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