Consider the following premises. w -> r. r -> t_4. p_1 -> w. t_4 -> p_1. Can we infer p_1 -> r from them? If possible, name the inference rules being used at each step.
 From r -> t_4, t_4 -> p_1 we can infer r -> p_1 via transitivity. Finally, from p_1 -> w, w -> r we can infer p_1 -> r via transitivity. Therefore, the answer is yes.