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) or Q_4(y). forall y: Q_13(y) <-> U(y). forall y: Q_13(y) -> Q_4(y). forall y: Q_4(y) -> Q_13(y).
forall y: Q_13(y) <-> Q_4(y). forall y: Q_4(y) <-> Q_13(y). forall y: Q_13(y) -> U(y). forall y: U(y) -> Q_13(y).