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 or s. w -> w_3. ~w_3. w_1 <-> w.
~w can be inferred via the modus tollens rule. w_1 -> w can be inferred via the biconditional elimination rule. w -> w_1 can be inferred via the biconditional elimination rule.