def test_simplify_every_child(lexicon):
# (LP.LQ.Ax.P(x) -> Q(x))(Lx.Child(x)) -> LQ.Ax.Child(x) -> Q(x)
tree = Call(lexicon["every"][0].formula, lexicon["child"][0].formula)
assert tree.simplify() == Lambda(
"Q",
ForAll("x",
IfThen(Call(Var("Child"), Var("x")), Call(Var("Q"), Var("x")))))
def test_translate_every_child_is_good(lexicon):
nodes = translate_sentence("every child is good", lexicon)
assert len(nodes) == 1
node = nodes[0]
assert node.text == "every child is good"
assert node.formula == ForAll(
"x", IfThen(Call(Var("Child"), Var("x")), Call(Var("Good"), Var("x"))))
assert node.type == TYPE_TRUTH_VALUE
def test_replace_variable_in_quantifiers():
tree = ForAll(
"x",
Or(And(ForAll("b", Var("b")), Exists("b", Var("b"))), Exists("y", Var("b"))),
)
assert tree.replace_variable("b", Var("bbb")) == ForAll(
"x",
Or(And(ForAll("b", Var("b")), Exists("b", Var("b"))), Exists("y", Var("bbb"))),
)
def test_nested_exists_and_for_all_to_str():
assert str(And(ForAll("x", Var("x")), Exists("x", Var("x")))) == "[∀ x.x] & [∃ x.x]"
def test_for_all_to_str():
tree = ForAll("x", Call(Var("P"), Var("x")))
assert str(tree) == "∀ x.P(x)"
assert tree.ascii_str() == "Ax.P(x)"
def test_everyone_is_human_is_true():
formula = ForAll("x", Call(Var("Human"), Var("x")))
assert interpret_formula(formula, test_model)
def test_everyone_is_bad_is_false():
formula = ForAll("x", Call(Var("Bad"), Var("x")))
assert not interpret_formula(formula, test_model)
def test_parsing_for_all():
assert parse_formula("Ax.x & y") == ForAll("x", And(Var("x"), Var("y")))
assert parse_formula("A x.x & y") == ForAll("x", And(Var("x"), Var("y")))
assert parse_formula("∀x.x & y") == ForAll("x", And(Var("x"), Var("y")))