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_4 -> t. w_4 -> t. t -> w_4.
w_4 <-> t can be inferred via the biconditional introduction rule. w_4 <-> t can be inferred via the biconditional introduction rule. t <-> w_4 can be inferred via the biconditional introduction rule. t <-> w_4 can be inferred via the biconditional introduction rule.