def new_literals(self, clause):
"""Generates new literals based on known predicate symbols.
Generated literal must share atleast one variable with clause"""
share_vars = variables(clause[0])
for l in clause[1]:
share_vars.update(variables(l))
for pred, arity in self.pred_syms:
new_vars = {standardize_variables(expr('x')) for _ in range(arity - 1)}
for args in product(share_vars.union(new_vars), repeat=arity):
if any(var in share_vars for var in args):
yield Expr(pred, *[var for var in args])
def new_literals(self, clause):
"""Generate new literals based on known predicate symbols.
Generated literal must share at least one variable with clause"""
share_vars = variables(clause[0])
for l in clause[1]:
share_vars.update(variables(l))
for pred, arity in self.pred_syms:
new_vars = {standardize_variables(expr('x')) for _ in range(arity - 1)}
for args in product(share_vars.union(new_vars), repeat=arity):
if any(var in share_vars for var in args):
# make sure we don't return an existing rule
if not Expr(pred, args) in clause[1]:
yield Expr(pred, *[var for var in args])
def fol_bc_or(KB, goal, theta):
for rule in KB.fetch_rules_for_goal(goal):
lhs, rhs = parse_definite_clause(standardize_variables(rule))
for theta1 in fol_bc_and(KB, lhs, unify(rhs, goal, theta)):
yield ([(goal, theta1[0])], theta1[1])
def fol_bc_or(KB, goal, theta):
for rule in KB.fetch_rules_for_goal(goal):
lhs, rhs = parse_definite_clause(standardize_variables(rule))
for theta1 in fol_bc_and(KB, lhs, unify(rhs, goal, theta)):
yield ([(goal, theta1[0])], theta1[1])
