Consider the following premises. q_6 -> w_4. u <-> w_4. u_2 -> q_6. u_2 or u. Can we infer w_4 from them?
 From u_2 -> q_6, q_6 -> w_4 we can infer u_2 -> w_4. From u <-> w_4 we can infer u -> w_4. Finally, from u_2 -> w_4, u -> w_4, u_2 or u we can infer w_4. Therefore, the answer is yes.