Consider the following premises. p -> q_7. s_2 or ~q_7. s_2 -> p. Can we infer s_2 <-> p from them? If possible, name the inference rules being used at each step.
 From s_2 or ~q_7 we can infer q_7 -> s_2 via rewriting. From p -> q_7, q_7 -> s_2 we can infer p -> s_2 via transitivity. Finally, from s_2 -> p, p -> s_2 we can infer s_2 <-> p via biconditional introduction. Therefore, the answer is yes.