What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall y_4: R(y_4) <-> U(y_4). exists y_4: R(y_4) -> U(y_4).
forall y_4: R(y_4) -> U(y_4). forall y_4: U(y_4) -> R(y_4).