Consider the following premises. ~p_12. w -> s. p_12 <-> s. w or q. Can we infer ~q from them?
 From p_12 <-> s, ~p_12 we can infer ~s. From w -> s, ~s we can infer ~w. Finally, from w or q, ~w we can infer q, which contradicts ~q. Therefore, the answer is no.