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_3 -> s. ~r_3. s -> u_3. t_3 -> r_3.
~t_3 can be inferred via the modus tollens rule. ~t_3 -> u_3 can be inferred via the transitivity rule.