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