Consider the following premises. forall x_9: P_9(x_9) <-> Q_9(x_9). forall x_9: ~Q_9(x_9). u <-> P_9(j_1). Can we infer forall x_9: P_9(x_9) <-> Q_9(x_9) from them? If possible, name the inference rules being used at each step.
That is one of the premises. Therefore, the answer is yes.