Consider the following premises. t -> r_1. t or p_4. p_4 <-> r_1. p. Can we infer ~r_1 from them?
 From p_4 <-> r_1 we can infer p_4 -> r_1. Finally, from t -> r_1, p_4 -> r_1, t or p_4 we can infer r_1, which contradicts ~r_1. Therefore, the answer is no.