male(tom_sr).
male(tom_jr).
male(mickey).
male(bill).
male(doug).
male(ben).
male(mike).
male(steve).
male(jack).
male(lucas).
male(bo).
male(jeremy).
male(jack_jr).
male(david).
male(will).
male(shawn).
male(zack).
male(scotty).
female(alice).
female(kitty).
female(maggie).
female(marie).
female(laura).
female(addie).
female(jessica).
female(sarah).
female(melissa).
female(julie).
female(sandy).
female(jennifer).
female(hope).
female(abby).
female(chelsea).
female(trish).
parent(tom_sr,marie).
parent(tom_sr,tom_jr).
parent(tom_sr,mickey).
parent(tom_sr,addie).
parent(alice,marie).
parent(alice,tom_jr).
parent(alice,mickey).
parent(alice,addie).
parent(tom_jr,sandy).
parent(kitty,sandy).
parent(mickey,sarah).
parent(mickey,melissa).
parent(maggie,sarah).
parent(maggie,melissa).
parent(marie,jessica).
parent(laura,mike).
parent(laura,jennifer).
parent(bill,mike).
parent(bill,jennifer).
parent(bill,lucas).
parent(doug,hope).
parent(addie,hope).
parent(addie,julie).
parent(addie,steve).
parent(ben,julie).
parent(ben,steve).
parent(mike,jeremy).
parent(julie,david).
parent(jack,jack_jr).
parent(jack,abby).
parent(jennifer,jack_jr).
parent(jennifer,abby).
parent(lucas,will).
parent(bo,chelsea).
parent(bo,shawn).
parent(bo,zack).
parent(hope,shawn).
parent(hope,zack).
parent(david,scotty).
parent(trish,scotty).

diff(X,Y) :- X \== Y.