Consider the following premises. ~u. p_8 <-> u. s_2 -> p_8. Can we infer ~s_2 from them? If possible, name the inference rules being used at each step.
 From p_8 <-> u we can infer p_8 -> u via biconditional elimination. From p_8 -> u, ~u we can infer ~p_8 via modus tollens. Finally, from s_2 -> p_8, ~p_8 we can infer ~s_2 via modus tollens. Therefore, the answer is yes.