Consider the following premises. forall x_10: U(x_10) -> S_10(x_10). S_10(j) <-> U(j). Can we infer U(j) <-> S_10(j) from them?
 From forall x_10: U(x_10) -> S_10(x_10) we can infer U(j) -> S_10(j). From S_10(j) <-> U(j) we can infer S_10(j) -> U(j). Finally, from U(j) -> S_10(j), S_10(j) -> U(j) we can infer U(j) <-> S_10(j). Therefore, the answer is yes.