The Gauss-Bonnet Theorem for coherent tangent bundles over surfaces with boundary and its applications

TL;DR

This paper extends the Gauss-Bonnet theorem to coherent tangent bundles over surfaces with boundary and explores its applications to surface maps, wave fronts, and geometric properties.

Contribution

It establishes a new Gauss-Bonnet formula for surfaces with boundary and applies it to analyze global surface properties and affine wave front geometries.

Findings

Gauss-Bonnet theorem for surfaces with boundary proved

Relation between boundary geodesic curvature and wave front singular curvature

Link between width functions of planar rosettes and curvature integrals

Abstract

In [31,32,33] the Gauss-Bonnet formulas for coherent tangent bundles over compact oriented surfaces (without boundary) were proved. We establish the Gauss-Bonnet theorem for coherent tangent bundles over compact oriented surfaces with boundary. We apply this theorem to investigate global properties of maps between surfaces with boundary. As a corollary of our results we obtain Fukuda-Ishikawa's theorem. We also study geometry of the affine extended wave fronts for planar closed non singular hedgehogs (rosettes). In particular, we find a link between the total geodesic curvature on the boundary and the total singular curvature of the affine extended wave front, which leads to a relation of integrals of functions of the width of a resette.