Re: How to use not in gprolog?

[Jean Michel LECONTE]

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.
not(Goal):-true.


Regards,

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?