What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? S_12(a_2) or ~R_12(a_2). forall x_12: R_12(x_12) <-> S_12(x_12).
R_12(a_2) -> S_12(a_2). forall x_12: R_12(x_12) -> S_12(x_12). forall x_12: S_12(x_12) -> R_12(x_12).