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 <-> w_1. u <-> t. ~r_3 or u. r_3 or w_1.
w_1 or u can be inferred via the resolution rule. t -> w_1 can be inferred via the biconditional elimination rule. u -> t can be inferred via the biconditional elimination rule. w_1 -> t can be inferred via the biconditional elimination rule. t -> u can be inferred via the biconditional elimination rule.