Consider the following premises. forall x_17: U(x_17) -> S_17(x_17). S_17(j) <-> s_2. s_2 -> U(j). Can we infer s_2 -> S_17(j) from them? If possible, name the inference rules being used at each step.
 From forall x_17: U(x_17) -> S_17(x_17) we can infer U(j) -> S_17(j) via universal instantiation. Finally, from s_2 -> U(j), U(j) -> S_17(j) we can infer s_2 -> S_17(j) via transitivity. Therefore, the answer is yes.