child(john,sue). child(jane,sue). child(sue,george). child(john,sam). child(jane,sam). child(sue,gina). child(mary,gina). % new child(mary,george). % new child(henry,mary). % new child(henry,paul). % new male(john). male(sam). male(george). female(sue). female(jane). female(june). parent(Y,X) :- child(X,Y). father(Y,X) :- child(X,Y), male(Y). opp_sex(X,Y) :- male(X), female(Y). opp_sex(Y,X) :- male(X), female(Y). grand_father(X,Z) :- father(X,Y), parent(Y,Z). % new: definition of ancestor(X,Y) meaning X is an ancestor of Y ancestor(X,Y) :- child(Y,X). ancestor(X,Y) :- child(Y,Z), ancestor(X,Z). % add your code here