result_type operator() (logic::tag::nand_tag const& tag, result_type lhs, result_type rhs )
{
result_type out = { int(impl::new_var_id()) };
clause3(-lhs,-rhs,-out);
clause2( rhs, out);
clause2( lhs, out);
return out;
}
int
subsumes(const Clause &cl1, const Clause &cl2, Substitutions &s)
{
// clear substitution list
s.clear();
// make sure the clauses are not the same one.
// this check works since the index in literals
// are never reassigned.
//
if (cl1 == cl2)
{
return(NOMATCH);
}
// check that every class in clause 1 exists in clause 2.
if (subset(cl1, cl2) != OK)
{
return(NOMATCH);
}
// now start the actual subsumption algorithm.
Substitutions subs;
Clause clause2(cl2);
if (groundSubstitutions(clause2, subs) != OK)
{
ERROR("groundSubstitutions failed.", errno);
return(NOTOK);
}
// convert second clause to a ground clause
if (subs.applyTo(clause2) != OK)
{
ERROR("applyTo failed.", errno);
return(NOTOK);
}
// copy clauses to arrays
Array<Literal> clarray1(1, cl1.getTotalMembers());
ClauseIterator cl1Iter(cl1);
for (int i=1; !cl1Iter.done(); i++, cl1Iter++)
{
clarray1[i] = cl1Iter();
}
Array<Literal> clarray2(1, cl2.getTotalMembers());
ClauseIterator cl2Iter(clause2);
#ifdef SC42
for (i=1; !cl2Iter.done(); i++, cl2Iter++)
#else
for (int i=1; !cl2Iter.done(); i++, cl2Iter++)
#endif
{
clarray2[i] = cl2Iter();
}
// use Stillman's algorithm
statistics[AttemptedStillmanSubsumptionTests] += 1;
totalstatistics[TotalAttemptedStillmanSubsumptionTests] += 1;
int status = ST(clarray1, clarray2, 1, 1, s);
if (status == OK && verbose)
{
cout << endl;
cout << "clause1 subsumes clause2 ..." << endl;
cout << "clause1: " << cl1 << endl;
cout << "clause2: " << cl2 << endl;
}
return(status);
}