Consider the following premises. s_4 <-> u_1. s <-> s_4. s <-> q. r <-> u_1. ~r. Can we infer q from them?
 From r <-> u_1, ~r we can infer ~u_1. From s_4 <-> u_1, ~u_1 we can infer ~s_4. From s <-> s_4, ~s_4 we can infer ~s. Finally, from s <-> q, ~s we can infer ~q, which contradicts q. Therefore, the answer is no.