def __backward_chaining_and(kb, goals, theta):
if theta is problem.FAILURE:
return problem.FAILURE
if len(goals) == 0:
return theta
for goal in goals:
theta = __backward_chaining_or(kb, substitute(goal, theta), theta)
return theta
def __backward_chaining_and(kb, goals, theta):
if theta is problem.FAILURE:
return problem.FAILURE
if len(goals) == 0:
return theta
for goal in goals:
theta = __backward_chaining_or(kb, substitute(goal, theta), theta)
return theta
def __standardize_resolvent(resolvent, theta):
replacer = StandartizationReplacer("x")
result = set()
for index, disjunct in enumerate(resolvent):
# Do we need standartization? No, we don't
result.add(substitute(disjunct, theta))
StandartizationReplacer.GlobalIndex = replacer.index
resolvent = frozenset(result)
return resolvent
def __standardize_resolvent(resolvent, theta):
replacer = StandartizationReplacer("x")
result = set()
for index, disjunct in enumerate(resolvent):
# Do we need standartization? No, we don't
result.add(substitute(disjunct, theta))
StandartizationReplacer.GlobalIndex = replacer.index
resolvent = frozenset(result)
return resolvent
