[net.lang.prolog] "For All" in Prolog - Thanks

baldwin@rochester.ARPA (Douglas Baldwin) (09/23/86)

        Thanks to everyone who answered my question a few
weeks ago about implementing "for all" in Prolog. The general
consensus was that
        forall X in S, Body
can be re-expressed as
        "there is no X in S such that Body doesn't hold"
which can be written in Prolog as
        not( In_S(X), not Body(X,...) )
(This is a mix of syntaxes from several Prologs, my original
description of the problem, etc., but the idea is clear I
hope.) This is clearly what I need. Special thanks to
Lee Naish, David Morley, Heiner Marxen and Steve Jones for
their discussions of this solution.