This follows by applying the dimension formula onto the Laplacian \(\Delta\colon \mathcal{P}_l\to \mathcal{P}_{l-2}\), since it is surjective.
This follows by applying the dimension formula onto the Laplacian \(\Delta\colon \mathcal{P}_l\to \mathcal{P}_{l-2}\), since it is surjective.