Consider the following premises. q -> u. ~t. p_1 <-> t. p_1 <-> u. Can we infer ~q from them?
 From p_1 <-> t, ~t we can infer ~p_1. From p_1 <-> u, ~p_1 we can infer ~u. Finally, from q -> u, ~u we can infer ~q. Therefore, the answer is yes.