def test_superexpansion_revision(self):
bb = self.belief_base
bb2 = BeliefBase(self.belief_base.beliefs,
selection_function=select_largest_set)
phi = self.p
xi = self.q
# Phi is not a member of Belief Base
bb.revise(Belief(And(phi, xi)))
bb2.revise(Belief(phi))
bb2.expand(Belief(xi))
assert bb.beliefs.issubset(bb2.beliefs)
def test_extensionality_revision(self):
bb = self.belief_base
bb2 = BeliefBase(self.belief_base.beliefs,
selection_function=select_largest_set)
phi = Or(self.p, self.q)
xi = Or(self.p, self.q)
# Phi is not a member of Belief Base
if not entails({}, Biconditional(phi, xi)):
assert False
bb.revise(Belief(phi))
bb2.revise(Belief(xi))
assert bb == bb2
def test_subexpansion_revision(self):
bb = self.belief_base
bb2 = BeliefBase(self.belief_base.beliefs,
selection_function=select_largest_set)
phi = self.p
xi = self.q
# Phi is not a member of Belief Base
bb.revise(Belief(phi))
if entails(bb.get_clauses(), Not(xi)):
assert False
bb.expand(Belief(xi))
bb2.revise(Belief(And(phi, xi)))
assert bb.beliefs.issubset(bb2.beliefs)