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We introduce the notion of the Bruce-Roberts Tjurina number for holomorphic 1-forms relative to a pair $(X,V)$ of complex analytic subvarieties. When the pair $(X,V)$ consists of isolated complex analytic hypersurfaces, we prove that the…

Complex Variables · Mathematics 2024-10-01 Pedro Barbosa , Arturo Fernández-Pérez , Víctor León

We relate the Bruce-Roberts numbers of a 1-form with respect to an ICIS to other invariants as the GSV-index, Tjurina and Milnor numbers.

In this note we give a simple proof of the following relative analog of the well known Milnor-Palamodov theorem: the Bruce-Roberts number of a function relative to an isolated hypersurface singularity is equal to its topological Milnor…

Algebraic Geometry · Mathematics 2018-11-20 Konstantinos Kourliouros

Given a germ of an analytic variety $X$ and a germ of a holomorphic function $f$ with a stratified isolated singularity with respect to the logarithmic stratification of $X$, we show that under certain conditions on the singularity type of…

Complex Variables · Mathematics 2022-12-06 Carles Bivià-Ausina , Konstantinos Kourliouros , Maria Aparecida Soares Ruas

Let $(X,0)$ be an isolated hypersurface singularity defined by $\phi\colon(\mathbb C^n,0)\to(\mathbb C,0)$ and $f\colon(\mathbb C^n,0)\to\mathbb C$ such that the Bruce-Roberts number $\mu_{BR}(f,X)$ is finite. We first prove that…

We introduce a notion of a homological index of a holomorphic 1-form on a germ of a complex analytic variety with an isolated singularity, inspired by X. G\'omez-Mont and G.-M. Greuel. For isolated complete intersection singularities it…

Algebraic Geometry · Mathematics 2007-05-23 W. Ebeling , S. M. Gusein-Zade , J. Seade

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

This work investigates invariants, including the GSV-index, the local Euler obstruction, and the Brasselet number, within the context of isolated complete intersection singularities (ICIS). The goal is to forge connections among these…

Algebraic Geometry · Mathematics 2024-09-06 Raphael de Omena

We collect some classical results about holomorphic 1-forms of a reduced complex curve singularity, in particular of a complete intersection, and use them to compare the Milnor number, the Tjurina number and the dimension of the torsion…

Algebraic Geometry · Mathematics 2017-09-12 Gert-Martin Greuel

We collect some classical results about holomorphic 1-forms of a reduced complex curve singularity. They are used to study the pull-back of holomorphic 1-forms on an isolated complete intersection curve singularity under the normalization…

Algebraic Geometry · Mathematics 2019-09-17 Alexandru Dimca , Gert-Martin Greuel

We extend the notion of $\mu^*$-sequence and Tjurina number of functions to the framework of Bruce-Roberts numbers, that is, to pairs formed by the germ at $0$ of a complex analytic variety $X\subseteq \mathbb C^n$ and a finitely $\mathcal…

Algebraic Geometry · Mathematics 2018-10-26 Carles Bivià-Ausina , María Aparecida Soares Ruas

Given a compact complex manifold $X$, we prove a Baum-Bott type formula for one-dimensional holomorphic foliations on $X$ that are logarithmic along a hypersurface with isolated singularities. We show that the residues of these foliations…

Algebraic Geometry · Mathematics 2025-03-26 Diogo Da Silva Machado

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

We give formulas for the Bruce-Roberts number $\mu_{BR}(f,X)$ and its relative version $\mu_{BR}^{-}(f,X)$ of a function $f$ with respect to an ICIS $(X,0)$. We show that $\mu_{BR}^{-}(f,X)=\mu(f^{-1}(0)\cap X,0)+\mu(X,0)-\tau(X,0)$, where…

We consider 1-forms on, so called, essentially isolated determinantal singularities (a natural generalization of isolated ones), show how to define analogues of the Poincar\'e--Hopf index for them, and describe relations between these…

Algebraic Geometry · Mathematics 2008-06-03 W. Ebeling , S. M. Gusein-Zade

For a complex analytic variety with an action of a finite group and for an invariant 1-form on it, we give an equivariant version (with values in the Burnside ring of the group) of the local Euler obstruction of the 1-form and describe its…

Algebraic Geometry · Mathematics 2014-07-25 Wolfgang Ebeling , Sabir M. Gusein-Zade

Based on work of R. Lazarsfeld and M. Popa, we use the derivative complex associated to the bundle of the holomorphic p-forms to provide inequalities for all the Hodge numbers of a special class of irregular compact Kaehler manifolds. For…

Algebraic Geometry · Mathematics 2012-04-06 Luigi Lombardi

We study codimension two determinantal varieties with isolated singularities. These singularities admit a unique smoothing, thus we can define their Milnor number as the middle Betti number of their generic fiber. For surfaces in C^4, we…

Algebraic Geometry · Mathematics 2011-11-29 Miriam da Silva Pereira , Maria Aparecida Soares Ruas

In this paper, we introduce the notions of the $k$-th Milnor number and the $k$-th Tjurina number for a germ of holomorphic foliation on the complex plane with an isolated singularity at the origin. We develop a detailed study of these…

Complex Variables · Mathematics 2025-11-11 Marcela Ribeiro , Arturo Fernández-Pérez

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
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