%Max of three
predicates
	max(integer, integer, integer, integer)

clauses
	max(X,Y,Z,X) :- X > Y, X > Z, !.
	max(X,Y,Z,Y) :- Y > Z, !.
	max(_,_,Z,Z).

goal
	max(1, 2, 3, R1),
	max(2, 1, 3, R2),
	max(1, 3, 2, R3),
	max(3, 1, 2, R4),
	max(2, 3, 1, R5),
	max(3, 2, 1, R6).