Consider the following premises. p_1 <-> w. p_1 -> q_2. ~s_1. s_1 <-> q_2. Can we infer w from them?
 From s_1 <-> q_2, ~s_1 we can infer ~q_2. From p_1 -> q_2, ~q_2 we can infer ~p_1. Finally, from p_1 <-> w, ~p_1 we can infer ~w, which contradicts w. Therefore, the answer is no.