Consider the following premises. P(a_5). forall x_5: P(x_5) -> S_5(x_5). Can we infer S_5(a_5) from them? If possible, name the inference rules being used at each step.
 From forall x_5: P(x_5) -> S_5(x_5) we can infer P(a_5) -> S_5(a_5) via universal instantiation. Finally, from P(a_5) -> S_5(a_5), P(a_5) we can infer S_5(a_5) via modus ponens. Therefore, the answer is yes.