Riemannian metric representatives of the Stiefel-Whitney classes
Abstract
If is a closed manifold, and is a smooth triangulation of , Whitney proved that all of the Stiefel-Whitney classes are specified as cochains on the dual cell complex assigning the value mod to each dual cell. We provide the pair with an arbitrary Riemannian metric , and use Whitney's criteria to show that there are associated representatives of all the Stiefel-Whitney classes . The representative of is determined by , the s computed in a frame that is locally defined at each dual -cell; the representatives of the even classes are determined by the Chern-Gauss-Bonnet density -form of locally defined totally geodesic oriented manifolds with boundary associated to each dual -cell; and the representatives of the odd classes are determined by the hypersurface area form of the boundary sphere of a locally defined totally geodesic oriented manifold with boundary associated to each dual -cell. If is Hermitian, we prove that the metric representative of so obtained is the reduction of the -th Chern class induced by the coefficient homomorphism, and that the metric representative of any odd degree class so obtained is trivial in cohomology.
Keywords
Cite
@article{arxiv.2004.05719,
title = {Riemannian metric representatives of the Stiefel-Whitney classes},
author = {Santiago R Simanca},
journal= {arXiv preprint arXiv:2004.05719},
year = {2026}
}
Comments
This version contains a number of editorial corrections to the original, and includes several changes prompted by comments of a referee that improve significantly the presentation