pere(jean, jacques). pere(tom, jacques). pere(jacques, jean). mere(jean, annie). mere(jacques, marie). mere(anna, sylvie). parent(X,Y) :- pere(X,Y). parent(X,Y) :- mere(X,Y). grandpere(X,Y) :- parent(X,P), pere(P,Y). nul(K) :- egal(K,0). egal(X,X). my_member(X,[X|_]). my_member(X,[_|T]) :- my_member(X,T). my_append([],X,X). my_append([H|T], X, [H|R]) :- my_append(T,X,R).