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This article is devoted to studying multiplicity and regularity of real analytic sets. We present an equivalence for real analytic sets, named blow-spherical equivalence, which generalizes differential equivalence and subanalytic…

Algebraic Geometry · Mathematics 2021-05-21 José Edson Sampaio

We give partial answers to a metric version of Zariski's multiplicity conjecture. In particular, we prove the multiplicity of complex analytic surface (not necessarily isolated) singularities in $\mathbb{C}^3$ is a bi-Lipschitz invariant.

Algebraic Geometry · Mathematics 2017-05-17 Alexandre Fernandes , J. Edson Sampaio

We address a metric version of Zariski's multiplicity conjecture at infinity that says that two complex algebraic affine sets which are bi-Lipschitz homeomorphic at infinity must have the same degree. More specifically, we prove that the…

Algebraic Geometry · Mathematics 2019-01-01 J. Edson Sampaio

In this paper we study bilipschitz equivalences of germs of holomorphic foliations in $(\mathbb{C}^2,0)$. We prove that the algebraic multiplicity of a singularity is invariant by such equivalences. Moreover, for a large class of…

Dynamical Systems · Mathematics 2016-01-26 Rudy Rosas

The multiplicity of an algebraic curve $C$ in the complex plane at a point $p$ on that curve is defined as the number of points that occur at the intersection of $C$ with a general complex line that passes close to the point $p$. It is…

Algebraic Geometry · Mathematics 2022-12-22 Alexandre Fernandes , José Edson Sampaio

Let $X\subset \mathbb{C}^n; Y\subset \mathbb{C}^m$ be closed affine varieties and let $\phi: X\to Y$ be an algebraic bi-Lipschitz homeomorphism. Then ${\rm deg}\ X={\rm deg}\ Y.$ Similarly, let $(X,0)\subset (\mathbb{C}^n,0), (Y,0)\subset…

Algebraic Geometry · Mathematics 2021-05-07 Zbigniew Jelonek

We give conditions for topological and bi-Lipschitz equivalences within a class of mixed singularities of Pham-Brieskorn type. As a consequence, we construct infinite families that are topologically trivial but have distinct bi-Lipschitz…

Algebraic Geometry · Mathematics 2026-05-05 Inácio Rabelo

This paper is devoted to proving the differential invariance of the multiplicity of real and complex analytic sets. In particular, we prove the real version of Gau-Lipman's Theorem, i.e., it is proved that the multiplicity mod 2 of real…

Algebraic Geometry · Mathematics 2020-09-30 José Edson Sampaio

We prove that if two germs of irreducible complex analytic curves at $0\in\mathbb{C}^2$ have different sequence of characteristic exponents, then there exists $0<\alpha<1$ such that those germs are not $\alpha$-H\"older homeomorphic. For…

Algebraic Geometry · Mathematics 2017-04-11 Alexandre Fernandes , J. Edson Sampaio , Joserlan P. Silva

In this paper, we prove that two normal complex surface germs that are inner bilipschitz--but not necessarily orientation-preserving--homeomorphic, have in fact the same oriented topological type and the same minimal plumbing graph. Along…

Algebraic Geometry · Mathematics 2025-11-10 Lorenzo Fantini , Anne Pichon

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 compute Hoelder Complexes,i.e. the complete bi-Lipschitz invariants, for germs of real weighed homogeneous algebraic or semialgebraic surfaces.

Algebraic Geometry · Mathematics 2007-12-18 Lev Birbrair , Alexandre Fernandes

In this work, we consider a pair $(\textbf{X},0)$ and $(\textbf{Y},0)$ of hypersurfaces in $(\mathbb{C}^{n+1},0)$ parametrized by finitely determined, quasihomogeneous map germs $f$ and $g,$ respectively. Zariski asked whether the…

Algebraic Geometry · Mathematics 2025-11-11 Otoniel Nogueira da Silva , Manoel Messias da Silva Júnior

We prove that if there exists a bi-Lipschitz homeomorphism (not necessarily subanalytic) between two subanalytic sets, then their tangent cones are bi-Lipschitz homeomorphic. As a consequence of this result, we show that any Lipschitz…

Algebraic Geometry · Mathematics 2015-09-22 J. Edson Sampaio

We construct an invariant of the bi-Lipschitz contact equivalence of continuous function germs definable in a polynomially bounded o-minimal structure, such as semialgebraic functions. For a germ $f,$ the invariant is given in terms of the…

Algebraic Geometry · Mathematics 2019-01-16 Tien-Son Pham , Nguyen Thao Nguyen Bui

In this paper, we prove Fukui-Kurdyka-Paunescu's Conjecture, which says that subanalytic arc-analytic bi-Lipschitz homeomorphisms preserve the multiplicities of real analytic sets. We also prove several other results on the invariance of…

Algebraic Geometry · Mathematics 2021-08-18 Alexandre Fernandes , Zbigniew Jelonek , José Edson Sampaio

It was conjectured that multiplicity of a singularity is bi-Lipschitz invariant. We disprove this conjecture, constructing examples of bi-Lipschitz equivalent complex algebraic singularities with different values of multiplicity.

Algebraic Geometry · Mathematics 2021-09-20 Lev Birbrair , Alexandre Fernandes , J. Edson Sampaio , Misha Verbitsky

In this paper we study the bi-Lipschitz triviality of deformations of an analytic function germ $f$ defined on a germ of an analytic variety $(X, 0)$ in $\mathbb C^n$. We introduce the notion of strongly rational $\mathscr R_X$-bi-Lipschitz…

Algebraic Geometry · Mathematics 2025-02-11 Raúl Oset Sinha , Maria Aparecida Soares Ruas

We show that two bi-Lipschitz equivalent Brieskorn-Pham hypersurfaces have the same multiplicities at $0$. Moreover we show that if two algebraic $(n-1)$-dimensional cones $P, R\subset\mathbb C^n$ with isolated singularities are…

Algebraic Geometry · Mathematics 2024-04-11 Alexandre Fernandes , Zbigniew Jelonek , José Edson Sampaio

We provide sharp lower bounds for the multiplicity of a local holomorphic foliation defined in a complex surface in terms of data associated to a germ of invariant curve. Then we apply our methods to invariant curves whose branches are…

Complex Variables · Mathematics 2023-10-23 Pedro Fortuny Ayuso , Javier Ribón
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