Consider the following premises. forall x_14: P_14(x_14). p_2 -> ~P_14(a_14). u -> p_2. Can we infer u from them? If possible, name the inference rules being used at each step.
 From forall x_14: P_14(x_14) we can infer P_14(a_14) via universal instantiation. From p_2 -> ~P_14(a_14), P_14(a_14) we can infer ~p_2 via modus tollens. Finally, from u -> p_2, ~p_2 we can infer ~u via modus tollens, which contradicts u. Therefore, the answer is no.