False and null are the same thing. Undefined may be a property of a variable (what in Prolog-like languages would be called "variable" or "non-ground"). But,

False and null are the same thing. Undefined may be a property of a variable (what in Prolog-like languages would be called "variable" or "non-ground"). But, in this capacity it wouldn't be a value, it would be a property, similar to how in OO language you could say "it's a big class" (meaning it's a class that has more than five methods specializing on it), but you wouldn't start modeling your problem domain by creating BigClass class and then inheriting from it any time you want a class with more than five methods.