def kb():
kb = Knowledge()
l1 = lit(pred('y', 1), [var('X')])
l2 = lit(pred('x', 2), [var('X'), var('Y')])
l3 = lit(pred('z', 1), [var('Y')])
c1 = clause(l1, [l2, l3])
kb.assert_clause(c1)
assert kb.db
kb.retract_clause(c1)
assert not kb.db
def equals():
kb = Knowledge()
prover = Prover(kb)
l1 = lit(pred('y',1), [var('X')])
l2 = lit(pred('=',2), [var('X'), var('Y')])
l3 = lit(pred('z',1), [var('Y')])
c1 = clause(l1, [l2, l3])
kb.assert_clause(c1)
for v in ('foo', 'bar'):
kb.assert_clause(clause(lit(pred('z',1), [const(v)]), []))
query = lit(pred('y',1),[var('X')])
answer = prover.ask(query)
assert set(answer) == set([lit(pred('y',1), [const('foo')]), lit(pred('y',1), [const('bar')])])
def ask():
kb = Knowledge()
prover = Prover(kb)
l1 = lit(pred('y', 1), [var('X')])
l2 = lit(pred('x', 2), [var('X'), var('Y')])
l3 = lit(pred('z', 1), [var('Y')])
c1 = clause(l1, [l2, l3])
kb.assert_clause(c1)
for z in ('alice', 'mary', 'susan'):
head = lit(pred('z',1), [const(z)])
body = []
ca = clause(head, body)
kb.assert_clause(ca)
for x,y in [('alice', 'mary'), ('susan', 'mary')]:
head = lit(pred('x',2), [const(x), const(y)])
body = []
ca = clause(head, body)
kb.assert_clause(ca)
query = lit(pred('y',1),[var('X')])
answer = prover.ask(query)
assert set(answer) == set([lit(pred('y',1), [const('alice')]), lit(pred('y',1), [const('susan')])])
query = lit(pred('x',2), [var('X'), const('alice')])
answer = prover.ask(query)
assert not set(answer)
query = lit(pred('nothere',1), [var('X')])
answer = prover.ask(query)
assert not set(answer)
def clause_safe():
kb = Knowledge()
l1 = lit(pred('y', 1), [var('X')])
l2 = lit(pred('x', 2), [var('X'), var('Y')])
c1 = clause(l1, [l2])
c2 = clause(l2, [l1])
assert kb.is_safe(c1)
assert not kb.is_safe(c2)
l3 = lit(pred('z', 3), [var('A'), const('alice'), const('mary')])
c3 = clause(l3, [l3])
assert kb.is_safe(c3)
l4 = lit(pred('z', 1), [var('Z')], False)
c4 = clause(l1, [l2, l4])
assert not kb.is_safe(c4)
l5 = lit(pred('z', 1), [var('X')], False)
c5 = clause(l1, [l5])
assert not kb.is_safe(c5)
c6 = clause(l1, [l2, l5])
assert kb.is_safe(c6)
def primitives():
kb = Knowledge()
prover = Prover(kb)
def testpred(literal, prover):
if literal[0].is_const():
yield clause(literal)
else:
yield clause(lit(literal.pred, [const('foo')]))
yield clause(lit(literal.pred, [const('bar')]))
yield clause(lit(literal.pred, [const('baz')]))
kb.add_primitive(pred('testpred',1), testpred)
l1 = lit(pred('y', 1), [var('X')])
l2 = lit(pred('testpred', 1), [var('X')])
c1 = clause(l1, [l2])
kb.assert_clause(c1)
query = lit(pred('y',1),[var('X')])
answer = prover.ask(query)
assert set(answer) == set([lit(pred('y',1), [const('foo')]), lit(pred('y',1), [const('bar')]), lit(pred('y',1), [const('baz')])])
query = lit(pred('y',2), [const('twelve'), var('X')])
answer = prover.ask(query)
assert not set(answer)
kb.assert_clause(clause(lit(pred('testpred', 1), [const('quux')]), []))
query = lit(pred('y',1),[var('X')])
answer = prover.ask(query)
assert set(answer) == set([lit(pred('y',1), [const('foo')]), lit(pred('y',1), [const('bar')]), lit(pred('y',1), [const('baz')]), lit(pred('y',1), [const('quux')])])
query = lit(pred('y',2), [const('twelve'), var('X')])
answer = prover.ask(query)
assert not set(answer)