Consider the following premises. forall x_9: Q_9(x_9) <-> P_9(x_9). forall x_9: P_9(x_9) or ~Q_9(x_9). Can we infer ~(Q_9(a_2) -> P_9(a_2)) from them? If possible, name the inference rules being used at each step.
That contradicts the premises. Therefore the answer is no.