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_19 -> r. r -> q_19. r_3 and q_14.
~q_19 can be inferred via the modus tollens rule. r_3 can be inferred via the simplification rule. q_14 can be inferred via the simplification rule. q_19 <-> r can be inferred via the biconditional introduction rule. r <-> q_19 can be inferred via the biconditional introduction rule.