Consider the following premises. p_9 <-> s. s_3 <-> u_2. u_2 -> p_9. ~s. Can we infer s_3 from them?
 From p_9 <-> s, ~s we can infer ~p_9. From u_2 -> p_9, ~p_9 we can infer ~u_2. Finally, from s_3 <-> u_2, ~u_2 we can infer ~s_3, which contradicts s_3. Therefore, the answer is no.