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: t_2 -> w_3. w_3 -> t_2. w_3 -> t_2.
t_2 <-> w_3 can be inferred via the biconditional introduction rule. t_2 <-> w_3 can be inferred via the biconditional introduction rule. w_3 <-> t_2 can be inferred via the biconditional introduction rule. w_3 <-> t_2 can be inferred via the biconditional introduction rule.