What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? T(f) -> t_4. t_4 <-> S(f). forall x: T(x) <-> S(x).
t_4 -> S(f). S(f) -> t_4. forall x: T(x) -> S(x). forall x: S(x) -> T(x).