Re: How to use not in gprolog?

[ED-DBALI AbdelAli]

Carfield Yim a écrit :
> 
> 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?

Try the negation by failure (\+) (also called "not provable". see 6.18.2
in the manual):

\+ member(Y,T) will succed if Y is not member of T.

Hope this help.

                Ali.