How do i create a brother predicate for prolog?
<p>I have been told to create a brother predicate which finds out if a brother has a sibling. <code>Brother(B, S) :-</code>. I know that you would need to find out if they have the same parents but i am not sure how to do this. </p>

<pre><code>father(dan,phil).
father(dan,jack).
father(dan,christine).
father(phil,kenton).
father(phil,shula).
father(phil,david).
father(phil,elizabeth).
father(jack,lillian).
father(jack,tony).
father(jack,jenny).
father(tony,tommy).
father(tony,helen).
father(tony,john).
father(roger,adam).
father(roger,debbie).
father(brian,kate).
father(david,pip).
father(david,josh).
father(mark,daniel).

mother(doris,phil).
mother(doris,jack).
mother(doris,christine).
mother(jill,kenton).
mother(jill,shula).
mother(jill,david).
mother(jill,elizabeth).
mother(peggy,lillian).
mother(peggy,tony).
mother(peggy,jenny).
mother(pat,tommy).
mother(pat,helen).
mother(pat,john).
mother(jenny,adam).
mother(jenny,debbie).
mother(jenny,kate).
mother(ruth,pip).
mother(ruth,josh).
mother(shula,daniel).

male(dan).
male(phil).
male(jack).
male(kenton).
male(david).
male(tony).
male(brian).
male(roger).
male(mark).
male(john).
male(tommy).
male(adam).
male(daniel).
male(josh).

female(doris).
female(jill).
female(peggy).
female(christine).
female(shula).
female(ruth).
female(elizabeth).
female(lillian).
female(pat).
female(jenny).
female(helen).
female(debbie).
female(kate).
female(pip).

dead(dan).
dead(doris).
dead(jack).
dead(mark).
dead(john).
dead(fred).


parent(X,Y) :-
        father(X,Y); mother(X,Y).

grandfather(X,Y) :-
        father(X,Z), mother(Z,Y).
grandfather(X,Y) :-
        father(X,Z), father(Z,Y).

ancestor(X,Y) :- parent(X,Y).
ancestor(X,Y) :- parent(X,Z), ancestor(Z,Y).

archer(dan).
archer(X) :- father(P,X), archer(P).
</code></pre>

<p>This is the document i have which defines parents, grandfather etc. 
I need to create a brother predicate which sits as brother(B being brother, S being sibling). For example brother(liam, georgia). Liam is the brother of Georgia should be true </p>