def delta(self, i: PLInterpretation, epsilon=False) -> PLFormula:
f = self.to_nnf()
d = f._delta(i, epsilon)
if epsilon:
# By definition, if epsilon=True, then the result must be either PLTrue or PLFalse
# Now, the output is a Propositional Formula with only PLTrue or PLFalse as atomics
# Hence, we just evaluate the formula with a dummy PLInterpretation
d = PLTrue() if d.truth(None) else PLFalse()
return d
def delta(self,
i: PropositionalInterpretation,
epsilon=False) -> PLFormula:
"""Apply the delta function."""
f = self.to_nnf()
d = f._delta(i, epsilon=epsilon)
if epsilon:
# By definition, if epsilon=True, then the result must be either True or False.
# The output is a Propositional Formula with only True or False as atomics.
# Hence, we just evaluate the formula with the empty propositional interpretation.
d = PLTrue() if d.truth({}) else PLFalse()
return d
