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 -> w. ~w. r <-> q_3. w -> r.
~r can be inferred via the modus tollens rule. r <-> w can be inferred via the biconditional introduction rule. w <-> r can be inferred via the biconditional introduction rule. r -> q_3 can be inferred via the biconditional elimination rule. q_3 -> r can be inferred via the biconditional elimination rule.