Consider the following premises. p_7 -> p_1. p_7 or ~q_7. p_1 -> q_7. Can we infer p_7 <-> p_1 from them? If possible, name the inference rules being used at each step.
 From p_7 or ~q_7 we can infer q_7 -> p_7 via rewriting. From p_1 -> q_7, q_7 -> p_7 we can infer p_1 -> p_7 via transitivity. Finally, from p_7 -> p_1, p_1 -> p_7 we can infer p_7 <-> p_1 via biconditional introduction. Therefore, the answer is yes.