Consider the following premises. s <-> p_1. s -> q_6. ~q_6. q_6 -> s. Can we infer p_1 from them?
 From s -> q_6, q_6 -> s we can infer s <-> q_6. From s <-> q_6, ~q_6 we can infer ~s. Finally, from s <-> p_1, ~s we can infer ~p_1, which contradicts p_1. Therefore, the answer is no.