Consider the following premises. R_1(a_9) -> R(a_9). forall z: R(z) <-> R_1(z). Can we infer R(a_9) -> R_1(a_9) from them? If possible, name the inference rules being used at each step.
 From forall z: R(z) <-> R_1(z) we can infer R(a_9) <-> R_1(a_9) via universal instantiation. Finally, from R(a_9) <-> R_1(a_9) we can infer R(a_9) -> R_1(a_9) via biconditional elimination. Therefore, the answer is yes.