Consider the following premises. p_9 <-> s_2. s_2 or ~p_9. Can we infer ~(s_2 <-> p_9) from them?
 From p_9 <-> s_2 we can infer s_2 -> p_9. From s_2 or ~p_9 we can infer p_9 -> s_2. Finally, from s_2 -> p_9, p_9 -> s_2 we can infer s_2 <-> p_9, which contradicts ~(s_2 <-> p_9). Therefore, the answer is no.