Consider the following premises. r -> q_6. t -> s_3. s -> t. q_6 -> s. Can we infer r -> s_3 from them?
 From r -> q_6, q_6 -> s we can infer r -> s. From s -> t, t -> s_3 we can infer s -> s_3. Finally, from r -> s, s -> s_3 we can infer r -> s_3. Therefore, the answer is yes.