def test_apply_should_succeed_if_new_clauses_are_correct(self):
rewrite_rules3 = paracontrol.createRewriteRule(self.c6)
to = ['add', 'B', 'A']
frm = ['add', 'A', 'B']
expectedLiteral = literals.Literal([
'=', ['subtract', ['add', 'B', 'A'], 'C'],
['add', ['subtract', 'A', 'C'], 'B']
])
expectedClause = clauses.Clause([expectedLiteral])
rewrite_rule = rewriterule.rewriteRule(frm, to, [], self.c1)
res = rewrite_rule.apply(self.c3)
self.assertTrue(expectedClause.compare(res[0]))
res2 = rewrite_rules3[1].apply(self.c7)
print(res2)
def test_replaceSubstitute_should_succeed_if_new_clause_is_correct(self):
subst = substitutions.Substitution()
pos = position.Position(subst, [
0,
1,
1,
])
clause = self.c3.replaceSubstitute(pos, ['add', 'B', 'A'])
expectedLiteral = literals.Literal([
'=', ['subtract', ['add', 'B', 'A'], 'C'],
['add', ['subtract', 'A', 'C'], 'B']
])
expectedClause = clauses.Clause([expectedLiteral])
self.assertEqual(expectedClause.compare(clause), True)
def factor(clause, lit1, lit2):
"""
Check if it is possible to form a factor between lit1 and lit2. If
yes, return it, otherwise return None.
"""
l1 = clause.getLiteral(lit1)
l2 = clause.getLiteral(lit2)
if l1.isNegative() != l2.isNegative():
return None
sigma = mgu(l1.atom, l2.atom)
if sigma == None:
return None
lits = [l.instantiate(sigma) for l in clause.literals if l != l2]
res = clauses.Clause(lits)
res.removeDupLits()
res.setDerivation(flatDerivation("factor", [clause]))
return res
def resolution(clause1, lit1, clause2, lit2):
"""
Implementation of the Resolution rule. lit1 and lit2 are indices
of literals in clause1 and clause2, respectively, so clause1|lit1
and clause2|lit2 are literals.
Try to resolve clause1|lit1 against clause2|lit2. If this is
possible, return the resolvent. Otherwise, return None.
"""
l1 = clause1.getLiteral(lit1)
l2 = clause2.getLiteral(lit2)
if l1.isNegative() == l2.isNegative():
return None
sigma = mgu(l1.atom, l2.atom)
if sigma is None:
return None
lits1 = [l.instantiate(sigma) for l in clause1.literals if l!=l1]
lits2 = [l.instantiate(sigma) for l in clause2.literals if l!=l2]
lits1.extend(lits2)
res = clauses.Clause(lits1)
res.removeDupLits()
res.setDerivation(flatDerivation("resolution", [clause1, clause2]))
return res