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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

We define two types of local indices of a vector field at an isolated zero on the boundary, and prove Poincare-Hopf-type index theorems for certain vector fields on a compact smooth manifold which have only isolated zeros.

Geometric Topology · Mathematics 2008-03-20 Hiroaki Kamae , Masayuki Yamasaki

We discuss different generalizations of the classical notion of the index of a singular point of a vector field to the case of vector fields or 1-forms on singular varieties, describe relations between them and formulae for their…

Algebraic Geometry · Mathematics 2007-05-23 Wolfgang Ebeling , Sabir M. Gusein-Zade

We consider manifolds with isolated singularities, i.e., topological spaces which are manifolds (say, $C^\infty$--) outside discrete subsets (sets of singular points). For (germs of) manifolds with, so called, cone--like singularities, a…

alg-geom · Mathematics 2007-05-23 Wolfgang Ebeling , Sabir M. Gusein-Zade

In this expository article, we study and discuss invariants of vector fields and holomorphic foliations that intertwine the theories of complex analytic singular varieties and singular holomorphic foliations on complex manifolds: two…

Complex Variables · Mathematics 2025-01-16 Maurício Corrêa , José Seade

We discuss the notions of indices of vector fields and 1-forms and their generalizations to singular varieties and varieties with actions of finite groups, as well as indices of collections of vector fields and 1-forms.

Algebraic Geometry · Mathematics 2021-07-06 Wolfgang Ebeling , Sabir M. Gusein-Zade

Equivariant versions of the radial index and of the GSV-index of a vector field or a 1-form on a singular variety with an action of a finite group are defined. They have values in the Burnside ring of the group. Poincar\'e-Hopf type…

Algebraic Geometry · Mathematics 2013-07-09 Wolfgang Ebeling , Sabir M. Gusein-Zade

This article is about 1-forms on complex analytic varieties and it is particularly relevant when the variety has non-isolated singularities. We first show how the radial extension technique of M.-H. Schwartz can be adapted to 1-forms,…

Algebraic Geometry · Mathematics 2007-05-23 J. -P. Brasselet , J. Seade , T. Suwa

Theorems on the existence of vector fields with given sets of Indexes of isolated Singular points are proved for the cases of closed manifolds, pairs of manifolds, manifolds with boundary, and gradient fields. It is proved that, on a…

Dynamical Systems · Mathematics 2007-05-23 A. O. Prishlyak

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

Homological index of a holomorphic 1-form on a complex analytic variety with an isolated singular point is an analogue of the usual index of a 1-form on a non-singular manifold. One can say that it corresponds to the top Chern number of a…

Algebraic Geometry · Mathematics 2018-07-03 Eugene Gorsky , Sabir M. Gusein-Zade

There are some generalizations of the classical Eisenbud-Levine-Khimshashvili formula for the index of a singular point of an analytic vector field on $R^n$ for vector fields on singular varieties. We offer an alternative approach based on…

Algebraic Geometry · Mathematics 2016-09-07 Wolfgang Ebeling , Sabir M. Gusein-Zade

G\'omez-Mont, Seade and Verjovsky introduced an index, now called GSV-index, generalizing the Poincar\'e-Hopf index to complex vector fields tangent to singular hypersurfaces. The GSV-index extends to the real case. This is a survey paper…

Dynamical Systems · Mathematics 2013-01-10 Pavao Mardesic

A Poincar\'{e}-Hopf theorem in the spirit of Pugh is proven for compact orbifolds with boundary. The theorem relates the index sum of a smooth vector field in generic contact with the boundary orbifold to the Euler-Satake characteristic of…

Differential Geometry · Mathematics 2009-04-06 Elliot Paquette , Christopher Seaton

If (V,0) is an isolated complete intersection singularity and X a holomorphic vector field tangent to V one can define an index of X, the so called GSV index, which generalizes the Poincare-Hopf index. We prove that the GSV index coincides…

Algebraic Geometry · Mathematics 2007-05-23 Oliver Klehn

If two G-manifolds are G-cobordant then characteristic numbers corresponding to the fixed point sets (submanifolds) of subgroups of G and to normal bundles to these sets coincide. We construct two analogues of these characteristic numbers…

Algebraic Geometry · Mathematics 2014-06-18 Wolfgang Ebeling , Sabir M. Gusein-Zade

We define an index of a collection of 1-forms on a complex isolated complete intersection singularity corresponding to a Chern number and, in the case when the 1-forms are complex analytic, express it as the dimension of a certain algebra.

Algebraic Geometry · Mathematics 2007-05-23 Wolfgang Ebeling , Sabir M. Gusein-Zade

We study holomorphic vector fields on isolated hypersurface singularities and derive global obstructions to the existence of holomorphic vector fields on compact singular varieties. For a hypersurface germ $(V,0)$ with an isolated…

Algebraic Geometry · Mathematics 2026-05-12 Diogo da Silva Machado , Jose Seade

For a G-invariant holomorphic 1-form with an isolated singular point on a germ of a complex-analytic G-variety with an isolated singular point (G is a finite group) one has notions of the equivariant homological index and of the (reduced)…

Algebraic Geometry · Mathematics 2017-01-10 Sabir M. Gusein-Zade , Firuza I. Mamedova

Integrals of the Pfaffian form over the nonsingular part of a projective variety compute information closely related to the Mather-Chern class of the variety and to other invariants such as the local Euler obstruction along strata of its…

Algebraic Geometry · Mathematics 2021-02-03 Paolo Aluffi , Mark Goresky
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