Consider the following premises. forall x: ~P_2(x). p_2 -> P_2(a_14). u -> p_2. Can we infer ~u from them?
 From forall x: ~P_2(x) we can infer ~P_2(a_14). From p_2 -> P_2(a_14), ~P_2(a_14) we can infer ~p_2. Finally, from u -> p_2, ~p_2 we can infer ~u. Therefore, the answer is yes.