Consider the following premises. p_7 -> r_1. r_1 -> t. p_7 or ~t. Can we infer ~(t <-> r_1) from them?
 From p_7 or ~t we can infer t -> p_7. From t -> p_7, p_7 -> r_1 we can infer t -> r_1. Finally, from t -> r_1, r_1 -> t we can infer t <-> r_1, which contradicts ~(t <-> r_1). Therefore, the answer is no.