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: r_2 -> w_2. ~t. r_2 -> t. w_2 -> r_2.
~r_2 can be inferred via the modus tollens rule. w_2 -> t can be inferred via the transitivity rule. r_2 <-> w_2 can be inferred via the biconditional introduction rule. w_2 <-> r_2 can be inferred via the biconditional introduction rule.