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