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 -> q_6. q_6 -> t_4. t_4 -> r_2. q -> s. ~r_2.
~t_4 can be inferred via the modus tollens rule. s -> t_4 can be inferred via the transitivity rule. q_6 -> r_2 can be inferred via the transitivity rule. q -> q_6 can be inferred via the transitivity rule.