EN
Let Mⁿ be a hypersurface in $R^{n+1}$. We prove that two classical Jacobi curvature operators $J_x$ and $J_y$ commute on Mⁿ, n > 2, for all orthonormal pairs (x,y) and for all points p ∈ M if and only if Mⁿ is a space of constant sectional curvature. Also we consider all hypersurfaces with n ≥ 4 satisfying the commutation relation $(K_{x,y} ∘ K_{z,u})(u) = (K_{z,u} ∘ K_{x,y})(u)$, where $K_{x,y}(u) = R(x,y,u)$, for all orthonormal tangent vectors x,y,z,w and for all points p ∈ M.