What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? exists y: S(y) <-> P(y). forall y: U_1(y) -> P(y). forall y: P(y) -> U_1(y).
forall y: U_1(y) <-> P(y). forall y: P(y) <-> U_1(y). exists y: S(y) -> P(y). exists y: P(y) -> S(y).