Consider the following premises. p_6 -> q_6. q_6 -> p. p_6 or ~p. Can we infer p_6 <-> p from them?
 From p_6 -> q_6, q_6 -> p we can infer p_6 -> p. From p_6 or ~p we can infer p -> p_6. Finally, from p_6 -> p, p -> p_6 we can infer p_6 <-> p. Therefore, the answer is yes.