Consider the following premises. W_4(a_7) -> S_14(a_14). ~R_14(a_14). forall x_7: W_4(x_7) <-> S_7(x_7). forall x_14: R_14(x_14) <-> S_14(x_14). Can we infer S_7(a_7) from them? If possible, name the inference rules being used at each step.
 From forall x_14: R_14(x_14) <-> S_14(x_14) we can infer R_14(a_14) <-> S_14(a_14) via universal instantiation. From R_14(a_14) <-> S_14(a_14), ~R_14(a_14) we can infer ~S_14(a_14) via biconditional elimination. From forall x_7: W_4(x_7) <-> S_7(x_7) we can infer W_4(a_7) <-> S_7(a_7) via universal instantiation. From W_4(a_7) -> S_14(a_14), ~S_14(a_14) we can infer ~W_4(a_7) via modus tollens. Finally, from W_4(a_7) <-> S_7(a_7), ~W_4(a_7) we can infer ~S_7(a_7) via biconditional elimination, which contradicts S_7(a_7). Therefore, the answer is no.