Consider the following premises. s_3 <-> s. ~p_8. p_8 <-> w. s_3 -> w. Can we infer ~s from them? If possible, name the inference rules being used at each step.
 From p_8 <-> w, ~p_8 we can infer ~w via biconditional elimination. From s_3 -> w, ~w we can infer ~s_3 via modus tollens. Finally, from s_3 <-> s, ~s_3 we can infer ~s via biconditional elimination. Therefore, the answer is yes.