Consider the following premises. t -> q_3. u <-> q_3. u_2 <-> u. ~u_2. Can we infer ~t from them?
 From u_2 <-> u, ~u_2 we can infer ~u. From u <-> q_3, ~u we can infer ~q_3. Finally, from t -> q_3, ~q_3 we can infer ~t. Therefore, the answer is yes.