Consider the following premises. q_8 -> s_2. q_4 <-> q_8. ~s_2. Can we infer ~q_4 from them?
 From q_4 <-> q_8 we can infer q_4 -> q_8. From q_8 -> s_2, ~s_2 we can infer ~q_8. Finally, from q_4 -> q_8, ~q_8 we can infer ~q_4. Therefore, the answer is yes.