What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? r. r -> u. p_19 -> q_19. r_3 <-> p_19. ~q_19.
u. ~p_19. r and ~q_19. ~q_19 and r. r_3 -> p_19. p_19 -> r_3.