private void LookForUnitRefutation(OTTERAnswerHandler ansHandler,
IndexedClauses idxdClauses, Clause clause, ISet<Clause> sos,
ISet<Clause> usable)
{
ISet<Clause> toCheck = new HashedSet<Clause>();
if (ansHandler.IsCheckForUnitRefutation(clause))
{
foreach (Clause s in sos)
{
if (s.IsUnitClause())
{
toCheck.Add(s);
}
}
foreach (Clause u in usable)
{
if (u.IsUnitClause())
{
toCheck.Add(u);
}
}
}
if (toCheck.Count > 0)
{
toCheck = this.Infer(clause, toCheck);
foreach (Clause t in toCheck)
{
// * clause <- SIMPLIFY(clause)
var simplifiedT = ClauseSimplifier.Simplify(t);
// * discard clause if it is a tautology
if (simplifiedT.IsTautology())
{
continue;
}
// * if clause has no literals then a refutation has been found
// or if it just Contains the answer literal.
if (!ansHandler.IsAnswer(simplifiedT))
{
// * sos <- [clause | sos]
// This check ensure duplicate clauses are not
// introduced which will cause the
// ILightestClauseHeuristic to loop continuously
// on the same pair of objects.
if (!sos.Contains(simplifiedT) && !usable.Contains(simplifiedT))
{
idxdClauses.addClause(simplifiedT, sos, usable);
}
}
if (ansHandler.IsComplete())
{
break;
}
}
}
}