def _truth(self, f: Formula, trace: FiniteTrace, position: int):
assert trace.alphabet == self.alphabet
truth = self._truth
pl = PL(self.alphabet)
if pl.is_formula(f):
return self.truth(PathExpressionEventually(f, LogicalTrue()),
trace, position)
elif isinstance(f, LogicalTrue):
return True
elif isinstance(f, Not):
return not self.truth(f.f, trace, position)
elif isinstance(f, And):
return self.truth(f.f1, trace, position) and self.truth(
f.f2, trace, position)
elif isinstance(f, PathExpressionEventually):
path = f.p
assert self._is_path(path)
if isinstance(path, PathExpressionTest):
return truth(path.f, trace, position) and truth(
f.f, trace, position)
elif isinstance(path, PathExpressionUnion):
return truth(PathExpressionEventually(path.p1, f.f), trace,
position) or truth(
PathExpressionEventually(path.p2, f.f), trace,
position)
elif isinstance(path, PathExpressionSequence):
return truth(
PathExpressionEventually(
path.p1, PathExpressionEventually(path.p2, f.f)),
trace, position)
elif isinstance(path, PathExpressionStar):
return truth(f.f, trace,
position) or (position < trace.last() and truth(
PathExpressionEventually(
path.p, PathExpressionEventually(
path, f.f)), trace, position)
and not self._is_testonly(path))
# path should be a Propositional Formula
else:
pl, I = PL._from_set_of_propositionals(trace.get(position),
trace.alphabet)
return position < trace.length() and pl.truth(
path, I) and truth(f.f, trace, position + 1)
else:
raise ValueError("Argument not a valid Formula")
class TestPL(unittest.TestCase):
"""Tests for `pythogic.ltlf` package."""
def setUp(self):
"""Set up test fixtures, if any."""
self.a_sym = Symbol("a")
self.b_sym = Symbol("b")
self.c_sym = Symbol("c")
self.alphabet = Alphabet({self.a_sym, self.b_sym, self.c_sym})
# Propositions
self.a = AtomicFormula(self.a_sym)
self.b = AtomicFormula(self.b_sym)
self.c = AtomicFormula(self.c_sym)
self.not_a = Not(self.a)
self.not_a_and_b = And(self.not_a, self.b)
self.not_a_or_c = Or(self.not_a, self.c)
self.true = TrueFormula()
self.false = FalseFormula()
self.symbol2truth = {
self.a_sym: True,
self.b_sym: False,
self.c_sym: True
}
self.I = PLInterpretation(self.alphabet, self.symbol2truth)
self.PL = PL(self.alphabet)
def tearDown(self):
"""Tear down test fixtures, if any."""
def test_truth(self):
self.assertTrue(self.PL.truth(self.a, self.I))
self.assertFalse(self.PL.truth(self.b, self.I))
self.assertTrue(self.PL.truth(self.c, self.I))
self.assertFalse(self.PL.truth(self.not_a, self.I))
self.assertFalse(self.PL.truth(self.not_a_and_b, self.I))
self.assertTrue(self.PL.truth(self.not_a_or_c, self.I))
self.assertTrue(self.PL.truth(self.true, self.I))
self.assertFalse(self.PL.truth(self.false, self.I))
