Consider the following premises. forall x_9: P_9(x_9) <-> Q_9(x_9). P_9(e) -> Q_9(e). Can we infer P_9(e) <-> Q_9(e) from them? If possible, name the inference rules being used at each step.
 From forall x_9: P_9(x_9) <-> Q_9(x_9) we can infer forall x_9: Q_9(x_9) -> P_9(x_9) via universal biconditional elimination. From forall x_9: Q_9(x_9) -> P_9(x_9) we can infer Q_9(e) -> P_9(e) via universal instantiation. Finally, from P_9(e) -> Q_9(e), Q_9(e) -> P_9(e) we can infer P_9(e) <-> Q_9(e) via biconditional introduction. Therefore, the answer is yes.