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: r -> ~q_12. q_12. p_6 -> r_6. t -> r_6. p_6 or t.
~r can be inferred via the modus tollens rule. r_6 can be inferred via the disjunction elimination rule.