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We state and prove a generalization of the Poincar\'e-Hopf index theorem for manifolds with boundary. We then apply this result to non-vanishing complex vector fields.

Differential Geometry · Mathematics 2009-09-21 Benoît Jubin

A Poincar\'e-Hopf Theorem for line fields with point singularities on orientable surfaces can be found Hopf's 1956 Lecture Notes on Differential Geometry. In 1955 Markus presented such a theorem in all dimensions, but Markus' statement only…

Algebraic Topology · Mathematics 2017-04-26 Diarmuid Crowley , Mark Grant

The Poincar\'e-Hopf Theorem is a conservation law for real-analytic vector fields, which are tangential to a closed surface (such as a torus or a sphere). The theorem also governs real-analytic vector fields, which are tangential to…

Analysis of PDEs · Mathematics 2022-10-04 Aaron Pim

Let $M$ be a non-compact connected manifold with a cocompact and properly discontinuous action of a discrete group $G$. We establish a Poincar\'{e}-Hopf theorem for a bounded vector field on $M$ satisfying a mild condition on zeros. As an…

Geometric Topology · Mathematics 2024-12-18 Tsuyoshi Kato , Daisuke Kishimoto , Mitsunobu Tsutaya

The Poincare-Hopf Theorem is one of the most used in other areas of science. There are applications of the Poincare-Hopf Theorem in physics, chemistry, biology and even in economics, psychology, etc ... The Poincare-Hopf Theorem connects an…

History and Overview · Mathematics 2023-05-16 Jean-Paul Brasselet , Nguyen Thi Bich Thuy

The Poincar\'e-Hopf Theorem relates the Euler characteristic of a 2-dimensional compact manifold to the local behavior of smooth vector fields defined on it. However, despite the importance of Filippov vector fields, concerning both their…

Dynamical Systems · Mathematics 2024-09-18 Joyce A. Casimiro , Ricardo M. Martins , Douglas D. Novaes

For two complex vector bundles admitting a homomorphism with isolated singularities between them, we establish a Poincar\'e-Hopf type formula for the difference of the Chern character numbers of these two vector bundles. As a consequence,…

Geometric Topology · Mathematics 2010-06-14 Huitao Feng , Weiping Li , Weiping Zhang

A generalization of the Poincar\'{e}-Hopf index theorem applicable to hybrid dynamical systems is obtained. For the hybrid systems considered, guard sets are not assumed to be smooth; distinct "modes" are not assumed to have constant…

Dynamical Systems · Mathematics 2024-10-28 Matthew D. Kvalheim

Indices of singular points of a vector field or of a 1-form on a smooth manifold are closely related with the Euler characteristic through the classical Poincar\'e--Hopf theorem. Generalized Euler characteristics (additive topological…

Geometric Topology · Mathematics 2019-03-19 S. M. Gusein-Zade

For two complex vector bundles admitting a homomorphism between them, a Poincar\'e-Hopf formula for the difference of the Chern character numbers of these two vector bundles with isolated singularities is established by Huitao Feng, Weiping…

Differential Geometry · Mathematics 2022-10-18 Xu Chen

We compute (algebraically) the Euler characteristic of a complex of sheaves with constructible cohomology. A stratified Poincar\'e-Hopf formula is then a consequence of the smooth Poincar\'e-Hopf theorem and of additivity of the…

Algebraic Topology · Mathematics 2009-05-29 Stéphane Simon

The goal of this work is to generalize the Gauss-Bonnet and Poincar\'{e}-Hopf Theorems to the case of orbifolds with boundary. We present two such generalizations, the first in the spirit of Satake. In this case, the local data (i.e.…

Differential Geometry · Mathematics 2008-06-09 Christopher Seaton

Let $X \subset\mathbb{P}^r$ be a projective $d$-variety with isolated determinantal singularities and $\omega$ be a $1$-form on $X$ with a finite number of singularities (in the stratified sense). Under some technical conditions on $r$ we…

Geometric Topology · Mathematics 2026-04-17 N. G. Grulha , M. S. Pereira , H. Santana

Braid Floer homology is an invariant of proper relative braid classes. Closed integral curves of 1-periodic Hamiltonian vector fields on the 2-disc may be regarded as braids. If the Braid Floer homology of associated proper relative braid…

Symplectic Geometry · Mathematics 2012-04-04 Simone Munaò , Rob Vandervorst

Let $X$ be a projective algebraic $d$-variety endowed with isolated determinantal singularities, and let $\omega$ be a $1$-form on $X$ exhibiting a finite number of singularities (in the stratified sense). Under some technical conditions,…

Geometric Topology · Mathematics 2026-05-08 N. G. Grulha , M. S. Pereira , H. Santana

We introduce the index i(v) = 1 - X(S(v)) for critical points of a locally injective function f on the vertex set V of a simple graph G=(V,E). Here S(v) = {w in E | (v,w) in E, f(w)-f(v)<0} is the subgraph of the unit sphere at v in G. It…

Differential Geometry · Mathematics 2012-01-06 Oliver Knill

Poincar\'e's Polyhedron Theorem is a widely known valuable tool in constructing manifolds endowed with a prescribed geometric structure. It is one of the few criteria providing discreteness of groups of isometries. This work contains a…

Geometric Topology · Mathematics 2011-08-01 Sasha Anan'in , Carlos H. Grossi

In this paper we study the relationship of the Brouwer degree of a vector field with the dynamics of the induced flow. Analogous relations are studied for the index of a vector field. We obtain new forms of the Poincar% \'{e}-Hopf theorem…

Dynamical Systems · Mathematics 2024-01-17 Héctor Barge , José M. R. Sanjurjo

In this paper, we employ the framework of localization algebras to compute the equivariant K-homology class of the Euler characteristic operator, a central object in studying equivariant index theory on manifolds. This approach provides a…

Algebraic Topology · Mathematics 2024-10-22 Hongzhi Liu , Hang Wang , Zijing Wang , Shaocong Xiang

For a manifold with boundary, the restriction of Chern's transgression form of the Euler curvature form over the boundary is closed. Its cohomology class is called the secondary Chern-Euler class and used by Sha to formulate a relative…

Differential Geometry · Mathematics 2010-02-08 Zhaohu Nie
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