Consider the following premises. u -> s_4. ~w_3. ~u -> q. s_4 <-> w_3. Can we infer ~q from them?
 From s_4 <-> w_3, ~w_3 we can infer ~s_4. From u -> s_4, ~s_4 we can infer ~u. Finally, from ~u -> q, ~u we can infer q, which contradicts ~q. Therefore, the answer is no.