Consider the following premises. forall x_7: P_7(x_7) or ~Q_7(x_7). P_7(g_4) -> Q_7(g_4). Can we infer Q_7(g_4) <-> P_7(g_4) from them? If possible, name the inference rules being used at each step.
 From forall x_7: P_7(x_7) or ~Q_7(x_7) we can infer forall x_7: Q_7(x_7) -> P_7(x_7) via universal rewriting. From forall x_7: Q_7(x_7) -> P_7(x_7) we can infer Q_7(g_4) -> P_7(g_4) via universal instantiation. Finally, from Q_7(g_4) -> P_7(g_4), P_7(g_4) -> Q_7(g_4) we can infer Q_7(g_4) <-> P_7(g_4) via biconditional introduction. Therefore, the answer is yes.