mother(mary,tom). mother(mary,jane). mother(mary,fred). father(tom,jim). father(tom,sue). father(fred,cecil). female(mary). female(jane). male(tom). male(jim). female(sue). male(cecil). male(fred). parent(Parent,Child):- father(Parent,Child). parent(Parent,Child):- mother(Parent,Child). son(Son,Person):- parent(Person,Son), male(Son). daughter(Dau,Person):- parent(Person,Dau), female(Dau).