def test_prove_no_relevant_clauses(self):
joe = logic.Atom('joe')
judy = logic.Atom('judy')
jorge = logic.Atom('jorge')
x = logic.Var('x')
db = {'likes': []}
db['likes'].append(logic.Clause(logic.Relation('likes', (joe, x)),
[logic.Relation('likes', (x, joe)),
logic.Relation('hates', (judy, x))]))
db['likes'].append(logic.Clause(logic.Relation('likes', (jorge, judy))))
goal = logic.Relation('hates', (joe, x))
bindings = logic.prove(goal, {}, db)
self.assertFalse(bindings)
def test_prove_no_subgoals_required(self):
joe = logic.Atom('joe')
judy = logic.Atom('judy')
jorge = logic.Atom('jorge')
x = logic.Var('x')
db = {'likes': []}
db['likes'].append(logic.Clause(logic.Relation('likes', (joe, x)),
[logic.Relation('likes', (x, joe)),
logic.Relation('hates', (judy, x))]))
db['likes'].append(logic.Clause(logic.Relation('likes', (jorge, judy))))
goal = logic.Relation('likes', (jorge, x))
bindings = logic.prove(goal, {}, db)
self.assertEqual({x: judy}, bindings)
def test_prove_subgoals_required_fail(self):
joe = logic.Atom('joe')
judy = logic.Atom('judy')
jorge = logic.Atom('jorge')
x = logic.Var('x')
db = {'likes': [], 'hates': []}
db['likes'].append(
logic.Clause(logic.Relation('likes', (joe, x)), [
logic.Relation('likes', (x, joe)),
logic.Relation('hates', (judy, x))
]))
db['likes'].append(logic.Clause(logic.Relation('likes', (jorge, joe))))
db['hates'].append(logic.Clause(logic.Relation('hates', (judy, joe))))
goal = logic.Relation('likes', (joe, jorge))
bindings = logic.prove(goal, {}, db)
self.assertFalse(bindings)
