Consider the following premises. p_15 -> p_17. w. p_17 -> p_15. p_17. Can we infer p_15 from them? If possible, name the inference rules being used at each step.
 From p_17, w we can infer p_17 and w via conjunction. From p_15 -> p_17, p_17 -> p_15 we can infer p_15 <-> p_17 via biconditional introduction. From p_17 and w we can infer p_17 via simplification. From p_15 <-> p_17 we can infer p_17 -> p_15 via biconditional elimination. Finally, from p_17 -> p_15, p_17 we can infer p_15 via modus ponens. Therefore, the answer is yes.