C-Bochner tensor Casorati curvature Darboux frame Euclidean submanifold Frenet frame Hessian manifolds Hessian sectional curvature Hodge–Laplacian Kähler–Einstein metrics L2-Stokes theorem L2-harmonic forms Minkowski plane Minkowskian angle Minkowskian length Minkowskian pseudo-angle Reeb flow symmetry Ricci curvature Ricci operator Ricci soliton Sasakian manifold Sasakian statistical manifold T-submanifolds affine hypersurface affine sphere anti-invariant capacity centrodes circular helices circular rectifying curves compact complex surfaces