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). forall y: U_4(y) <-> S(y). exists y: U(y) <-> U_4(y).
forall y: U_4(y) -> S(y). exists y: U(y) -> U_4(y). forall y: S(y) -> U_4(y). exists y: U_4(y) -> U(y). exists y: ~U_4(y).