Untitled

mother(X,Y):- /* mother of X is Y */
    parent(X,Y),
    female(Y).

father(X,Y):- /* father of X is Y */
    parent(X,Y),
    male(Y).

husbandwife(X,Y) :- /* X is a husband of Y wife */
    father(Z,X),
    mother(Z,Y),
	X \= Y.

sibling(X,Y) :- /* X is a sibling of Y */
    father(X,Z),
    father(Y,Z),
    X \= Y.

grandfather(X,Y):- /* X is grandfather of Y */
    parent(Y,Z),
    parent(Z,X),
	male(X).

grandmother(X,Y):-
    parent(Y,Z),
    parent(Z,X),
    female(X).

aunt(X,Y):- /* X is an aunt of Y */
    parent(Y,Z),
    sibling(X,Z),
    female(X).
    
uncle(X,Y):- /* X is an uncle of Y */
    parent(Y,Z), sibling(X,Z),
	male(X).

cousinbrother(X,Y):- /* X is cousin brother of Y */
    parent(X,Z),
    parent(Y,W),
    sibling(Z,W),
	male(X).

cousinsister(X,Y):- /* X is cousin sister of Y */
    parent(X,Z),
    parent(Y,W),
    sibling(Z,W),
    female(X).

cousin(X,Y):- /* X is cousin of Y */
    parent(X,Z),
    parent(Y,W),
    sibling(Z,W).