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_2. t_1 -> t. r_4. ~t_2.
~t can be inferred via the modus tollens rule. t_1 -> t_2 can be inferred via the transitivity rule. r_4 and ~t_2 can be inferred via the conjunction rule. ~t_2 and r_4 can be inferred via the conjunction rule.