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