Consider the following premises. ~w_2. t -> w_2. s_1 <-> q. s_1 -> t. Can we infer q from them?
 From t -> w_2, ~w_2 we can infer ~t. From s_1 -> t, ~t we can infer ~s_1. Finally, from s_1 <-> q, ~s_1 we can infer ~q, which contradicts q. Therefore, the answer is no.