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