Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!uakari.primate.wisc.edu!ginosko!uunet!kddlab!icot32!hawley From: hawley@icot32.icot.junet (David John Hawley) Newsgroups: comp.lang.prolog Subject: Re: What does "extralogical" mean? Message-ID: <4872@icot32.icot.JUNET> Date: 28 Sep 89 02:39:29 GMT References: <2204@munnari.oz.au> Reply-To: hawley@icot31.icot.junet (David Hawley) Organization: Fifth Generation Computing Systems (ICOT), Tokyo, Japan Lines: 23 In article alberto@tove.umd.edu (Jose Alberto Fernandez R) writes: > >Well, your ISA(Term, Type) predicate could be as extra-logical as VAR(Term) >is. I think that it. For example, what happen if a variable is not >instanciated when the predicate P is called? > >There are 3 alternatives: >.... 4) The variable's tag is changed to Type without assigning a binding. Another way of putting it is that the variable is CONSTRAINED to be the given type. This is constraint LP and the CLP implementation techniques apply. Needless to say, it's apple-pie logical. -------- Eat this Pnews semi- intelligent software --------- David Hawley, 1st Lab, ICOT