Consider the following premises. u_4 <-> q_3. t -> q_3. t. Can we infer ~u_4 from them?
 From u_4 <-> q_3 we can infer q_3 -> u_4. From t -> q_3, t we can infer q_3. Finally, from q_3 -> u_4, q_3 we can infer u_4, which contradicts ~u_4. Therefore, the answer is no.