Re: where do I think wrong

On 13-03-14 09:04, Roelof Wobben wrote:
> have_siblings(C) :-
>     is_father(X,C),
>     is_father(X,S); 
>     is_mother(Y,S), 
>     is_mother(Y,C), 
>     C \= S,
>     write(S).
> 
> So if a father of a child(C)  is equal to the father of a sibling(S) or the mother of a child is equal to the mother of a sibling.
> But nothing gets found then. 

The scope of your "or" is wrong. a,b;c,d,e,f is equivalent to
(a,b);(c,d,e,f), but I think you need (a,b;c,d),e,f.