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: ~s. s <-> w_1. t <-> w_1. w <-> t.
s -> w_1 can be inferred via the biconditional elimination rule. t -> w_1 can be inferred via the biconditional elimination rule. w -> t can be inferred via the biconditional elimination rule. w_1 -> s can be inferred via the biconditional elimination rule. w_1 -> t can be inferred via the biconditional elimination rule. t -> w can be inferred via the biconditional elimination rule. ~w_1 can be inferred via the biconditional elimination rule.