Crossing bk


person(a).

person(b).

person(c).

person(d).

speed(a,1).

speed(b,2).

speed(c,5).

speed(d,10).

max(A,B,A) :- A >=B, speed(_,A), speed(_,B).

max(A,B,B) :- B > A, speed(_,A), speed(_,B).