Consider the following premises. p_3 <-> s_3. p_3 or q_7. s_3 or ~q_7. Can we infer ~s_3 from them?
 From s_3 or ~q_7 we can infer q_7 -> s_3. From p_3 <-> s_3 we can infer p_3 -> s_3. Finally, from p_3 -> s_3, q_7 -> s_3, p_3 or q_7 we can infer s_3, which contradicts ~s_3. Therefore, the answer is no.