Consider the following premises. forall x_7: R_2(x_7) <-> S_7(x_7). ~w. R_2(j) <-> w. Can we infer S_7(j) from them? If possible, name the inference rules being used at each step.
 From forall x_7: R_2(x_7) <-> S_7(x_7) we can infer R_2(j) <-> S_7(j) via universal instantiation. From R_2(j) <-> w, ~w we can infer ~R_2(j) via biconditional elimination. Finally, from R_2(j) <-> S_7(j), ~R_2(j) we can infer ~S_7(j) via biconditional elimination, which contradicts S_7(j). Therefore, the answer is no.