Consider the following premises. r -> q_4. r or ~q_4. ~u. u <-> r. Can we infer q_4 from them?
 From u <-> r, ~u we can infer ~r. From r or ~q_4 we can infer q_4 -> r. From r -> q_4, q_4 -> r we can infer r <-> q_4. Finally, from r <-> q_4, ~r we can infer ~q_4, which contradicts q_4. Therefore, the answer is no.