Consider the following premises. t_3 <-> t_4. t_3. ~t_4. Can we infer q_1 from them?
 From t_3 <-> t_4, ~t_4 we can infer ~t_3. From t_3 we can infer t_3 or q_1. Finally, from t_3 or q_1, ~t_3 we can infer q_1. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.