Re: where do I think wrong

On 14-03-14 07:54, Roelof Wobben wrote:
>>     half_or_full_siblings(X, Y) :-
>> >         (   same_father(X, Y),
>> > 	    X \== Y
>> > 	;   same_mother(X, Y),
>> > 	    \+ same_father(X, Y)
>> > 	).
>  
> Oke, I think this is what im searching for.
> One rule for full and half siblings. 
>  
> But I do not understand why "is not equal"  is used.

Because you don't usually want to say that a person is his or her own
sibling.

What I don't understand is why the X \== Y is only in the first
or-branch. IMHO it should also be in the second.