Exemple #1
0
bool SimpSMTSolver::asymm(Var v, Clause& c)
{
  assert(decisionLevel() == 0);

  if (c.mark() || satisfied(c)) return true;

  trail_lim.push(trail.size());
  Lit l = lit_Undef;
  for (int i = 0; i < c.size(); i++)
    if (var(c[i]) != v && value(c[i]) != l_False)
    {
      uncheckedEnqueue(~c[i]);
    }
    else
      l = c[i];

  if (propagate() != NULL){
    cancelUntil(0);
    asymm_lits++;
    if (!strengthenClause(c, l))
      return false;
  }else
    cancelUntil(0);

  return true;
}
void SimpSolver::removeClause(Clause& c)
{
    assert(!c.learnt());

    if (use_simplification)
        for (int i = 0; i < c.size(); i++){
            n_occ[toInt(c[i])]--;
            updateElimHeap(var(c[i]));
        }

    detachClause(c);
    c.mark(1);
}
bool SimpSolver::strengthenClause(Clause& c, Lit l)
{
    assert(decisionLevel() == 0);
    assert(c.mark() == 0);
    assert(!c.learnt());
    assert(find(watches[toInt(~c[0])], &c));
    assert(find(watches[toInt(~c[1])], &c));

    // FIX: this is too inefficient but would be nice to have (properly implemented)
    // if (!find(subsumption_queue, &c))
    subsumption_queue.insert(&c);

    // If l is watched, delete it from watcher list and watch a new literal
    if (c[0] == l || c[1] == l){
        Lit other = c[0] == l ? c[1] : c[0];
        if (c.size() == 2){
            removeClause(c);
            c.strengthen(l);
        }else{
            c.strengthen(l);
            remove(watches[toInt(~l)], &c);

            // Add a watch for the correct literal
            watches[toInt(~(c[1] == other ? c[0] : c[1]))].push(&c);

            // !! this version assumes that remove does not change the order !!
            //watches[toInt(~c[1])].push(&c);
            clauses_literals -= 1;
        }
    }
    else{
        c.strengthen(l);
        clauses_literals -= 1;
    }

    // if subsumption-indexing is active perform the necessary updates
    if (use_simplification){
        remove(occurs[var(l)], &c);
        n_occ[toInt(l)]--;
        updateElimHeap(var(l));
    }

    return c.size() == 1 ? enqueue(c[0]) && propagate() == NULL : true;
}