Consider the following premises. p_11 -> w_4. r_6 -> r_1. t -> r_1. p_11. w_4 -> r_6. Can we infer r_1 from them?
 From p_11 we can infer p_11 or t. From p_11 -> w_4, w_4 -> r_6 we can infer p_11 -> r_6. From p_11 -> r_6, r_6 -> r_1 we can infer p_11 -> r_1. Finally, from p_11 -> r_1, t -> r_1, p_11 or t we can infer r_1. Therefore, the answer is yes.