Consider the following premises. R_7(a_7). forall x_7: R_7(x_7) <-> S_7(x_7). Can we infer ~S_7(a_7) from them?
 From forall x_7: R_7(x_7) <-> S_7(x_7) we can infer R_7(a_7) <-> S_7(a_7). From R_7(a_7) <-> S_7(a_7) we can infer R_7(a_7) -> S_7(a_7). Finally, from R_7(a_7) -> S_7(a_7), R_7(a_7) we can infer S_7(a_7), which contradicts ~S_7(a_7). Therefore, the answer is no.