Consider the following premises. S_14(a_15) -> s. forall x_14: P_15(x_14) -> S_14(x_14). forall x_15: P_15(x_15). Can we infer ~s from them? If possible, name the inference rules being used at each step.
 From forall x_15: P_15(x_15) we can infer P_15(a_15) via universal instantiation. From forall x_14: P_15(x_14) -> S_14(x_14) we can infer P_15(a_15) -> S_14(a_15) via universal instantiation. From P_15(a_15) -> S_14(a_15), P_15(a_15) we can infer S_14(a_15) via modus ponens. Finally, from S_14(a_15) -> s, S_14(a_15) we can infer s via modus ponens, which contradicts ~s. Therefore, the answer is no.