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