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