Consider the following premises. forall x_18: P_18(x_18). t_4 -> ~P_18(a_18). ~t_4 -> w. Can we infer w from them?
 From forall x_18: P_18(x_18) we can infer P_18(a_18). From t_4 -> ~P_18(a_18), P_18(a_18) we can infer ~t_4. Finally, from ~t_4 -> w, ~t_4 we can infer w. Therefore, the answer is yes.