Consider the following premises. p_22 <-> r. ~q_22. q_2 and s. p_22 <-> q_22. Can we infer r from them? If possible, name the inference rules being used at each step.
 From p_22 <-> q_22, ~q_22 we can infer ~p_22 via biconditional elimination. Finally, from p_22 <-> r, ~p_22 we can infer ~r via biconditional elimination, which contradicts r. Therefore, the answer is no.