Consider the following premises. p_9 <-> s. u_3 <-> s. ~p_9. Can we infer ~u_3 from them?
 From p_9 <-> s we can infer s -> p_9. From s -> p_9, ~p_9 we can infer ~s. Finally, from u_3 <-> s, ~s we can infer ~u_3. Therefore, the answer is yes.