Consider the following premises. p_1 -> u_1. q -> p_1. s <-> u_1. Can we infer ~(q -> s) from them?
 From s <-> u_1 we can infer u_1 -> s. From p_1 -> u_1, u_1 -> s we can infer p_1 -> s. Finally, from q -> p_1, p_1 -> s we can infer q -> s, which contradicts ~(q -> s). Therefore, the answer is no.