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Re: How to use not in gprolog?

From: Jean Michel LECONTE
Subject: Re: How to use not in gprolog?
Date: Tue, 30 Oct 2001 14:21:24 +0000

u can use the predicate \+(Goal) wich means not provable

not/1 isnt a builtin in GNU Prolog

a possible definition of not/1 is :

not(Goal):-Goal,!, fail.


Jean Michel LECONTE

Carfield Yim wrote  :
> Hi, I need to find the negation of a clause, e.g.:
> e.g: if Z is a member of list T and Y is not a member of T, member(Z,T)
> should return true and member(Y,T) should return false. I would like to get
> the negation of this clause, i.e.: not(member(Z,T)) return false and
> not(member(Y,T)) return true. But it doesn't work. So I try
> member(X,T)\=true. and once(member(X,T))\=true. But both don't work.
> So I would like to ask how to get the negation of a clause?

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