Consider the following premises. s_2 -> R_10(a_10). forall x_10: R_10(x_10) -> S_10(x_10). S_10(a_10) -> s_2. Can we infer R_10(a_10) <-> s_2 from them? If possible, name the inference rules being used at each step.
 From forall x_10: R_10(x_10) -> S_10(x_10) we can infer R_10(a_10) -> S_10(a_10) via universal instantiation. From R_10(a_10) -> S_10(a_10), S_10(a_10) -> s_2 we can infer R_10(a_10) -> s_2 via transitivity. Finally, from R_10(a_10) -> s_2, s_2 -> R_10(a_10) we can infer R_10(a_10) <-> s_2 via biconditional introduction. Therefore, the answer is yes.