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