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1 files changed, 912 insertions, 0 deletions

diff --git a/src/aig/fra/fraClaus.c b/src/aig/fra/fraClaus.c
new file mode 100644
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+++ b/src/aig/fra/fraClaus.c
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+/**CFile****************************************************************
+
+  FileName    [fraClaus.c]
+
+  SystemName  [ABC: Logic synthesis and verification system.]
+
+  PackageName [New FRAIG package.]
+
+  Synopsis    [Induction with clause strengthening.]
+
+  Author      [Alan Mishchenko]
+  
+  Affiliation [UC Berkeley]
+
+  Date        [Ver. 1.0. Started - June 30, 2007.]
+
+  Revision    [$Id: fraClau.c,v 1.00 2007/06/30 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "fra.h"
+#include "cnf.h"
+#include "satSolver.h"
+
+////////////////////////////////////////////////////////////////////////
+///                        DECLARATIONS                              ///
+////////////////////////////////////////////////////////////////////////
+
+typedef struct Clu_Man_t_    Clu_Man_t;
+struct Clu_Man_t_
+{
+    // parameters
+    int              nFrames;
+    int              nClausesMax;
+    int              fVerbose;
+    int              fVeryVerbose;
+    int              nSimWords;
+    int              nSimFrames;
+    // the network
+    Aig_Man_t *      pAig;
+    // SAT solvers
+    sat_solver *     pSatMain;
+    sat_solver *     pSatBmc;
+    // CNF for the test solver
+    Cnf_Dat_t *      pCnf;
+    // the counter example
+    Vec_Int_t *      vValues;
+    // clauses
+    Vec_Int_t *      vLits;
+    Vec_Int_t *      vClauses;
+    Vec_Int_t *      vCosts;
+    int              nClauses;
+    // counter-examples
+    Vec_Ptr_t *      vCexes;
+    int              nCexes;
+    int              nCexesAlloc;
+};
+
+////////////////////////////////////////////////////////////////////////
+///                     FUNCTION DEFINITIONS                         ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+  Synopsis    [Runs the SAT solver on the problem.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausRunBmc( Clu_Man_t * p )
+{
+    Aig_Obj_t * pObj;
+    int * pLits;
+    int nBTLimit = 0;
+    int i, RetValue;
+    pLits = ALLOC( int, p->nFrames + 1 );
+    // set the output literals
+    pObj = Aig_ManPo(p->pAig, 0);
+    for ( i = 0; i < p->nFrames; i++ )
+        pLits[i] = i * 2 * p->pCnf->nVars + toLitCond( p->pCnf->pVarNums[pObj->Id], 0 ); 
+    // try to solve the problem
+//    sat_solver_act_var_clear( p->pSatBmc );
+//    RetValue = sat_solver_solve( p->pSatBmc, NULL, NULL, (sint64)nBTLimit, (sint64)0, (sint64)0, (sint64)0 );
+    for ( i = 0; i < p->nFrames; i++ )
+    {
+        RetValue = sat_solver_solve( p->pSatBmc, pLits + i, pLits + i + 1, (sint64)nBTLimit, (sint64)0, (sint64)0, (sint64)0 );
+        if ( RetValue != l_False )
+        {
+            free( pLits );
+            return 0;
+        }
+    }
+    free( pLits );
+
+/*
+    // get the counter-example
+    assert( RetValue == l_True );
+    nVarsTot = p->nFrames * p->pCnf->nVars;
+    Aig_ManForEachObj( p->pAig, pObj, i )
+        Vec_IntWriteEntry( p->vValues, i, sat_solver_var_value(p->pSatBmc, nVarsTot + p->pCnf->pVarNums[i]) );
+*/
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Runs the SAT solver on the problem.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausRunSat( Clu_Man_t * p )
+{
+    int nBTLimit = 0;
+    Aig_Obj_t * pObj;
+    int * pLits;
+    int i, nVarsTot, RetValue;
+    pLits = ALLOC( int, p->nFrames + 1 );
+    // set the output literals
+    pObj = Aig_ManPo(p->pAig, 0);
+    for ( i = 0; i <= p->nFrames; i++ )
+        pLits[i] = i * 2 * p->pCnf->nVars + toLitCond( p->pCnf->pVarNums[pObj->Id], i != p->nFrames ); 
+    // try to solve the problem
+//    sat_solver_act_var_clear( p->pSatMain );
+//    RetValue = sat_solver_solve( p->pSatMain, NULL, NULL, (sint64)nBTLimit, (sint64)0, (sint64)0, (sint64)0 );
+    RetValue = sat_solver_solve( p->pSatMain, pLits, pLits + p->nFrames + 1, (sint64)nBTLimit, (sint64)0, (sint64)0, (sint64)0 );
+    free( pLits );
+    if ( RetValue == l_False )
+        return 1;
+    // get the counter-example
+    assert( RetValue == l_True );
+    nVarsTot = p->nFrames * p->pCnf->nVars;
+    Aig_ManForEachObj( p->pAig, pObj, i )
+        Vec_IntWriteEntry( p->vValues, i, sat_solver_var_value(p->pSatMain, nVarsTot + p->pCnf->pVarNums[i]) );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Runs the SAT solver on the problem.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausRunSat0( Clu_Man_t * p )
+{
+    int nBTLimit = 0;
+    Aig_Obj_t * pObj;
+    int Lits[2], RetValue;
+    pObj = Aig_ManPo(p->pAig, 0);
+    Lits[0] = toLitCond( p->pCnf->pVarNums[pObj->Id], 0 ); 
+    RetValue = sat_solver_solve( p->pSatMain, Lits, Lits + 1, (sint64)nBTLimit, (sint64)0, (sint64)0, (sint64)0 );
+    if ( RetValue == l_False )
+        return 1;
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Processes the clauses.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+/*
+int Fra_ClausProcessClausesCut( Clu_Man_t * p, Dar_Cut_t * pCut )
+{
+    unsigned * pSimsC[4], * pSimsS[4];
+    int pLits[4];
+    int i, b, k, iMint, uMask, RetValue, nLeaves, nWordsTotal, nCounter;
+    // compute parameters
+    nLeaves = pCut->nLeaves;
+    nWordsTotal = p->pComb->nWordsTotal;
+    assert( nLeaves > 1 && nLeaves < 5 );
+    assert( nWordsTotal == p->pSeq->nWordsTotal );
+    // get parameters
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+    {
+        pSimsC[i] = Fra_ObjSim( p->pComb, pCut->pLeaves[i] );
+        pSimsS[i] = Fra_ObjSim( p->pSeq,  pCut->pLeaves[i] );
+    }
+    // add combinational patterns
+    uMask = 0;
+    for ( i = 0; i < nWordsTotal; i++ )
+        for ( k = 0; k < 32; k++ )
+        {
+            iMint = 0;
+            for ( b = 0; b < nLeaves; b++ )
+                if ( pSimsC[b][i] & (1 << k) )
+                    iMint |= (1 << b);
+            uMask |= (1 << iMint);
+        }
+    // remove sequential patterns
+    for ( i = 0; i < nWordsTotal; i++ )
+        for ( k = 0; k < 32; k++ )
+        {
+            iMint = 0;
+            for ( b = 0; b < nLeaves; b++ )
+                if ( pSimsS[b][i] & (1 << k) )
+                    iMint |= (1 << b);
+            uMask &= ~(1 << iMint);
+        }
+    if ( uMask == 0 )
+        return 0;
+    // add clauses for the remaining patterns
+    nCounter = 0;
+    for ( i = 0; i < (1<<nLeaves); i++ )
+    {
+        if ( (uMask & (1 << i)) == 0 )
+            continue;
+        nCounter++;
+//        continue;
+
+        // add every third clause
+//        if ( (nCounter % 2) == 0 )
+//            continue;
+
+        for ( b = 0; b < nLeaves; b++ )
+            pLits[b] = toLitCond( p->pCnf->pVarNums[pCut->pLeaves[b]], (i&(1<<b)) );
+        // add the clause
+        RetValue = sat_solver_addclause( p->pSatMain, pLits, pLits + nLeaves );
+//        assert( RetValue == 1 );
+        if ( RetValue == 0 )
+        {
+            printf( "Already UNSAT after %d clauses.\n", nCounter );
+            return -1;
+        }
+    }
+    return nCounter;
+}
+*/
+
+
+/**Function*************************************************************
+
+  Synopsis    [Return combinations appearing in the cut.]
+
+  Description [This procedure is taken from "Hacker's Delight" by H.S.Warren.]
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void transpose32a( unsigned a[32] ) 
+{
+    int j, k;
+    unsigned long m, t;
+    for ( j = 16, m = 0x0000FFFF; j; j >>= 1, m ^= m << j ) 
+    {
+        for ( k = 0; k < 32; k = ((k | j) + 1) & ~j ) 
+        {
+            t = (a[k] ^ (a[k|j] >> j)) & m;
+            a[k] ^= t;
+            a[k|j] ^= (t << j);
+        }
+    }
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Return combinations appearing in the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausProcessClausesCut( Clu_Man_t * p, Fra_Sml_t * pSimMan, Dar_Cut_t * pCut, int * pScores )
+{
+    unsigned Matrix[32];
+    unsigned * pSims[4], uWord;
+    int nSeries, i, k, j;
+    // compute parameters
+    assert( pCut->nLeaves > 1 && pCut->nLeaves < 5 );
+    assert( pSimMan->nWordsTotal % 8 == 0 );
+    // get parameters
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+        pSims[i] = Fra_ObjSim( pSimMan, pCut->pLeaves[i] );
+    // add combinational patterns
+    memset( pScores, 0, sizeof(int) * 16 );
+    nSeries = pSimMan->nWordsTotal / 8;
+    for ( i = 0; i < nSeries; i++ )
+    {
+        memset( Matrix, 0, sizeof(unsigned) * 32 );
+        for ( k = 0; k < 8; k++ )
+            for ( j = 0; j < (int)pCut->nLeaves; j++ )
+                Matrix[31-(k*4+j)] = pSims[j][i*8+k];
+/*
+        for ( k = 0; k < 32; k++ )
+        {
+            Extra_PrintBinary( stdout, Matrix + k, 32 ); printf( "\n" );
+        }
+        printf( "\n" );
+*/
+        transpose32a( Matrix );
+/*
+        for ( k = 0; k < 32; k++ )
+        {
+            Extra_PrintBinary( stdout, Matrix + k, 32 ); printf( "\n" );
+        }
+        printf( "\n" );
+*/
+        for ( k = 0; k < 32; k++ )
+            for ( j = 0, uWord = Matrix[k]; j < 8; j++, uWord >>= 4 )
+                pScores[uWord & 0xF]++;
+    }
+    // collect patterns
+    uWord = 0;
+    for ( i = 0; i < 16; i++ )
+        if ( pScores[i] )
+            uWord |= (1 << i);
+//    Extra_PrintBinary( stdout, &uWord, 16 ); printf( "\n" );
+    return (int)uWord;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Return combinations appearing in the cut.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausProcessClausesCut2( Clu_Man_t * p, Fra_Sml_t * pSimMan, Dar_Cut_t * pCut, int * pScores )
+{
+    unsigned * pSims[4], uWord;
+    int iMint, i, k, b;
+    // compute parameters
+    assert( pCut->nLeaves > 1 && pCut->nLeaves < 5 );
+    assert( pSimMan->nWordsTotal % 8 == 0 );
+    // get parameters
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+        pSims[i] = Fra_ObjSim( pSimMan, pCut->pLeaves[i] );
+    // add combinational patterns
+    memset( pScores, 0, sizeof(int) * 16 );
+    for ( i = 0; i < pSimMan->nWordsTotal; i++ )
+        for ( k = 0; k < 32; k++ )
+        {
+            iMint = 0;
+            for ( b = 0; b < (int)pCut->nLeaves; b++ )
+                if ( pSims[b][i] & (1 << k) )
+                    iMint |= (1 << b);
+            pScores[iMint]++;
+        }
+    // collect patterns
+    uWord = 0;
+    for ( i = 0; i < 16; i++ )
+        if ( pScores[i] )
+            uWord |= (1 << i);
+//    Extra_PrintBinary( stdout, &uWord, 16 ); printf( "\n" );
+    return (int)uWord;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Processes the clauses.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fra_ClausRecordClause( Clu_Man_t * p, Dar_Cut_t * pCut, int iMint, int Cost )
+{
+    int i;
+    for ( i = 0; i < (int)pCut->nLeaves; i++ )
+        Vec_IntPush( p->vLits, toLitCond( p->pCnf->pVarNums[pCut->pLeaves[i]], (iMint&(1<<i)) ) );
+    Vec_IntPush( p->vClauses, Vec_IntSize(p->vLits) );
+    Vec_IntPush( p->vCosts, Cost );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Processes the clauses.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausProcessClauses( Clu_Man_t * p )
+{
+    Aig_MmFixed_t * pMemCuts;
+    Fra_Sml_t * pComb, * pSeq;
+    Aig_Obj_t * pObj;
+    Dar_Cut_t * pCut;
+    int Scores[16], uScores, i, k, j, clk, nCuts = 0;
+
+    // simulate the AIG
+clk = clock();
+    srand( 0xAABBAABB );
+    pSeq = Fra_SmlSimulateSeq( p->pAig, 0, p->nSimFrames, p->nSimWords/p->nSimFrames );
+    if ( pSeq->fNonConstOut )
+    {
+        printf( "Property failed after sequential simulation!\n" );
+        Fra_SmlStop( pSeq );
+        return 0;
+    }
+PRT( "Sim-seq", clock() - clk );
+
+    // generate cuts for all nodes, assign cost, and find best cuts
+clk = clock();
+    pMemCuts = Dar_ManComputeCuts( p->pAig, 10 );
+PRT( "Cuts   ", clock() - clk );
+
+    // collect sequential info for each cut
+clk = clock();
+    Aig_ManForEachNode( p->pAig, pObj, i )
+        Dar_ObjForEachCut( pObj, pCut, k )
+            if ( pCut->nLeaves > 1 )
+            {
+                pCut->uTruth = Fra_ClausProcessClausesCut( p, pSeq, pCut, Scores );
+//                uScores = Fra_ClausProcessClausesCut2( p, pSeq, pCut, Scores );
+//                if ( uScores != pCut->uTruth )
+//                {
+//                    int x = 0;
+//                }
+            }
+PRT( "Infoseq", clock() - clk );
+    Fra_SmlStop( pSeq );
+
+    // perform combinational simulation
+clk = clock();
+    srand( 0xAABBAABB );
+    pComb = Fra_SmlSimulateComb( p->pAig, p->nSimWords );
+PRT( "Sim-cmb", clock() - clk );
+
+    // collect combinational info for each cut
+clk = clock();
+    Aig_ManForEachNode( p->pAig, pObj, i )
+        Dar_ObjForEachCut( pObj, pCut, k )
+            if ( pCut->nLeaves > 1 )
+            {
+                nCuts++;
+                uScores = Fra_ClausProcessClausesCut( p, pComb, pCut, Scores );
+                uScores &= ~pCut->uTruth; pCut->uTruth = 0;
+                if ( uScores == 0 )
+                    continue;
+                // write the clauses
+                for ( j = 0; j < (1<<pCut->nLeaves); j++ )
+                    if ( uScores & (1 << j) )
+                        Fra_ClausRecordClause( p, pCut, j, Scores[j] );
+
+            }
+    Fra_SmlStop( pComb );
+    Aig_MmFixedStop( pMemCuts, 0 );
+PRT( "Infocmb", clock() - clk );
+
+    printf( "Node = %5d. Non-triv cuts = %7d. Clauses = %6d. Clause per cut = %6.2f.\n", 
+        Aig_ManNodeNum(p->pAig), nCuts, Vec_IntSize(p->vClauses), 1.0*Vec_IntSize(p->vClauses)/nCuts );
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts AIG into the SAT solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausBmcClauses( Clu_Man_t * p )
+{
+    int nBTLimit = 0;
+    int * pStart, nLitsTot, RetValue, Beg, End, Counter, i, k, f;
+/*
+    for ( i = 0; i < Vec_IntSize(p->vLits); i++ )
+        printf( "%d ", p->vLits->pArray[i] );
+    printf( "\n" );
+*/
+    // add the clauses
+    Counter = 0;
+    nLitsTot = 2 * p->pCnf->nVars;
+    for ( f = 0; f < p->nFrames; f++ )
+    {
+        Beg = 0;
+        Vec_IntForEachEntry( p->vClauses, End, i )
+        {
+            if ( Vec_IntEntry( p->vCosts, i ) == -1 )
+            {
+                Beg = End;
+                continue;
+            }
+            assert( Vec_IntEntry( p->vCosts, i ) > 0 );
+            assert( End - Beg < 5 );
+            pStart = Vec_IntArray(p->vLits);
+            for ( k = Beg; k < End; k++ )
+                pStart[k] = lit_neg( pStart[k] );
+            RetValue = sat_solver_solve( p->pSatBmc, pStart + Beg, pStart + End, (sint64)nBTLimit, (sint64)0, (sint64)0, (sint64)0 );
+            for ( k = Beg; k < End; k++ )
+                pStart[k] = lit_neg( pStart[k] );
+            if ( RetValue != l_False )
+            {
+                Beg = End;
+                Vec_IntWriteEntry( p->vCosts, i, -1 );
+                Counter++;
+                continue;
+            }
+/*
+            // add the clause
+            RetValue = sat_solver_addclause( p->pSatBmc, pStart + Beg, pStart + End );
+    //        assert( RetValue == 1 );
+            if ( RetValue == 0 )
+            {
+                printf( "Error: Solver is UNSAT after adding BMC clauses.\n" );
+                return -1;
+            }
+*/
+            Beg = End;
+
+            // simplify the solver
+            if ( p->pSatBmc->qtail != p->pSatBmc->qhead )
+            {
+                RetValue = sat_solver_simplify(p->pSatBmc);
+                assert( RetValue != 0 );
+                assert( p->pSatBmc->qtail == p->pSatBmc->qhead );
+            }
+        }
+        // increment literals
+        for ( i = 0; i < Vec_IntSize(p->vLits); i++ )
+            p->vLits->pArray[i] += nLitsTot;
+    }
+
+    // return clauses back to normal
+    nLitsTot = p->nFrames * nLitsTot;
+    for ( i = 0; i < Vec_IntSize(p->vLits); i++ )
+        p->vLits->pArray[i] -= nLitsTot;
+/*
+    for ( i = 0; i < Vec_IntSize(p->vLits); i++ )
+        printf( "%d ", p->vLits->pArray[i] );
+    printf( "\n" );
+*/
+    return Counter;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts AIG into the SAT solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_ClausInductiveClauses( Clu_Man_t * p )
+{
+    int nBTLimit = 0;
+    int * pStart, nLitsTot, RetValue, Beg, End, Counter, i, k, f;
+
+    // reset the solver
+    if ( p->pSatMain )  sat_solver_delete( p->pSatMain );
+    p->pSatMain = Cnf_DataWriteIntoSolver( p->pCnf, p->nFrames+1, 0 );
+    if ( p->pSatMain == NULL )
+    {
+        printf( "Error: Main solver is unsat.\n" );
+        return -1;
+    }
+/*
+    // check if the property holds
+    if ( Fra_ClausRunSat0( p ) )
+        printf( "Property holds without strengthening.\n" );
+    else
+        printf( "Property does not hold without strengthening.\n" );
+*/
+    // add the clauses
+    nLitsTot = 2 * p->pCnf->nVars;
+    for ( f = 0; f < p->nFrames; f++ )
+    {
+        Beg = 0;
+        Vec_IntForEachEntry( p->vClauses, End, i )
+        {
+            if ( Vec_IntEntry( p->vCosts, i ) == -1 )
+            {
+                Beg = End;
+                continue;
+            }
+            assert( Vec_IntEntry( p->vCosts, i ) > 0 );
+            assert( End - Beg < 5 );
+            pStart = Vec_IntArray(p->vLits);
+            // add the clause to all timeframes
+            RetValue = sat_solver_addclause( p->pSatMain, pStart + Beg, pStart + End );
+            if ( RetValue == 0 )
+            {
+                printf( "Error: Solver is UNSAT after adding assumption clauses.\n" );
+                return -1;
+            }
+            Beg = End;
+        }
+        // increment literals
+        for ( i = 0; i < Vec_IntSize(p->vLits); i++ )
+            p->vLits->pArray[i] += nLitsTot;
+    }
+
+    // simplify the solver
+    if ( p->pSatMain->qtail != p->pSatMain->qhead )
+    {
+        RetValue = sat_solver_simplify(p->pSatMain);
+        assert( RetValue != 0 );
+        assert( p->pSatMain->qtail == p->pSatMain->qhead );
+    }
+  
+    // check if the property holds
+    if ( Fra_ClausRunSat0( p ) )
+    {
+//        printf( "Property holds with strengthening.\n" );
+        printf( " Property holds.  " );
+    }
+    else
+    {
+        printf( " Property fails.  " );
+        return -2;
+    }
+
+/*
+    // add the property for the first K frames
+    for ( i = 0; i < p->nFrames; i++ )
+    {
+        Aig_Obj_t * pObj;
+        int Lits[2];
+        // set the output literals
+        pObj = Aig_ManPo(p->pAig, 0);
+        Lits[0] = i * nLitsTot + toLitCond( p->pCnf->pVarNums[pObj->Id], 1 ); 
+        // add the clause
+        RetValue = sat_solver_addclause( p->pSatMain, Lits, Lits + 1 );
+//        assert( RetValue == 1 );
+        if ( RetValue == 0 )
+        {
+            printf( "Error: Solver is UNSAT after adding property for the first K frames.\n" );
+            return -1;
+        }
+    }
+*/
+
+    // simplify the solver
+    if ( p->pSatMain->qtail != p->pSatMain->qhead )
+    {
+        RetValue = sat_solver_simplify(p->pSatMain);
+        assert( RetValue != 0 );
+        assert( p->pSatMain->qtail == p->pSatMain->qhead );
+    }
+
+
+    // check the clause in the last timeframe
+    Beg = 0;
+    Counter = 0;
+    Vec_IntForEachEntry( p->vClauses, End, i )
+    {
+        if ( Vec_IntEntry( p->vCosts, i ) == -1 )
+        {
+            Beg = End;
+            continue;
+        }
+        assert( Vec_IntEntry( p->vCosts, i ) > 0 );
+        assert( End - Beg < 5 );
+        pStart = Vec_IntArray(p->vLits);
+
+        for ( k = Beg; k < End; k++ )
+            pStart[k] = lit_neg( pStart[k] );
+        RetValue = sat_solver_solve( p->pSatMain, pStart + Beg, pStart + End, (sint64)nBTLimit, (sint64)0, (sint64)0, (sint64)0 );
+        for ( k = Beg; k < End; k++ )
+            pStart[k] = lit_neg( pStart[k] );
+
+        // the problem is not solved
+        if ( RetValue != l_False )
+        {
+            Beg = End;
+            Vec_IntWriteEntry( p->vCosts, i, -1 );
+            Counter++;
+            continue;
+        }
+        // add the clause
+        RetValue = sat_solver_addclause( p->pSatMain, pStart + Beg, pStart + End );
+//        assert( RetValue == 1 );
+        if ( RetValue == 0 )
+        {
+            printf( "Error: Solver is UNSAT after adding BMC clauses.\n" );
+            return -1;
+        }
+        Beg = End;
+
+        // simplify the solver
+        if ( p->pSatMain->qtail != p->pSatMain->qhead )
+        {
+            RetValue = sat_solver_simplify(p->pSatMain);
+            assert( RetValue != 0 );
+            assert( p->pSatMain->qtail == p->pSatMain->qhead );
+        }
+    }
+
+    // return clauses back to normal
+    nLitsTot = p->nFrames * nLitsTot;
+    for ( i = 0; i < Vec_IntSize(p->vLits); i++ )
+        p->vLits->pArray[i] -= nLitsTot;
+
+    return Counter;
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Converts AIG into the SAT solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Clu_Man_t * Fra_ClausAlloc( Aig_Man_t * pAig, int nFrames, int nClausesMax, int fVerbose, int fVeryVerbose )
+{
+    Clu_Man_t * p;
+    p = ALLOC( Clu_Man_t, 1 );
+    memset( p, 0, sizeof(Clu_Man_t) );
+    p->pAig         = pAig;
+    p->nFrames      = nFrames;
+    p->nClausesMax  = nClausesMax;
+    p->fVerbose     = fVerbose;
+    p->fVeryVerbose = fVeryVerbose;
+    p->nSimWords    = 256;//1024;//64;
+    p->nSimFrames   = 16;//8;//32;
+    p->vValues      = Vec_IntStart( Aig_ManObjNumMax(p->pAig) );
+
+    p->vLits        = Vec_IntAlloc( 1<<14 );
+    p->vClauses     = Vec_IntAlloc( 1<<12 );
+    p->vCosts       = Vec_IntAlloc( 1<<12 );
+
+    p->nCexesAlloc  = 1024;
+    p->vCexes       = Vec_PtrAllocSimInfo( Aig_ManObjNumMax(p->pAig), p->nCexesAlloc/32 );
+    Vec_PtrCleanSimInfo( p->vCexes, 0, p->nCexesAlloc/32 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts AIG into the SAT solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Fra_ClausFree( Clu_Man_t * p )
+{
+    if ( p->vCexes )    Vec_PtrFree( p->vCexes );
+    if ( p->vLits )     Vec_IntFree( p->vLits );
+    if ( p->vClauses )  Vec_IntFree( p->vClauses );
+    if ( p->vCosts )    Vec_IntFree( p->vCosts );
+    if ( p->vValues )   Vec_IntFree( p->vValues );
+    if ( p->pCnf )      Cnf_DataFree( p->pCnf );
+    if ( p->pSatMain )  sat_solver_delete( p->pSatMain );
+    if ( p->pSatBmc )   sat_solver_delete( p->pSatBmc );
+    free( p );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Converts AIG into the SAT solver.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Fra_Claus( Aig_Man_t * pAig, int nFrames, int nClausesMax, int fBmc, int fVerbose, int fVeryVerbose )
+{
+    Clu_Man_t * p;
+    int clk, clkTotal = clock();
+    int Iter, Counter;
+
+    assert( Aig_ManPoNum(pAig) - Aig_ManRegNum(pAig) == 1 );
+
+    // create the manager
+    p = Fra_ClausAlloc( pAig, nFrames, nClausesMax, fVerbose, fVeryVerbose );
+
+clk = clock();
+    // derive CNF
+    p->pAig->nRegs++;
+    p->pCnf = Cnf_DeriveSimple( p->pAig, Aig_ManPoNum(p->pAig) );
+    p->pAig->nRegs--;
+PRT( "CNF    ", clock() - clk );
+
+    // check BMC
+clk = clock();
+    p->pSatBmc = Cnf_DataWriteIntoSolver( p->pCnf, p->nFrames, 1 );
+    if ( p->pSatBmc == NULL )
+    {
+        printf( "Error: BMC solver is unsat.\n" );
+        Fra_ClausFree( p );
+        return 1;
+    }
+    if ( !Fra_ClausRunBmc( p ) )
+    {
+        printf( "Problem trivially fails the base case.\n" );
+        Fra_ClausFree( p );
+        return 1;
+    }
+PRT( "SAT try", clock() - clk );
+
+    // start the SAT solver
+clk = clock();
+    p->pSatMain = Cnf_DataWriteIntoSolver( p->pCnf, p->nFrames+1, 0 );
+    if ( p->pSatMain == NULL )
+    {
+        printf( "Error: Main solver is unsat.\n" );
+        Fra_ClausFree( p );
+        return 1;
+    } 
+    // try solving without additional clauses
+    if ( Fra_ClausRunSat( p ) )
+    {
+        printf( "Problem is inductive without strengthening.\n" );
+        Fra_ClausFree( p );
+        return 1;
+    }
+PRT( "SAT try", clock() - clk );
+ 
+    // collect the candidate inductive clauses using 4-cuts
+clk = clock();
+    Fra_ClausProcessClauses( p );
+    p->nClauses = Vec_IntSize( p->vClauses );
+PRT( "Clauses", clock() - clk );
+
+
+    // check clauses using BMC
+    if ( fBmc ) 
+    {
+clk = clock();
+        Counter = Fra_ClausBmcClauses( p );
+        p->nClauses -= Counter;
+        printf( "BMC disproved %d clauses.\n", Counter );
+PRT( "Cla-bmc", clock() - clk );
+    }
+
+
+    // prove clauses inductively
+clk = clock();
+    Counter = 1;
+    for ( Iter = 0; Counter > 0; Iter++ )
+    {
+        printf( "Iter %3d :  Begin = %5d. ", Iter, p->nClauses );
+        Counter = Fra_ClausInductiveClauses( p );
+        if ( Counter > 0 )
+           p->nClauses -= Counter;
+        printf( "End = %5d. ", p->nClauses );
+//        printf( "\n" );
+        PRT( "Time", clock() - clk );
+        clk = clock();
+    }
+    if ( Counter == -1 )
+        printf( "Fra_Claus(): Internal error.\n" );
+    else if ( Counter == -2 )
+        printf( "Property FAILS after %d iterations of refinement.\n", Iter );
+    else
+        printf( "Property HOLDS inductively after strengthening.\n" );
+
+/*
+clk = clock();
+    if ( Fra_ClausRunSat( p ) )
+        printf( "Problem is solved.\n" );
+    else
+        printf( "Problem is unsolved.\n" );
+PRT( "SAT try", clock() - clk );
+*/
+
+PRT( "TOTAL  ", clock() - clkTotal );
+printf( "\n" );
+    // clean the manager
+    Fra_ClausFree( p );
+    return 1;
+}
+
+////////////////////////////////////////////////////////////////////////
+///                       END OF FILE                                ///
+////////////////////////////////////////////////////////////////////////
+
+