person(earl).
person(dv).
person(melgibson).
person(jesus).
person(mike).
person(frank).
person(beth).
person(bacon).

parent(melgibson,jesus).
parent(beth,mike).
parent(dv,earl).
parent(frank,melgibson).
parent(dv,frank).
parent(earl,bacon).

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