Consider the following premises. p_2 -> r_4. ~p_2 -> w. ~s. s <-> r_4. Can we infer w from them? If possible, name the inference rules being used at each step.
 From s <-> r_4, ~s we can infer ~r_4 via biconditional elimination. From p_2 -> r_4, ~r_4 we can infer ~p_2 via modus tollens. Finally, from ~p_2 -> w, ~p_2 we can infer w via modus ponens. Therefore, the answer is yes.