[~p V (p-->q)]--> ~q A counter-example is when p and q are both true [~T V (T-->T)]--> ~T Replace ~T with F in both places: [F V (T-->T)]--> F Replace (T-->T) with T [F V T]--> F Replace [F V T] with T T--> F Replace that with F F. So it isn't a tautology. Edwin