satInterB.c

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
 
#include "satStore.h"
#include "aig/aig/aig.h"
 
ABC_NAMESPACE_IMPL_START
 

 
// variable assignments 
static const lit    LIT_UNDEF = 0xffffffff;
 
// interpolation manager
struct Intb_Man_t_
{
    // clauses of the problems
    Sto_Man_t *     pCnf;         // the set of CNF clauses for A and B
    Vec_Int_t *     vVarsAB;      // the array of global variables
    // various parameters
    int             fVerbose;     // verbosiness flag
    int             fProofVerif;  // verifies the proof
    int             fProofWrite;  // writes the proof file
    int             nVarsAlloc;   // the allocated size of var arrays
    int             nClosAlloc;   // the allocated size of clause arrays
    // internal BCP
    int             nRootSize;    // the number of root level assignments
    int             nTrailSize;   // the number of assignments made 
    lit *           pTrail;       // chronological order of assignments (size nVars)
    lit *           pAssigns;     // assignments by variable (size nVars) 
    char *          pSeens;       // temporary mark (size nVars)
    Sto_Cls_t **    pReasons;     // reasons for each assignment (size nVars)          
    Sto_Cls_t **    pWatches;     // watched clauses for each literal (size 2*nVars)          
    // interpolation data
    Aig_Man_t *     pAig;         // the AIG manager for recording the interpolant
    int *           pVarTypes;    // variable type (size nVars) [1=A, 0=B, <0=AB]
    Aig_Obj_t **    pInters;      // storage for interpolants as truth tables (size nClauses)
    int             nIntersAlloc; // the allocated size of truth table array
    // proof recording
    int             Counter;      // counter of resolved clauses
    int *           pProofNums;   // the proof numbers for each clause (size nClauses)
    FILE *          pFile;        // the file for proof recording
    // internal verification
    lit *           pResLits;     // the literals of the resolvent   
    int             nResLits;     // the number of literals of the resolvent
    int             nResLitsAlloc;// the number of literals of the resolvent
    // runtime stats
    abctime         timeBcp;      // the runtime for BCP
    abctime         timeTrace;    // the runtime of trace construction
    abctime         timeTotal;    // the total runtime of interpolation
};
 
// procedure to get hold of the clauses' truth table 
static inline Aig_Obj_t ** Intb_ManAigRead( Intb_Man_t * pMan, Sto_Cls_t * pCls )                   { return pMan->pInters + pCls->Id;          }
static inline void         Intb_ManAigClear( Intb_Man_t * pMan, Aig_Obj_t ** p )                    { *p = Aig_ManConst0(pMan->pAig);           }
static inline void         Intb_ManAigFill( Intb_Man_t * pMan, Aig_Obj_t ** p )                     { *p = Aig_ManConst1(pMan->pAig);           }
static inline void         Intb_ManAigCopy( Intb_Man_t * pMan, Aig_Obj_t ** p, Aig_Obj_t ** q )     { *p = *q;                                  }
static inline void         Intb_ManAigAnd( Intb_Man_t * pMan, Aig_Obj_t ** p, Aig_Obj_t ** q )      { *p = Aig_And(pMan->pAig, *p, *q);         }
static inline void         Intb_ManAigOr( Intb_Man_t * pMan, Aig_Obj_t ** p, Aig_Obj_t ** q )       { *p = Aig_Or(pMan->pAig, *p, *q);          }
static inline void         Intb_ManAigOrNot( Intb_Man_t * pMan, Aig_Obj_t ** p, Aig_Obj_t ** q )    { *p = Aig_Or(pMan->pAig, *p, Aig_Not(*q)); }
static inline void         Intb_ManAigOrVar( Intb_Man_t * pMan, Aig_Obj_t ** p, int v )             { *p = Aig_Or(pMan->pAig, *p, Aig_IthVar(pMan->pAig, v));          }
static inline void         Intb_ManAigOrNotVar( Intb_Man_t * pMan, Aig_Obj_t ** p, int v )          { *p = Aig_Or(pMan->pAig, *p, Aig_Not(Aig_IthVar(pMan->pAig, v))); }
static inline void         Intb_ManAigMux0( Intb_Man_t * pMan, Aig_Obj_t ** p, Aig_Obj_t ** q, int v){ *p = Aig_Mux(pMan->pAig, Aig_IthVar(pMan->pAig, v), *q, *p);     }
static inline void         Intb_ManAigMux1( Intb_Man_t * pMan, Aig_Obj_t ** p, Aig_Obj_t ** q, int v){ *p = Aig_Mux(pMan->pAig, Aig_IthVar(pMan->pAig, v), *p, *q);     }
 
// reading/writing the proof for a clause
static inline int          Intb_ManProofGet( Intb_Man_t * p, Sto_Cls_t * pCls )                  { return p->pProofNums[pCls->Id];           }
static inline void         Intb_ManProofSet( Intb_Man_t * p, Sto_Cls_t * pCls, int n )           { p->pProofNums[pCls->Id] = n;              }


Intb_Man_t * Intb_ManAlloc()
{
    Intb_Man_t * p;
    // allocate the manager
    p = (Intb_Man_t *)ABC_ALLOC( char, sizeof(Intb_Man_t) );
    memset( p, 0, sizeof(Intb_Man_t) );
    // verification
    p->nResLitsAlloc = (1<<16);
    p->pResLits = ABC_ALLOC( lit, p->nResLitsAlloc );
    // parameters
    p->fProofWrite = 0;
    p->fProofVerif = 1;
    return p;    
}

int Intb_ManGlobalVars( Intb_Man_t * p )
{
    Sto_Cls_t * pClause;
    int LargeNum = -100000000;
    int Var, nVarsAB, v;
 
    // mark the variable encountered in the clauses of A
    Sto_ManForEachClauseRoot( p->pCnf, pClause )
    {
        if ( !pClause->fA )
            break;
        for ( v = 0; v < (int)pClause->nLits; v++ )
            p->pVarTypes[lit_var(pClause->pLits[v])] = 1;
    }
 
    // check variables that appear in clauses of B
    nVarsAB = 0;
    Sto_ManForEachClauseRoot( p->pCnf, pClause )
    {
        if ( pClause->fA )
            continue;
        for ( v = 0; v < (int)pClause->nLits; v++ )
        {
            Var = lit_var(pClause->pLits[v]);
            if ( p->pVarTypes[Var] == 1 ) // var of A
            {
                // change it into a global variable
                nVarsAB++;
                p->pVarTypes[Var] = LargeNum;
            }
        }
    }
    assert( nVarsAB <= Vec_IntSize(p->vVarsAB) );
 
    // order global variables
    nVarsAB = 0;
    Vec_IntForEachEntry( p->vVarsAB, Var, v )
        p->pVarTypes[Var] = -(1+nVarsAB++);
 
    // check that there is no extra global variables
    for ( v = 0; v < p->pCnf->nVars; v++ )
        assert( p->pVarTypes[v] != LargeNum );
    return nVarsAB;
}

void Intb_ManResize( Intb_Man_t * p )
{
    p->Counter = 0;
    // check if resizing is needed
    if ( p->nVarsAlloc < p->pCnf->nVars )
    {
        // find the new size
        if ( p->nVarsAlloc == 0 )
            p->nVarsAlloc = 1;
        while ( p->nVarsAlloc < p->pCnf->nVars ) 
            p->nVarsAlloc *= 2;
        // resize the arrays
        p->pTrail    = ABC_REALLOC(lit,         p->pTrail,    p->nVarsAlloc );
        p->pAssigns  = ABC_REALLOC(lit,         p->pAssigns,  p->nVarsAlloc );
        p->pSeens    = ABC_REALLOC(char,        p->pSeens,    p->nVarsAlloc );
        p->pVarTypes = ABC_REALLOC(int,         p->pVarTypes, p->nVarsAlloc );
        p->pReasons  = ABC_REALLOC(Sto_Cls_t *, p->pReasons,  p->nVarsAlloc );
        p->pWatches  = ABC_REALLOC(Sto_Cls_t *, p->pWatches,  p->nVarsAlloc*2 );
    }
 
    // clean the free space
    memset( p->pAssigns , 0xff, sizeof(lit) * p->pCnf->nVars );
    memset( p->pSeens   , 0,    sizeof(char) * p->pCnf->nVars );
    memset( p->pVarTypes, 0,    sizeof(int) * p->pCnf->nVars );
    memset( p->pReasons , 0,    sizeof(Sto_Cls_t *) * p->pCnf->nVars );
    memset( p->pWatches , 0,    sizeof(Sto_Cls_t *) * p->pCnf->nVars*2 );
 
    // compute the number of common variables
    Intb_ManGlobalVars( p );
 
    // check if resizing of clauses is needed
    if ( p->nClosAlloc < p->pCnf->nClauses )
    {
        // find the new size
        if ( p->nClosAlloc == 0 )
            p->nClosAlloc = 1;
        while ( p->nClosAlloc < p->pCnf->nClauses ) 
            p->nClosAlloc *= 2;
        // resize the arrays
        p->pProofNums = ABC_REALLOC( int, p->pProofNums,  p->nClosAlloc );
    }
    memset( p->pProofNums, 0, sizeof(int) * p->pCnf->nClauses );
 
    // check if resizing of truth tables is needed
    if ( p->nIntersAlloc < p->pCnf->nClauses )
    {
        p->nIntersAlloc = p->pCnf->nClauses;
        p->pInters = ABC_REALLOC( Aig_Obj_t *, p->pInters, p->nIntersAlloc );
    }
    memset( p->pInters, 0, sizeof(Aig_Obj_t *) * p->pCnf->nClauses );
}

void Intb_ManFree( Intb_Man_t * p )
{
/*
    printf( "Runtime stats:\n" );
ABC_PRT( "BCP     ", p->timeBcp   );
ABC_PRT( "Trace   ", p->timeTrace );
ABC_PRT( "TOTAL   ", p->timeTotal );
*/
    ABC_FREE( p->pInters );
    ABC_FREE( p->pProofNums );
    ABC_FREE( p->pTrail );
    ABC_FREE( p->pAssigns );
    ABC_FREE( p->pSeens );
    ABC_FREE( p->pVarTypes );
    ABC_FREE( p->pReasons );
    ABC_FREE( p->pWatches );
    ABC_FREE( p->pResLits );
    ABC_FREE( p );
}
 
 
 

void Intb_ManPrintClause( Intb_Man_t * p, Sto_Cls_t * pClause )
{
    int i;
    printf( "Clause ID = %d. Proof = %d. {", pClause->Id, Intb_ManProofGet(p, pClause) );
    for ( i = 0; i < (int)pClause->nLits; i++ )
        printf( " %d", pClause->pLits[i] );
    printf( " }\n" );
}

void Intb_ManPrintResolvent( lit * pResLits, int nResLits )
{
    int i;
    printf( "Resolvent: {" );
    for ( i = 0; i < nResLits; i++ )
        printf( " %d", pResLits[i] );
    printf( " }\n" );
}

void Intb_ManPrintInterOne( Intb_Man_t * p, Sto_Cls_t * pClause )
{
    printf( "Clause %2d :  ", pClause->Id );
//    Extra_PrintBinary___( stdout, Intb_ManAigRead(p, pClause), (1 << p->nVarsAB) );
    printf( "\n" );
}
 
 

static inline void Intb_ManWatchClause( Intb_Man_t * p, Sto_Cls_t * pClause, lit Lit )
{
    assert( lit_check(Lit, p->pCnf->nVars) );
    if ( pClause->pLits[0] == Lit )
        pClause->pNext0 = p->pWatches[lit_neg(Lit)];  
    else
    {
        assert( pClause->pLits[1] == Lit );
        pClause->pNext1 = p->pWatches[lit_neg(Lit)];  
    }
    p->pWatches[lit_neg(Lit)] = pClause;
}
 

static inline int Intb_ManEnqueue( Intb_Man_t * p, lit Lit, Sto_Cls_t * pReason )
{
    int Var = lit_var(Lit);
    if ( p->pAssigns[Var] != LIT_UNDEF )
        return p->pAssigns[Var] == Lit;
    p->pAssigns[Var] = Lit;
    p->pReasons[Var] = pReason;
    p->pTrail[p->nTrailSize++] = Lit;
//printf( "assigning var %d value %d\n", Var, !lit_sign(Lit) );
    return 1;
}

static inline void Intb_ManCancelUntil( Intb_Man_t * p, int Level )
{
    lit Lit;
    int i, Var;
    for ( i = p->nTrailSize - 1; i >= Level; i-- )
    {
        Lit = p->pTrail[i];
        Var = lit_var( Lit );
        p->pReasons[Var] = NULL;
        p->pAssigns[Var] = LIT_UNDEF;
//printf( "cancelling var %d\n", Var );
    }
    p->nTrailSize = Level;
}

static inline Sto_Cls_t * Intb_ManPropagateOne( Intb_Man_t * p, lit Lit )
{
    Sto_Cls_t ** ppPrev, * pCur, * pTemp;
    lit LitF = lit_neg(Lit);
    int i;
    // iterate through the literals
    ppPrev = p->pWatches + Lit;
    for ( pCur = p->pWatches[Lit]; pCur; pCur = *ppPrev )
    {
        // make sure the false literal is in the second literal of the clause
        if ( pCur->pLits[0] == LitF )
        {
            pCur->pLits[0] = pCur->pLits[1];
            pCur->pLits[1] = LitF;
            pTemp = pCur->pNext0;
            pCur->pNext0 = pCur->pNext1;
            pCur->pNext1 = pTemp;
        }
        assert( pCur->pLits[1] == LitF );
 
        // if the first literal is true, the clause is satisfied
        if ( pCur->pLits[0] == p->pAssigns[lit_var(pCur->pLits[0])] )
        {
            ppPrev = &pCur->pNext1;
            continue;
        }
 
        // look for a new literal to watch
        for ( i = 2; i < (int)pCur->nLits; i++ )
        {
            // skip the case when the literal is false
            if ( lit_neg(pCur->pLits[i]) == p->pAssigns[lit_var(pCur->pLits[i])] )
                continue;
            // the literal is either true or unassigned - watch it
            pCur->pLits[1] = pCur->pLits[i];
            pCur->pLits[i] = LitF;
            // remove this clause from the watch list of Lit
            *ppPrev = pCur->pNext1;
            // add this clause to the watch list of pCur->pLits[i] (now it is pCur->pLits[1])
            Intb_ManWatchClause( p, pCur, pCur->pLits[1] );
            break;
        }
        if ( i < (int)pCur->nLits ) // found new watch
            continue;
 
        // clause is unit - enqueue new implication
        if ( Intb_ManEnqueue(p, pCur->pLits[0], pCur) )
        {
            ppPrev = &pCur->pNext1;
            continue;
        }
 
        // conflict detected - return the conflict clause
        return pCur;
    }
    return NULL;
}

Sto_Cls_t * Intb_ManPropagate( Intb_Man_t * p, int Start )
{
    Sto_Cls_t * pClause;
    int i;
    abctime clk = Abc_Clock();
    for ( i = Start; i < p->nTrailSize; i++ )
    {
        pClause = Intb_ManPropagateOne( p, p->pTrail[i] );
        if ( pClause )
        {
p->timeBcp += Abc_Clock() - clk;
            return pClause;
        }
    }
p->timeBcp += Abc_Clock() - clk;
    return NULL;
}
 

void Intb_ManProofWriteOne( Intb_Man_t * p, Sto_Cls_t * pClause )
{
    Intb_ManProofSet( p, pClause, ++p->Counter );
 
    if ( p->fProofWrite )
    {
        int v;
        fprintf( p->pFile, "%d", Intb_ManProofGet(p, pClause) );
        for ( v = 0; v < (int)pClause->nLits; v++ )
            fprintf( p->pFile, " %d", lit_print(pClause->pLits[v]) );
        fprintf( p->pFile, " 0 0\n" );
    }
}

int Intb_ManGetGlobalVar( Intb_Man_t * p, int Var )
{
    int VarAB;
    if ( p->pVarTypes[Var] >= 0 ) // global var
        return -1;
    VarAB = -p->pVarTypes[Var]-1;
    assert( VarAB >= 0 && VarAB < Vec_IntSize(p->vVarsAB) );
    return VarAB;
}

int Intb_ManProofTraceOne( Intb_Man_t * p, Sto_Cls_t * pConflict, Sto_Cls_t * pFinal )
{
    Sto_Cls_t * pReason;
    int i, v, Var, PrevId;
    int fPrint = 0;
    abctime clk = Abc_Clock();
 
    // collect resolvent literals
    if ( p->fProofVerif )
    {
        assert( (int)pConflict->nLits <= p->nResLitsAlloc );
        memcpy( p->pResLits, pConflict->pLits, sizeof(lit) * pConflict->nLits );
        p->nResLits = pConflict->nLits;
    }
 
    // mark all the variables in the conflict as seen
    for ( v = 0; v < (int)pConflict->nLits; v++ )
        p->pSeens[lit_var(pConflict->pLits[v])] = 1;
 
    // start the anticedents
//    pFinal->pAntis = Vec_PtrAlloc( 32 );
//    Vec_PtrPush( pFinal->pAntis, pConflict );
 
    if ( p->pCnf->nClausesA )
        Intb_ManAigCopy( p, Intb_ManAigRead(p, pFinal), Intb_ManAigRead(p, pConflict) );
 
    // follow the trail backwards
    PrevId = Intb_ManProofGet(p, pConflict);
    for ( i = p->nTrailSize - 1; i >= 0; i-- )
    {
        // skip literals that are not involved
        Var = lit_var(p->pTrail[i]);
        if ( !p->pSeens[Var] )
            continue;
        p->pSeens[Var] = 0;
 
        // skip literals of the resulting clause
        pReason = p->pReasons[Var];
        if ( pReason == NULL )
            continue;
        assert( p->pTrail[i] == pReason->pLits[0] );
 
        // add the variables to seen
        for ( v = 1; v < (int)pReason->nLits; v++ )
            p->pSeens[lit_var(pReason->pLits[v])] = 1;
 
        // record the reason clause
        assert( Intb_ManProofGet(p, pReason) > 0 );
        p->Counter++;
        if ( p->fProofWrite )
            fprintf( p->pFile, "%d * %d %d 0\n", p->Counter, PrevId, Intb_ManProofGet(p, pReason) );
        PrevId = p->Counter;
 
        if ( p->pCnf->nClausesA )
        {
            if ( p->pVarTypes[Var] == 1 )// || rand() % 10 == 0 ) // var of A
                Intb_ManAigOr( p, Intb_ManAigRead(p, pFinal), Intb_ManAigRead(p, pReason) );
            else if ( p->pVarTypes[Var] == 0 ) // var of B
                Intb_ManAigAnd( p, Intb_ManAigRead(p, pFinal), Intb_ManAigRead(p, pReason) );
            else
            {
                int VarAB = Intb_ManGetGlobalVar(p, Var);
                // check that the var is present in the reason
                for ( v = 0; v < (int)pReason->nLits; v++ )
                    if ( lit_var(pReason->pLits[v]) == Var )
                        break;
                assert( v < (int)pReason->nLits );
                if ( lit_sign(pReason->pLits[v]) ) // negative polarity
                    Intb_ManAigMux0( p, Intb_ManAigRead(p, pFinal), Intb_ManAigRead(p, pReason), VarAB );
                else
                    Intb_ManAigMux1( p, Intb_ManAigRead(p, pFinal), Intb_ManAigRead(p, pReason), VarAB );
            }
        }
 
        // resolve the temporary resolvent with the reason clause
        if ( p->fProofVerif )
        {
            int v1, v2; 
            if ( fPrint )
                Intb_ManPrintResolvent( p->pResLits, p->nResLits );
            // check that the var is present in the resolvent
            for ( v1 = 0; v1 < p->nResLits; v1++ )
                if ( lit_var(p->pResLits[v1]) == Var )
                    break;
            if ( v1 == p->nResLits )
                printf( "Recording clause %d: Cannot find variable %d in the temporary resolvent.\n", pFinal->Id, Var );
            if ( p->pResLits[v1] != lit_neg(pReason->pLits[0]) )
                printf( "Recording clause %d: The resolved variable %d is in the wrong polarity.\n", pFinal->Id, Var );
            // remove this variable from the resolvent
            assert( lit_var(p->pResLits[v1]) == Var );
            p->nResLits--;
            for ( ; v1 < p->nResLits; v1++ )
                p->pResLits[v1] = p->pResLits[v1+1];
            // add variables of the reason clause
            for ( v2 = 1; v2 < (int)pReason->nLits; v2++ )
            {
                for ( v1 = 0; v1 < p->nResLits; v1++ )
                    if ( lit_var(p->pResLits[v1]) == lit_var(pReason->pLits[v2]) )
                        break;
                // if it is a new variable, add it to the resolvent
                if ( v1 == p->nResLits ) 
                {
                    if ( p->nResLits == p->nResLitsAlloc )
                        printf( "Recording clause %d: Ran out of space for intermediate resolvent.\n", pFinal->Id );
                    p->pResLits[ p->nResLits++ ] = pReason->pLits[v2];
                    continue;
                }
                // if the variable is the same, the literal should be the same too
                if ( p->pResLits[v1] == pReason->pLits[v2] )
                    continue;
                // the literal is different
                printf( "Recording clause %d: Trying to resolve the clause with more than one opposite literal.\n", pFinal->Id );
            }
        }
//        Vec_PtrPush( pFinal->pAntis, pReason );
    }
 
    // unmark all seen variables
//    for ( i = p->nTrailSize - 1; i >= 0; i-- )
//        p->pSeens[lit_var(p->pTrail[i])] = 0;
    // check that the literals are unmarked
//    for ( i = p->nTrailSize - 1; i >= 0; i-- )
//        assert( p->pSeens[lit_var(p->pTrail[i])] == 0 );
 
    // use the resulting clause to check the correctness of resolution
    if ( p->fProofVerif )
    {
        int v1, v2; 
        if ( fPrint )
            Intb_ManPrintResolvent( p->pResLits, p->nResLits );
        for ( v1 = 0; v1 < p->nResLits; v1++ )
        {
            for ( v2 = 0; v2 < (int)pFinal->nLits; v2++ )
                if ( pFinal->pLits[v2] == p->pResLits[v1] )
                    break;
            if ( v2 < (int)pFinal->nLits )
                continue;
            break;
        }
        if ( v1 < p->nResLits )
        {
            printf( "Recording clause %d: The final resolvent is wrong.\n", pFinal->Id );
            Intb_ManPrintClause( p, pConflict );
            Intb_ManPrintResolvent( p->pResLits, p->nResLits );
            Intb_ManPrintClause( p, pFinal );
        }
 
        // if there are literals in the clause that are not in the resolvent
        // it means that the derived resolvent is stronger than the clause
        // we can replace the clause with the resolvent by removing these literals
        if ( p->nResLits != (int)pFinal->nLits )
        {
            for ( v1 = 0; v1 < (int)pFinal->nLits; v1++ )
            {
                for ( v2 = 0; v2 < p->nResLits; v2++ )
                    if ( pFinal->pLits[v1] == p->pResLits[v2] )
                        break;
                if ( v2 < p->nResLits )
                    continue;
                // remove literal v1 from the final clause
                pFinal->nLits--;
                for ( v2 = v1; v2 < (int)pFinal->nLits; v2++ )
                    pFinal->pLits[v2] = pFinal->pLits[v2+1];
                v1--;
            }
            assert( p->nResLits == (int)pFinal->nLits );
        }
    }
p->timeTrace += Abc_Clock() - clk;
 
    // return the proof pointer 
    if ( p->pCnf->nClausesA )
    {
//        Intb_ManPrintInterOne( p, pFinal );
    }
    Intb_ManProofSet( p, pFinal, p->Counter );
    // make sure the same proof ID is not asssigned to two consecutive clauses
    assert( p->pProofNums[pFinal->Id-1] != p->Counter );
//    if ( p->pProofNums[pFinal->Id] == p->pProofNums[pFinal->Id-1] )
//        p->pProofNums[pFinal->Id] = p->pProofNums[pConflict->Id];
    return p->Counter;
}

int Intb_ManProofRecordOne( Intb_Man_t * p, Sto_Cls_t * pClause )
{
    Sto_Cls_t * pConflict;
    int i;
 
    // empty clause never ends up there
    assert( pClause->nLits > 0 );
    if ( pClause->nLits == 0 )
        printf( "Error: Empty clause is attempted.\n" );
 
    assert( !pClause->fRoot );
    assert( p->nTrailSize == p->nRootSize );
 
    // if any of the clause literals are already assumed
    // it means that the clause is redundant and can be skipped
    for ( i = 0; i < (int)pClause->nLits; i++ )
        if ( p->pAssigns[lit_var(pClause->pLits[i])] == pClause->pLits[i] )
            return 1;
 
    // add assumptions to the trail
    for ( i = 0; i < (int)pClause->nLits; i++ )
        if ( !Intb_ManEnqueue( p, lit_neg(pClause->pLits[i]), NULL ) )
        {
            assert( 0 ); // impossible
            return 0;
        }
 
    // propagate the assumptions
    pConflict = Intb_ManPropagate( p, p->nRootSize );
    if ( pConflict == NULL )
    {
        assert( 0 ); // cannot prove
        return 0;
    } 
 
    // skip the clause if it is weaker or the same as the conflict clause
    if ( pClause->nLits >= pConflict->nLits )
    {
        // check if every literal of conflict clause can be found in the given clause
        int j;
        for ( i = 0; i < (int)pConflict->nLits; i++ )
        {
            for ( j = 0; j < (int)pClause->nLits; j++ )
                if ( pConflict->pLits[i] == pClause->pLits[j] )
                    break;
            if ( j == (int)pClause->nLits ) // literal pConflict->pLits[i] is not found
                break;
        }
        if ( i == (int)pConflict->nLits ) // all lits are found
        {
            // undo to the root level
            Intb_ManCancelUntil( p, p->nRootSize );
            return 1;
        }
    }
 
    // construct the proof
    Intb_ManProofTraceOne( p, pConflict, pClause );
 
    // undo to the root level
    Intb_ManCancelUntil( p, p->nRootSize );
 
    // add large clauses to the watched lists
    if ( pClause->nLits > 1 )
    {
        Intb_ManWatchClause( p, pClause, pClause->pLits[0] );
        Intb_ManWatchClause( p, pClause, pClause->pLits[1] );
        return 1;
    }
    assert( pClause->nLits == 1 );
 
    // if the clause proved is unit, add it and propagate
    if ( !Intb_ManEnqueue( p, pClause->pLits[0], pClause ) )
    {
        assert( 0 ); // impossible
        return 0;
    }
 
    // propagate the assumption
    pConflict = Intb_ManPropagate( p, p->nRootSize );
    if ( pConflict )
    {
        // construct the proof
        Intb_ManProofTraceOne( p, pConflict, p->pCnf->pEmpty );
//        if ( p->fVerbose )
//            printf( "Found last conflict after adding unit clause number %d!\n", pClause->Id );
        return 0;
    }
 
    // update the root level
    p->nRootSize = p->nTrailSize;
    return 1;
}

int Intb_ManProcessRoots( Intb_Man_t * p )
{
    Sto_Cls_t * pClause;
    int Counter;
 
    // make sure the root clauses are preceeding the learnt clauses
    Counter = 0;
    Sto_ManForEachClause( p->pCnf, pClause )
    {
        assert( (int)pClause->fA    == (Counter < (int)p->pCnf->nClausesA) );
        assert( (int)pClause->fRoot == (Counter < (int)p->pCnf->nRoots)    );
        Counter++;
    }
    assert( p->pCnf->nClauses == Counter );
 
    // make sure the last clause if empty
    assert( p->pCnf->pTail->nLits == 0 );
 
    // go through the root unit clauses
    p->nTrailSize = 0;
    Sto_ManForEachClauseRoot( p->pCnf, pClause )
    {
        // create watcher lists for the root clauses
        if ( pClause->nLits > 1 )
        {
            Intb_ManWatchClause( p, pClause, pClause->pLits[0] );
            Intb_ManWatchClause( p, pClause, pClause->pLits[1] );
        }
        // empty clause and large clauses
        if ( pClause->nLits != 1 )
            continue;
        // unit clause
        assert( lit_check(pClause->pLits[0], p->pCnf->nVars) );
        if ( !Intb_ManEnqueue( p, pClause->pLits[0], pClause ) )
        {
            // detected root level conflict
//            printf( "Error in Intb_ManProcessRoots(): Detected a root-level conflict too early!\n" );
//            assert( 0 );
            // detected root level conflict
            Intb_ManProofTraceOne( p, pClause, p->pCnf->pEmpty );
            if ( p->fVerbose )
                printf( "Found root level conflict!\n" );
            return 0;
        }
    }
 
    // propagate the root unit clauses
    pClause = Intb_ManPropagate( p, 0 );
    if ( pClause )
    {
        // detected root level conflict
        Intb_ManProofTraceOne( p, pClause, p->pCnf->pEmpty );
        if ( p->fVerbose )
            printf( "Found root level conflict!\n" );
        return 0;
    }
 
    // set the root level
    p->nRootSize = p->nTrailSize;
    return 1;
}

void Intb_ManPrepareInter( Intb_Man_t * p )
{
    Sto_Cls_t * pClause;
    int Var, VarAB, v;
 
    // set interpolants for root clauses
    Sto_ManForEachClauseRoot( p->pCnf, pClause )
    {
        if ( !pClause->fA ) // clause of B
        {
            Intb_ManAigFill( p, Intb_ManAigRead(p, pClause) );
//            Intb_ManPrintInterOne( p, pClause );
            continue;
        }
        // clause of A
        Intb_ManAigClear( p, Intb_ManAigRead(p, pClause) );
        for ( v = 0; v < (int)pClause->nLits; v++ )
        {
            Var = lit_var(pClause->pLits[v]);
            if ( p->pVarTypes[Var] < 0 ) // global var
            {
                VarAB = -p->pVarTypes[Var]-1;
                assert( VarAB >= 0 && VarAB < Vec_IntSize(p->vVarsAB) );
                if ( lit_sign(pClause->pLits[v]) ) // negative var
                    Intb_ManAigOrNotVar( p, Intb_ManAigRead(p, pClause), VarAB );
                else
                    Intb_ManAigOrVar( p, Intb_ManAigRead(p, pClause), VarAB );
            }
        }
//        Intb_ManPrintInterOne( p, pClause );
    }
}

void * Intb_ManInterpolate( Intb_Man_t * p, Sto_Man_t * pCnf, void * vVarsAB, int fVerbose )
{
    Aig_Man_t * pRes;
    Aig_Obj_t * pObj;
    Sto_Cls_t * pClause;
    int RetValue = 1;
    abctime clkTotal = Abc_Clock();
 
    // check that the CNF makes sense
    assert( pCnf->nVars > 0 && pCnf->nClauses > 0 );
    p->pCnf = pCnf;
    p->fVerbose = fVerbose;
    p->vVarsAB = (Vec_Int_t *)vVarsAB;
    p->pAig = pRes = Aig_ManStart( 10000 );
    Aig_IthVar( p->pAig, Vec_IntSize(p->vVarsAB) - 1 );
 
    // adjust the manager
    Intb_ManResize( p );
 
    // prepare the interpolant computation
    Intb_ManPrepareInter( p );
 
    // construct proof for each clause
    // start the proof
    if ( p->fProofWrite )
    {
        p->pFile = fopen( "proof.cnf_", "w" );
        p->Counter = 0;
    }
 
    // write the root clauses
    Sto_ManForEachClauseRoot( p->pCnf, pClause )
        Intb_ManProofWriteOne( p, pClause );
 
    // propagate root level assignments
    if ( Intb_ManProcessRoots( p ) )
    {
        // if there is no conflict, consider learned clauses
        Sto_ManForEachClause( p->pCnf, pClause )
        {
            if ( pClause->fRoot )
                continue;
            if ( !Intb_ManProofRecordOne( p, pClause ) )
            {
                RetValue = 0;
                break;
            }
        }
    }
 
    // stop the proof
    if ( p->fProofWrite )
    { 
        fclose( p->pFile );
//        Sat_ProofChecker( "proof.cnf_" );
        p->pFile = NULL;    
    }
 
    if ( fVerbose )
    {
//        ABC_PRT( "Interpo", Abc_Clock() - clkTotal );
    printf( "Vars = %d. Roots = %d. Learned = %d. Resol steps = %d.  Ave = %.2f.  Mem = %.2f MB\n", 
        p->pCnf->nVars, p->pCnf->nRoots, p->pCnf->nClauses-p->pCnf->nRoots, p->Counter,  
        1.0*(p->Counter-p->pCnf->nRoots)/(p->pCnf->nClauses-p->pCnf->nRoots), 
        1.0*Sto_ManMemoryReport(p->pCnf)/(1<<20) );
p->timeTotal += Abc_Clock() - clkTotal;
    }
 
    pObj = *Intb_ManAigRead( p, p->pCnf->pTail );
    Aig_ObjCreateCo( pRes, pObj );
    Aig_ManCleanup( pRes );
 
    p->pAig = NULL;
    return pRes;
    
}
 

Aig_Man_t * Intb_ManDeriveClauses( Intb_Man_t * pMan, Sto_Man_t * pCnf, int fClausesA )
{
    Aig_Man_t * p;
    Aig_Obj_t * pMiter, * pSum, * pLit;
    Sto_Cls_t * pClause;
    int Var, VarAB, v;
    p = Aig_ManStart( 10000 );
    pMiter = Aig_ManConst1(p);
    Sto_ManForEachClauseRoot( pCnf, pClause )
    {
        if ( fClausesA ^ pClause->fA ) // clause of B
            continue;
        // clause of A
        pSum = Aig_ManConst0(p);
        for ( v = 0; v < (int)pClause->nLits; v++ )
        {
            Var = lit_var(pClause->pLits[v]);
            if ( pMan->pVarTypes[Var] < 0 ) // global var
            {
                VarAB = -pMan->pVarTypes[Var]-1;
                assert( VarAB >= 0 && VarAB < Vec_IntSize(pMan->vVarsAB) );
                pLit = Aig_NotCond( Aig_IthVar(p, VarAB), lit_sign(pClause->pLits[v]) );
            }
            else
                pLit = Aig_NotCond( Aig_IthVar(p, Vec_IntSize(pMan->vVarsAB)+1+Var), lit_sign(pClause->pLits[v]) );
            pSum = Aig_Or( p, pSum, pLit );
        }
        pMiter = Aig_And( p, pMiter, pSum );
    }
    Aig_ObjCreateCo( p, pMiter );
    return p;
}

 
 
ABC_NAMESPACE_IMPL_END