Consider the following premises. forall z_1: P(z_1). w_4 and u. Can we infer ~w_4 from them? If possible, name the inference rules being used at each step.
 From forall z_1: P(z_1) we can infer P(d) via universal instantiation. Finally, from w_4 and u we can infer w_4 via simplification, which contradicts ~w_4. Therefore, the answer is no.