Consider the following premises. u_2 <-> q_8. ~p_1. u -> u_2. p_1 <-> q_8. Can we infer ~u from them?
 From p_1 <-> q_8, ~p_1 we can infer ~q_8. From u_2 <-> q_8, ~q_8 we can infer ~u_2. Finally, from u -> u_2, ~u_2 we can infer ~u. Therefore, the answer is yes.