What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: ~w_1. w_1 -> p_1. p_1 -> w_1.
~p_1 can be inferred via the modus tollens rule. w_1 <-> p_1 can be inferred via the biconditional introduction rule. p_1 <-> w_1 can be inferred via the biconditional introduction rule.