Consider the following premises. exists x_2: Q(x_2) -> P_4(x_2). forall x_2: P_4(x_2) <-> Q(x_2). Can we infer forall x_2: P_4(x_2) <-> Q(x_2) from them? If possible, name the inference rules being used at each step.
That is one of the premises. Therefore, the answer is yes.