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 -> t_1. t_1 -> w. w <-> t_1.
w <-> t_1 can be inferred via the biconditional introduction rule. t_1 <-> w can be inferred via the biconditional introduction rule. w -> t_1 can be inferred via the biconditional elimination rule. t_1 -> w can be inferred via the biconditional elimination rule.