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We consider flat families of reduced curves on a smooth surface S such that each member C has the same number of singularities of fixed singularity types and the corresponding (locally closed) subscheme H of the Hilbert scheme of S. We are…

alg-geom · Mathematics 2008-02-03 Gert-Martin Greuel , Christoph Lossen

In this work, we study families of singular surfaces in $\mathbb{C}^3$ parametrized by $\mathcal{A}$-finitely determined map germs. We consider the topological triviality and Whitney equisingularity of an unfolding $F$ of a finitely…

Complex Variables · Mathematics 2017-03-16 M. A. S. Ruas , O. N. Silva

We describe a natural decomposition of a normal complex surface singularity $(X,0)$ into its "thick" and "thin" parts. The former is essentially metrically conical, while the latter shrinks rapidly in thickness as it approaches the origin.…

Algebraic Geometry · Mathematics 2014-07-29 Lev Birbrair , Walter D Neumann , Anne Pichon

In the present article we work out a relative setup of generic structures on surface singularities. We fix an analytic type on a subgraph of a rational homology sphere resolution graph $\mathcal{T}$ and we choose a relatively generic normal…

Algebraic Geometry · Mathematics 2021-12-30 János Nagy

We begin the study of Lipschitz saturation for germs of toric singularities. By looking at their associated analytic algebras, we prove that if (X,0) is a germ of toric singularity with smooth normalization then its Lipschitz saturation is…

Algebraic Geometry · Mathematics 2024-07-30 Daniel Duarte , Arturo E. Giles Flores

In this article, we study the Lipschitz Geometry at infinity of complex analytic sets and we obtain results on algebraicity of analytic sets and on Bernstein's problem. Moser's Bernstein Theorem says that a minimal hypersurface which is a…

Complex Variables · Mathematics 2022-07-19 José Edson Sampaio

The germ of an algebraic variety is naturally equipped with two different metrics up to bilipschitz equivalence. The inner metric and the outer metric. One calls a germ of a variety Lipschitz normally embedded if the two metrics are…

Algebraic Geometry · Mathematics 2017-03-14 Dmitry Kerner , Helge Møller Pedersen , Maria A. S. Ruas

We produce examples of complex algebraic surfaces with isolated singularities such that these singularities are not metrically conic, i.e. the germs of the surfaces near singular points are not bi-Lipschitz equivalent, with respect to the…

Algebraic Geometry · Mathematics 2007-05-23 Lev Birbrair , Alexandre Fernandes

We look at topological equisingularity of a holomorphic family of reduced mapping germs f_t:(C^3,O)->C over a contractible base T having non-isolated singularities, by means of their normalisations. We introduce the notion of…

Algebraic Geometry · Mathematics 2007-05-23 Javier Fernandez de Bobadilla , Maria Pe Pereira

We study singularities of constant positive Gaussian curvature surfaces and determine the way they bifurcate in generic 1-parameter families of such surfaces. We construct the bifurcations explicitly using loop group methods. Constant…

Differential Geometry · Mathematics 2018-09-06 David Brander , Farid Tari

One of the main questions in the theory of normal surface singularities is to understand the relations between their geometry and topology. The lattice cohomology is an important tool in the study of topological properties of a plumbed…

Geometric Topology · Mathematics 2013-10-15 Tamás László

We study normal forms of germs of singular real-analytic Levi-flat hypersurfaces. We prove the existence of rigid normal forms for singular Levi-flat hypersurfaces which are defined by the vanishing of the real part of complex…

Complex Variables · Mathematics 2018-10-16 Arturo Fernández-Pérez , Gustavo Marra

Given a complex analytic germ $(X, 0)$ in $(\mathbb C^n, 0)$, the standard Hermitian metric of $\mathbb C^n$ induces a natural arc-length metric on $(X, 0)$, called the inner metric. We study the inner metric structure of the germ of an…

Algebraic Geometry · Mathematics 2022-04-20 André Belotto da Silva , Lorenzo Fantini , Anne Pichon

This article is concerned with the geometry of germs of real analytic surfaces in $(\mathbb{C}^2,0)$ having an isolated Cauchy-Riemann (CR) singularity at the origin. These are perturbations of {\it Bishop quadrics}. There are two kinds of…

Complex Variables · Mathematics 2022-03-29 Laurent Stolovitch , Zhiyan Zhao

In this paper, we prove metric analogues, in any dimension and in any co-dimension, of the famous Theorem of Mumford on smoothness of normal surfaces and the beautiful Theorem of Ramanujam that gives a topological characterization of…

Algebraic Geometry · Mathematics 2024-10-30 José Edson Sampaio

An explanation is given for the initially surprising ubiquity of separating sets in normal complex surface germs. It is shown that they are quite common in higher dimensions too. The relationship between separating sets and the geometry of…

Algebraic Geometry · Mathematics 2011-07-29 Lev Birbrair , Alexandre Fernandes , Walter D Neumann

We study invariance of multiplicity of complex analytic germs and degree of complex affine sets under outer bi-Lipschitz transformations (outer bi-Lipschitz homeomorphims of germs in the first case and outer bi-Lipschitz homeomorphims at…

Algebraic Geometry · Mathematics 2018-09-05 Javier Fernández de Bobadilla , Alexandre Fernandes , J. Edson Sampaio

For germs of subanalytic sets, we define two finite sequences of new numerical invariants. The first one is obtained by localizing the classical Lipschitz-Killing curvatures, the second one is the real analogue of the evanescent…

Differential Geometry · Mathematics 2011-11-15 Georges Comte , Michel Merle

The main result states that a connected conic singular sub-manifold of a Riemannian manifold, compact when the ambient manifold is non-Euclidean, is Lipschitz Normally Embedded: the outer and inner metric space structures are metrically…

Differential Geometry · Mathematics 2023-06-27 André Costa , Vincent Grandjean , Maria Michalska

For a germ $(X,0)$ of a normal complex analytic surface, let $E:=H^0({}^p_+IC_X\mathbb Z)_0$, where ${}^pIC_X\mathbb Z$ and ${}^p_+IC_X\mathbb Z$ denote the ordinary and dual middle-perversity intersection complexes with integral…

Algebraic Geometry · Mathematics 2026-04-27 Abdul Rahman