Consider the following premises. ~u. p_12 <-> t. q -> p_12. t -> u. Can we infer ~q from them?
 From t -> u, ~u we can infer ~t. From p_12 <-> t we can infer p_12 -> t. From p_12 -> t, ~t we can infer ~p_12. Finally, from q -> p_12, ~p_12 we can infer ~q. Therefore, the answer is yes.