsFrame) + Aig_WordFindFirstBit( pSims[i] );
+                break;
+            }
+        break;
+    }
+    assert( iPo < Aig_ManPoNum(p->pAig)-Aig_ManRegNum(p->pAig) );
+    assert( iFrame < p->nFrames );
+    assert( iBit < 32 * p->nWordsFrame );
+
+    // allocate the counter example
+    pCex = Ssw_SmlAllocCounterExample( Aig_ManRegNum(p->pAig), Aig_ManPiNum(p->pAig) - Aig_ManRegNum(p->pAig), iFrame + 1 );
+    pCex->iPo    = iPo;
+    pCex->iFrame = iFrame;
+
+    // copy the bit data
+    Saig_ManForEachLo( p->pAig, pObj, k )
+    {
+        pSims = Ssw_ObjSim( p, pObj->Id );
+        if ( Aig_InfoHasBit( pSims, iBit ) )
+            Aig_InfoSetBit( pCex->pData, k );
+    }
+    for ( i = 0; i <= iFrame; i++ )
+    {
+        Saig_ManForEachPi( p->pAig, pObj, k )
+        {
+            pSims = Ssw_ObjSim( p, pObj->Id );
+            if ( Aig_InfoHasBit( pSims, 32 * p->nWordsFrame * i + iBit ) )
+                Aig_InfoSetBit( pCex->pData, pCex->nRegs + pCex->nPis * i + k );
+        }
+    }
+    // verify the counter example
+    if ( !Ssw_SmlRunCounterExample( p->pAig, pCex ) )
+    {
+        printf( "Ssw_SmlGetCounterExample(): Counter-example is invalid.\n" );
+        Ssw_SmlFreeCounterExample( pCex );
+        pCex = NULL;
+    }
+    return pCex;
+}
+ 
+/**Function*************************************************************
+
+  Synopsis    [Generates seq counter-example from the combinational one.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ssw_Cex_t * Ssw_SmlCopyCounterExample( Aig_Man_t * pAig, Aig_Man_t * pFrames, int * pModel )
+{
+    Ssw_Cex_t * pCex;
+    Aig_Obj_t * pObj;
+    int i, nFrames, nTruePis, nTruePos, iPo, iFrame;
+    // get the number of frames
+    assert( Aig_ManRegNum(pAig) > 0 );
+    assert( Aig_ManRegNum(pFrames) == 0 );
+    nTruePis = Aig_ManPiNum(pAig)-Aig_ManRegNum(pAig);
+    nTruePos = Aig_ManPoNum(pAig)-Aig_ManRegNum(pAig);
+    nFrames = Aig_ManPiNum(pFrames) / nTruePis;
+    assert( nTruePis * nFrames == Aig_ManPiNum(pFrames) );
+    assert( nTruePos * nFrames == Aig_ManPoNum(pFrames) );
+    // find the PO that failed
+    iPo = -1;
+    iFrame = -1;
+    Aig_ManForEachPo( pFrames, pObj, i )
+        if ( pObj->Id == pModel[Aig_ManPiNum(pFrames)] )
+        {
+            iPo = i % nTruePos;
+            iFrame = i / nTruePos;
+            break;
+        }
+    assert( iPo >= 0 );
+    // allocate the counter example
+    pCex = Ssw_SmlAllocCounterExample( Aig_ManRegNum(pAig), nTruePis, iFrame + 1 );
+    pCex->iPo    = iPo;
+    pCex->iFrame = iFrame;
+
+    // copy the bit data
+    for ( i = 0; i < Aig_ManPiNum(pFrames); i++ )
+    {
+        if ( pModel[i] )
+            Aig_InfoSetBit( pCex->pData, pCex->nRegs + i );
+        if ( pCex->nRegs + i == pCex->nBits - 1 )
+            break;
+    }
+
+    // verify the counter example
+    if ( !Ssw_SmlRunCounterExample( pAig, pCex ) )
+    {
+        printf( "Ssw_SmlGetCounterExample(): Counter-example is invalid.\n" );
+        Ssw_SmlFreeCounterExample( pCex );
+        pCex = NULL;
+    }
+    return pCex;
+
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Make the trivial counter-example for the trivially asserted output.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Ssw_Cex_t * Ssw_SmlTrivCounterExample( Aig_Man_t * pAig, int iFrameOut )
+{
+    Ssw_Cex_t * pCex;
+    int nTruePis, nTruePos, iPo, iFrame;
+    assert( Aig_ManRegNum(pAig) > 0 );
+    nTruePis = Aig_ManPiNum(pAig)-Aig_ManRegNum(pAig);
+    nTruePos = Aig_ManPoNum(pAig)-Aig_ManRegNum(pAig);
+    iPo = iFrameOut % nTruePos;
+    iFrame = iFrameOut / nTruePos;
+    // allocate the counter example
+    pCex = Ssw_SmlAllocCounterExample( Aig_ManRegNum(pAig), nTruePis, iFrame + 1 );
+    pCex->iPo    = iPo;
+    pCex->iFrame = iFrame;
+    return pCex;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Resimulates the counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Ssw_SmlWriteCounterExample( FILE * pFile, Aig_Man_t * pAig, Ssw_Cex_t * p )
+{
+    Ssw_Sml_t * pSml;
+    Aig_Obj_t * pObj;
+    int RetValue, i, k, iBit;
+    unsigned * pSims;
+    assert( Aig_ManRegNum(pAig) > 0 );
+    assert( Aig_ManRegNum(pAig) < Aig_ManPiNum(pAig) );
+    // start a new sequential simulator
+    pSml = Ssw_SmlStart( pAig, 0, p->iFrame+1, 1 );
+    // assign simulation info for the registers
+    iBit = 0;
+    Saig_ManForEachLo( pAig, pObj, i )
+//        Ssw_SmlAssignConst( pSml, pObj, Aig_InfoHasBit(p->pData, iBit++), 0 );
+        Ssw_SmlAssignConst( pSml, pObj, 0, 0 );
+    // assign simulation info for the primary inputs
+    iBit = p->nRegs;
+    for ( i = 0; i <= p->iFrame; i++ )
+        Saig_ManForEachPi( pAig, pObj, k )
+            Ssw_SmlAssignConst( pSml, pObj, Aig_InfoHasBit(p->pData, iBit++), i );
+    assert( iBit == p->nBits );
+    // run random simulation
+    Ssw_SmlSimulateOne( pSml );
+    // check if the given output has failed
+    RetValue = !Ssw_SmlNodeIsZero( pSml, Aig_ManPo(pAig, p->iPo) );
+
+    // write the output file
+    for ( i = 0; i <= p->iFrame; i++ )
+    {
+/*
+        Saig_ManForEachLo( pAig, pObj, k )
+        {
+            pSims = Ssw_ObjSim(pSml, pObj->Id);
+            fprintf( pFile, "%d", (int)(pSims[i] != 0) );
+        }
+        fprintf( pFile, " " );
+*/
+        Saig_ManForEachPi( pAig, pObj, k )
+        {
+            pSims = Ssw_ObjSim(pSml, pObj->Id);
+            fprintf( pFile, "%d", (int)(pSims[i] != 0) );
+        }
+/*
+        fprintf( pFile, " " );
+        Saig_ManForEachPo( pAig, pObj, k )
+        {
+            pSims = Ssw_ObjSim(pSml, pObj->Id);
+            fprintf( pFile, "%d", (int)(pSims[i] != 0) );
+        }
+        fprintf( pFile, " " );
+        Saig_ManForEachLi( pAig, pObj, k )
+        {
+            pSims = Ssw_ObjSim(pSml, pObj->Id);
+            fprintf( pFile, "%d", (int)(pSims[i] != 0) );
+        }
+*/
+        fprintf( pFile, "\n" );
+    }
+
+    Ssw_SmlStop( pSml );
+    return RetValue;
+}
+
+
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+
diff --git a/src/aig/ssw/sswSimSat.c b/src/aig/ssw/sswSimSat.c
index 868a016b..547755f0 100644
--- a/src/aig/ssw/sswSimSat.c
+++ b/src/aig/ssw/sswSimSat.c
@@ -241,7 +241,60 @@ void Ssw_ManResimulateCexTotal( Ssw_Man_t * p, Aig_Obj_t * pCand, Aig_Obj_t * pR
                      & ( Aig_ObjFanin1(pObj)->fMarkB ^ Aig_ObjFaninC1(pObj) );
     // check equivalence classes
     RetValue1 = Ssw_ClassesRefineConst1( p->ppClasses, 0 );
-    RetValue2 = Ssw_ClassesRefine( p->ppClasses );
+    RetValue2 = Ssw_ClassesRefine( p->ppClasses, 0 );
+    // make sure refinement happened
+    if ( Aig_ObjIsConst1(pRepr) )
+        assert( RetValue1 );
+    else
+        assert( RetValue2 );
+p->timeSimSat += clock() - clk;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Copy pattern from the solver into the internal storage.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_SmlSavePatternAig( Ssw_Man_t * p, int f )
+{
+    Aig_Obj_t * pObj;
+    int i;
+    memset( p->pPatWords, 0, sizeof(unsigned) * p->nPatWords );
+    Aig_ManForEachPi( p->pAig, pObj, i )
+        if ( Ssw_ManOriginalPiValue( p, pObj, f ) )
+            Aig_InfoSetBit( p->pPatWords, i );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Handle the counter-example.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Ssw_ManResimulateCexTotalSim( Ssw_Man_t * p, Aig_Obj_t * pCand, Aig_Obj_t * pRepr, int f )
+{
+    int RetValue1, RetValue2, clk = clock();
+    // save the counter-example
+    Ssw_SmlSavePatternAig( p, f );
+    // set the PI simulation information
+    Ssw_SmlAssignDist1Plus( p->pSml, p->pPatWords );
+    // simulate internal nodes
+    Ssw_SmlSimulateOne( p->pSml );
+    // check equivalence classes
+    RetValue1 = Ssw_ClassesRefineConst1( p->ppClasses, 1 );
+    RetValue2 = Ssw_ClassesRefine( p->ppClasses, 1 );
     // make sure refinement happened
     if ( Aig_ObjIsConst1(pRepr) )
         assert( RetValue1 );
diff --git a/src/aig/ssw/sswSweep.c b/src/aig/ssw/sswSweep.c
index 0630de56..7c99fad2 100644
--- a/src/aig/ssw/sswSweep.c
+++ b/src/aig/ssw/sswSweep.c
@@ -74,16 +74,12 @@ void Ssw_ManSweepNode( Ssw_Man_t * p, Aig_Obj_t * pObj, int f )
                 p->pSat->model.ptr[iVar] = (int)(p->pPars->fPolarFlip? 0 : (pObj->fPhase? l_True : l_False));
                 p->pSat->model.size = p->pSat->size;
             }
-        p->nStragers++;
+        p->nStrangers++;
         return;
     }
     // if the fraiged nodes are the same, return
     if ( Aig_Regular(pObjFraig) == Aig_Regular(pObjReprFraig) )
-    {
-        // remember the proved equivalence
-//        p->pReprsProved[ pObj->Id ] = pObjRepr;
         return;
-    }
 //    assert( Aig_Regular(pObjFraig) != Aig_ManConst1(p->pFrames) );
     if ( Aig_Regular(pObjFraig) != Aig_ManConst1(p->pFrames) )
         RetValue = Ssw_NodesAreEquiv( p, Aig_Regular(pObjReprFraig), Aig_Regular(pObjFraig) );
@@ -92,7 +88,7 @@ void Ssw_ManSweepNode( Ssw_Man_t * p, Aig_Obj_t * pObj, int f )
 
     if ( RetValue == -1 ) // timed out
     {
-        assert( 0 );
+//        assert( 0 );
         Ssw_ClassesRemoveNode( p->ppClasses, pObj );
         p->fRefined = 1;
         return;
@@ -101,13 +97,12 @@ void Ssw_ManSweepNode( Ssw_Man_t * p, Aig_Obj_t * pObj, int f )
     {
         pObjFraig2 = Aig_NotCond( pObjReprFraig, pObj->fPhase ^ pObjRepr->fPhase );
         Ssw_ObjSetFraig( p, pObj, f, pObjFraig2 );
-        // remember the proved equivalence
-//        p->pReprsProved[ pObj->Id ] = pObjRepr;
         return;
     }
     // disproved the equivalence
 //    Ssw_ManResimulateCex( p, pObj, pObjRepr, f );
-    Ssw_ManResimulateCexTotal( p, pObj, pObjRepr, f );
+//    Ssw_ManResimulateCexTotal( p, pObj, pObjRepr, f );
+    Ssw_ManResimulateCexTotalSim( p, pObj, pObjRepr, f );
     assert( Aig_ObjRepr( p->pAig, pObj ) != pObjRepr );
     p->fRefined = 1;
 }
@@ -126,7 +121,7 @@ void Ssw_ManSweepNode( Ssw_Man_t * p, Aig_Obj_t * pObj, int f )
 int Ssw_ManSweepBmc( Ssw_Man_t * p )
 {
     Bar_Progress_t * pProgress = NULL;
-    Aig_Obj_t * pObj, * pObjNew;
+    Aig_Obj_t * pObj, * pObjNew, * pObjLi, * pObjLo;
     int i, f, clk;
 clk = clock();
 
@@ -154,6 +149,12 @@ clk = clock();
             Ssw_ObjSetFraig( p, pObj, f, pObjNew );
             Ssw_ManSweepNode( p, pObj, f );
         }
+        // quit if this is the last timeframe
+        if ( f == p->pPars->nFramesK - 1 )
+            break;
+        // transfer latch input to the latch outputs 
+        Saig_ManForEachLiLo( p->pAig, pObjLi, pObjLo, i )
+            Ssw_ObjSetFraig( p, pObjLo, f+1, Ssw_ObjChild0Fra(p, pObjLi,f) );
     }
     if ( p->pPars->fVerbose )
         Bar_ProgressStop( pProgress );
@@ -223,7 +224,7 @@ p->timeReduce += clock() - clk;
         if ( Saig_ObjIsLo(p->pAig, pObj) )
             Ssw_ManSweepNode( p, pObj, f );
         else if ( Aig_ObjIsNode(pObj) )
-        {
+        { 
             pObjNew = Aig_And( p->pFrames, Ssw_ObjChild0Fra(p, pObj, f), Ssw_ObjChild1Fra(p, pObj, f) );
             Ssw_ObjSetFraig( p, pObj, f, pObjNew );
             Ssw_ManSweepNode( p, pObj, f );
diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index 8df6f066..0125ae9e 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -7681,7 +7681,7 @@ int Abc_CommandTest( Abc_Frame_t * pAbc, int argc, char ** argv )
 {
     FILE * pOut, * pErr;
     Abc_Ntk_t * pNtk;
-//    Abc_Ntk_t * pNtkRes;
+    Abc_Ntk_t * pNtkRes;
     int c;
     int fBmc;
     int nFrames;
@@ -7700,7 +7700,7 @@ int Abc_CommandTest( Abc_Frame_t * pAbc, int argc, char ** argv )
     extern Abc_Ntk_t * Abc_NtkDarToCnf( Abc_Ntk_t * pNtk, char * pFileName );
     extern Abc_Ntk_t * Abc_NtkFilter( Abc_Ntk_t * pNtk );
 //    extern Abc_Ntk_t * Abc_NtkDarRetime( Abc_Ntk_t * pNtk, int nStepsMax, int fVerbose );
-//    extern Abc_Ntk_t * Abc_NtkPcmTest( Abc_Ntk_t * pNtk, int fVerbose );
+    extern Abc_Ntk_t * Abc_NtkPcmTest( Abc_Ntk_t * pNtk, int fVerbose );
     extern Abc_Ntk_t * Abc_NtkDarHaigRecord( Abc_Ntk_t * pNtk, int nIters, int nSteps, int fRetimingOnly, int fAddBugs, int fUseCnf, int fVerbose );
 //    extern void Abc_NtkDarTestBlif( char * pFileName );
 //    extern Abc_Ntk_t * Abc_NtkDarPartition( Abc_Ntk_t * pNtk );
@@ -7869,9 +7869,10 @@ int Abc_CommandTest( Abc_Frame_t * pAbc, int argc, char ** argv )
 */
 
 
-/*
+
 //    pNtkRes = Abc_NtkDar( pNtk );
-//    pNtkRes = Abc_NtkDarRetime( pNtk, nLevels, 1 );
+//    pNtkRes = Abc_NtkDarRetime( pNtk, nLevels, 1 ); 
+//    pNtkRes = Abc_NtkPcmTestAig( pNtk, fVerbose );
     pNtkRes = Abc_NtkPcmTest( pNtk, fVerbose );
 //    pNtkRes = NULL;
     if ( pNtkRes == NULL )
@@ -7882,7 +7883,7 @@ int Abc_CommandTest( Abc_Frame_t * pAbc, int argc, char ** argv )
     // replace the current network
     Abc_FrameReplaceCurrentNetwork( pAbc, pNtkRes );
     return 0;
-*/
+
 
 
 //    Abc_NtkDarClau( pNtk, nFrames, nLevels, fBmc, fVerbose, fVeryVerbose );
diff --git a/src/base/abci/abcDar.c b/src/base/abci/abcDar.c
index a0284a17..c430137c 100644
--- a/src/base/abci/abcDar.c
+++ b/src/base/abci/abcDar.c
@@ -119,6 +119,7 @@ Aig_Man_t * Abc_NtkToDar( Abc_Ntk_t * pNtk, int fExors, int fRegisters )
     Abc_NtkForEachCo( pNtk, pObj, i )
         Aig_ObjCreatePo( pMan, (Aig_Obj_t *)Abc_ObjChild0Copy(pObj) );
     // complement the 1-valued registers
+    Aig_ManSetRegNum( pMan, Abc_NtkLatchNum(pNtk) );
     if ( fRegisters )
         Aig_ManForEachLiSeq( pMan, pObjNew, i )
             if ( Abc_LatchIsInit1(Abc_ObjFanout0(Abc_NtkCo(pNtk,i))) )
diff --git a/src/map/mio/mio.c b/src/map/mio/mio.c
index e0000c38..37ba82c2 100644
--- a/src/map/mio/mio.c
+++ b/src/map/mio/mio.c
@@ -206,6 +206,9 @@ int Mio_CommandReadLibrary( Abc_Frame_t * pAbc, int argc, char **argv )
 usage:
     fprintf( pErr, "usage: read_library [-vh]\n");
     fprintf( pErr, "\t         read the library from a genlib file\n" );  
+    fprintf( pErr, "\t         (if the library contains more than one gate\n" );  
+    fprintf( pErr, "\t         with the same Boolean function, only the first gate\n" );  
+    fprintf( pErr, "\t         in the order of their appearance in the file is used)\n" );  
     fprintf( pErr, "\t-h     : enable verbose output\n");
     return 1;       /* error exit */
 }