Consider the following premises. ~p_3. w <-> r. w <-> p_3. w_1. Can we infer r from them? If possible, name the inference rules being used at each step.
 From w <-> p_3, ~p_3 we can infer ~w via biconditional elimination. Finally, from w <-> r, ~w we can infer ~r via biconditional elimination, which contradicts r. Therefore, the answer is no.