Consider the following premises. w_3 -> R_13(a_13). w_3. forall x_13: ~R_13(x_13). Can we infer u from them?
 From forall x_13: ~R_13(x_13) we can infer ~R_13(a_13). From w_3 we can infer w_3 or u. From w_3 -> R_13(a_13), ~R_13(a_13) we can infer ~w_3. Finally, from w_3 or u, ~w_3 we can infer u. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.