equal(t,t). equal(f,f). ne(A,B) <= not equal(A,B). aND(X,Y) <= equal(X,t) and equal(Y,t). or(X,Y) <= ne(X,Y). or(X,Y) <= equal(X,Y) and equal(X,t).

Last updated 2002/03/18 © J.A.N. Lee, 2002.