Consider the following premises. q_6 -> t. p_6 -> q_6. p_6 or ~t. Can we infer ~(t <-> p_6) from them?
 From p_6 -> q_6, q_6 -> t we can infer p_6 -> t. From p_6 or ~t we can infer t -> p_6. Finally, from t -> p_6, p_6 -> t we can infer t <-> p_6, which contradicts ~(t <-> p_6). Therefore, the answer is no.