Consider the following premises. r <-> u_2. r_4 -> r. w_3 or r_4. w_3 -> u_2. Can we infer r from them?
 From r <-> u_2 we can infer u_2 -> r. From w_3 -> u_2, u_2 -> r we can infer w_3 -> r. Finally, from w_3 -> r, r_4 -> r, w_3 or r_4 we can infer r. Therefore, the answer is yes.