Consider the following premises. Q(a_12) -> u. w -> u. forall y: Q(y). Can we infer u from them?
 From forall y: Q(y) we can infer Q(a_12). From Q(a_12) we can infer Q(a_12) or w. Finally, from Q(a_12) -> u, w -> u, Q(a_12) or w we can infer u. Therefore, the answer is yes.