Consider the following premises. u -> q_1. p_5 <-> q. q_1 -> q. ~p_5. q -> u. Can we infer q_1 from them?
 From q -> u, u -> q_1 we can infer q -> q_1. From p_5 <-> q, ~p_5 we can infer ~q. From q -> q_1, q_1 -> q we can infer q <-> q_1. Finally, from q <-> q_1, ~q we can infer ~q_1, which contradicts q_1. Therefore, the answer is no.