Consider the following premises. ~p. p_4 -> t. t -> p. s_2. Can we infer ~p_4 from them? If possible, name the inference rules being used at each step.
 From t -> p, ~p we can infer ~t via modus tollens. Finally, from p_4 -> t, ~t we can infer ~p_4 via modus tollens. Therefore, the answer is yes.