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