Consider the following premises. forall x_7: R_7(x_7) <-> S_7(x_7). R_7(a_7). Can we infer S_7(a_7) from them? If possible, name the inference rules being used at each step.
 From forall x_7: R_7(x_7) <-> S_7(x_7) we can infer R_7(a_7) <-> S_7(a_7) via universal instantiation. From R_7(a_7) <-> S_7(a_7) we can infer R_7(a_7) -> S_7(a_7) via biconditional elimination. Finally, from R_7(a_7) -> S_7(a_7), R_7(a_7) we can infer S_7(a_7) via modus ponens. Therefore, the answer is yes.