Consider the following premises. r_4 -> r_3. r_3 -> r_4. t -> r_4. p_2 <-> r_3. Can we infer t -> p_2 from them?
 From r_4 -> r_3, r_3 -> r_4 we can infer r_4 <-> r_3. From r_4 <-> r_3 we can infer r_4 -> r_3. From p_2 <-> r_3 we can infer r_3 -> p_2. From r_4 -> r_3, r_3 -> p_2 we can infer r_4 -> p_2. Finally, from t -> r_4, r_4 -> p_2 we can infer t -> p_2. Therefore, the answer is yes.