/* ------------------------------------------------
%   Getting Started with SWI-Prolog
%   Family Relations (family.pl)
  -------------------------------------------------- */


male(john).
male(paul).

female(lisa).
female(mary).


fatherOf(john,paul).
fatherOf(mary,paul).

motherOf(john,lisa).
motherOf(mary,lisa).


parentOf(X,Y):-
	fatherOf(X,Y).

parentOf(X,Y):-
	motherOf(X,Y).