Consider the following premises. w -> ~s_3. q or s_3. ~q. Can we infer w from them? If possible, name the inference rules being used at each step.
 From q or s_3, ~q we can infer s_3 via disjunctive syllogism. Finally, from w -> ~s_3, s_3 we can infer ~w via modus tollens, which contradicts w. Therefore, the answer is no.