Quasisections of circle bundles and Euler class
Geometric Topology
2025-04-10 v2
Abstract
Let be an oriented circle bundle over an oriented closed surface . A quasisection is a smooth surface (either closed or bordered) mapped by a generic smooth mapping to such that . In the paper we derive a local formula for the Euler number, that is, we show that Euler number (Euler class) of the bundle equals the sum of weights of (some of) singularities of a quasisection.We also prove the uniqueness of such a formula. The local formula is a close relative of M. Kazarian's formula which relates the Euler number and Morse bifurcations of a generic function defined on the total space .
Cite
@article{arxiv.2410.22453,
title = {Quasisections of circle bundles and Euler class},
author = {Gaiane Panina and Timur Shamazov and Maksim Turevskii},
journal= {arXiv preprint arXiv:2410.22453},
year = {2025}
}