mother(dorothy,steve).
father(alan,steve).
mother(helen,dorothy).
father(konrad,dorothy).
mother('mary frances',alan).
father(austin,alan).
mother(carol,deborah).
father(robert,deborah).
mother(dorothy,paul).
father(alan,paul).
mother(eugenia,jeb).
father(alan,jeb).
mother('mary frances',will).
father(austin,will).
mother('mary frances',jim).
father(austin,jim).

parent(X,Y) :- mother(X,Y).
parent(X,Y) :- father(X,Y).

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