What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? ~p_21 or r_21. R_19(a_19) <-> q_2. forall x_19: ~R_19(x_19). p_21 or q_2.
q_2 or r_21. R_19(a_19) -> q_2. q_2 -> R_19(a_19).