EN
In the space $Λ^p$ of polynomial p-forms in ℝⁿ we introduce some special inner product. Let $H^p$ be the space of polynomial p-forms which are both closed and co-closed. We prove in a purely algebraic way that $Λ^p$ splits as the direct sum $d*(Λ^{p+1}) ⊕ δ*(Λ^{p-1}) ⊕ H^p$, where d* (resp. δ*) denotes the adjoint operator to d (resp. δ) with respect to that inner product.