% Topik dalam Pemrograman, Magister Ilmu Komputer

male(gerry).
male(frans).
male(husni).

female(riya).
female(indri).
female(reni).
female(alivia).

parent(alivia,frans).
parent(gerry,frans).
parent(gerry,riya).
parent(frans,reni).
parent(indri,husni).

father(X,Y):- parent(X,Y),male(X).
mother(X,Y):- parent(X,Y),female(X).
grandparent(X,Z):- parent(X,Y),parent(Y,Z).
offspring(X,Y):- parent(Y,X).
sister(X,Y):- parent(Z,X),parent(Z,Y),female(X),X\=Y.
pred(X,Y):-parent(X,Y).
pred(X,Y):-parent(X,Z),pred(Z,Y).
same(X,Y):- X=Y.
diff(X,Y):- not(same(X,Y)).

% written By Gerry Firmansyah