Consider the following premises. u -> ~t_1. u <-> s_4. t_1. s_4. Can we infer q_1 from them?
 From u -> ~t_1, t_1 we can infer ~u. From u <-> s_4, ~u we can infer ~s_4. From ~s_4 we can infer ~s_4 or q_1. Finally, from ~s_4 or q_1, s_4 we can infer q_1. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.