family.pl

% Facts
parent(dirce, gislene).
parent(dirce, irair).
parent(valdemar, gislene).
parent(valdemar, irair).
parent(gislene, alexandre).
parent(gislene, fakebrother).
parent(irair, fernando).

% Rules
child(X, Y) :- parent(Y, X), X\=Y.
grandchild(X, Y) :- parent(Z, X), parent(Y, Z), X\=Y.
sibling(X, Y) :- parent(Z, X), parent(Z, Y), X\=Y.
nephew(X, Y) :- parent(W, X), sibling(W, Y), X\=Y.
cousin(X, Y) :- parent(W, X), sibling(W, Z), child(Y, Z), X\=Y.

% Queries
?- child(alexandre, A),
    write('Alexandre é filho de '), writeln(A).

?- grandchild(alexandre, A),
    write('Alexandre é neto de '), writeln(A).
        
?- sibling(alexandre, A),
    write('Alexandre é irmão de '), writeln(A).
    
?- nephew(alexandre, A),
    write('Alexandre é sobrinho de '), writeln(A).
    
?- cousin(alexandre, A),
    write('Alexandre é primo de '), writeln(A).