Consider the following premises. S_7(a_7). forall x_7: R_7(x_7) <-> S_7(x_7). Can we infer R_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 S_7(a_7) -> R_7(a_7) via biconditional elimination. Finally, from S_7(a_7) -> R_7(a_7), S_7(a_7) we can infer R_7(a_7) via modus ponens. Therefore, the answer is yes.