def unify(x, y, theta):
if theta is False:
return False
if (x == y):
return theta
if (Fact.is_variable(x)):
return unifyVar(x, y, theta)
elif (Fact.is_variable(y)):
return unifyVar(y, x, theta)
elif (Fact.is_fact(x) and Fact.is_fact(y)):
return unify(x.get_args(), y.get_args(),
unify(x.get_op(), y.get_op(), theta))
elif (Fact.is_list(x) and Fact.is_list(y)):
return unify(x[1:], y[1:], unify(x[0], y[0], theta))
return False
