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. t_1 or t_4. ~t_1 or r. u_3. t_4 <-> t.
~t and u_3 can be inferred via the conjunction rule. u_3 and ~t can be inferred via the conjunction rule. t_4 or r can be inferred via the resolution rule. t_4 -> t can be inferred via the biconditional elimination rule. t -> t_4 can be inferred via the biconditional elimination rule. ~t_4 can be inferred via the biconditional elimination rule.