What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall x: P_2(x) <-> P(x). forall x: S(x) -> P_2(x). forall x: ~P(x).
forall x: P_2(x) -> P(x). forall x: P(x) -> P_2(x). forall x: ~P_2(x).