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We classify isolated hypersurface singularities $f\in K[[x_1,..., x_n]]$, $K$ an algebraically closed field of characteristic $p>0$, which are simple w.r.t. right equivalence, that is, which have no moduli up to analytic coordinate change.…

Algebraic Geometry · Mathematics 2016-04-05 Gert-Martin Greuel , Nguyen Hong Duc

We give an overview of the fundamental definitions and results concerning hypersurface singularities, defined by convergent power series over an arbitrary real valued field. This approach combines, on the one hand, the classical case of…

Algebraic Geometry · Mathematics 2026-02-18 Gert-Martin Greuel

The paper is motivated on the open problem of resolution of singularities in positive characteristic. The aim is to present a form of induction which is different from that used by Hironaka. In characteristic zero induction is formulated by…

Algebraic Geometry · Mathematics 2010-12-24 Orlando Villamayor

In (Arnold, 1985), V.I. Arnold has obtained normal forms and has developed a classifier for, in particular, all isolated hypersurface singularities over the complex numbers up to modality 2. Building on a series of 105 theorems, this…

Algebraic Geometry · Mathematics 2019-08-15 Janko Boehm , Magdaleen S. Marais , Gerhard Pfister

We give a criterion to test geometric properties such as Whitney equisingularity and Thom's $a_f$ condition for new families of (possibly non-isolated) hypersurface singularities that "behave well" with respect to their Newton diagrams. As…

Algebraic Geometry · Mathematics 2020-05-05 Christophe Eyral , Mutsuo Oka

The Milnor number of an isolated hypersurface singularity, defined as the codimension $\mu(f)$ of the ideal generated by the partial derivatives of a power series $f$ whose zeros represent locally the hypersurface, is an important…

Algebraic Geometry · Mathematics 2023-08-15 Abramo Hefez , João Helder Olmedo Rodrigues , Rodrigo Salomão

This is the abstract prepared for Workshop on Topology and Geometry (Zhang jiang, China, October 1994), and is a review of my recent works. What kinds of combinations of singularities can appear in small deformation fibers of a fixed…

alg-geom · Mathematics 2008-02-03 Tohsuke Urabe

We study singularities f in K[[x_1,...,x_n]] over an algebraically closed field K of arbitrary characteristic with respect to right respectively contact equivalence, and we establish that the finiteness of the Milnor respectively the…

Algebraic Geometry · Mathematics 2012-03-27 Yousra Boubakri , Gert-Martin Greuel , Thomas Markwig

Suppose that $f$ defines a singular, complex affine hypersurface. If the critical locus of $f$ is one-dimensional at the origin, we obtain new general bounds on the ranks of the homology groups of the Milnor fiber, $F_{f, \mathbf 0}$, of…

Algebraic Geometry · Mathematics 2007-05-23 Lê Dũng Tráng , David B. Massey

Over $\C$, Henry Laufer classified all taut surface singularities. We adapt and extent his transcendental methods to positive characteristic. With this we show that if a normal surface singularity is taut over $\C$, then the normal surface…

Algebraic Geometry · Mathematics 2013-03-26 Felix Schüller

In his groundbreaking work on classification of singularities with regard to right and stable equivalence of germs, Arnold has listed normal forms for all isolated hypersurface singularities over the complex numbers with either modality…

Algebraic Geometry · Mathematics 2020-10-21 Janko Boehm , Magdaleen S. Marais , Gerhard Pfister

The aim of this article is the classification of simple 0-dimensional isolated complete intersection singularities in positive characteristic. As usual, a singularity is called simple or 0-modal if there are only finitely many isomorphism…

Algebraic Geometry · Mathematics 2025-07-24 Thuy Huong Pham , Gerhard Pfister , Gert-Martin Greuel

We present a classification algorithm for isolated hypersurface singularities of corank 2 and modality 1 over the real numbers. For a singularity given by a polynomial over the rationals, the algorithm determines its right equivalence class…

Algebraic Geometry · Mathematics 2020-10-16 Janko Boehm , Magdaleen S. Marais , Andreas Steenpass

The problem of classification of real and complex singularities was initiated by Arnol'd in the sixties who classified simple, unimodal and bimodal w.r.t. right equivalence. The classification of right simple singularities in positive…

Algebraic Geometry · Mathematics 2015-07-14 Hong Duc Nguyen

We provide normal forms for singularities of analytic hypersurfaces in $({\mathbb C}^n,0)$, using holomorphic vector fields.

Complex Variables · Mathematics 2023-01-06 Pedro Fortuny Ayuso

We prove the existence of normal forms for some local real-analytic Levi-flat hypersurfaces with an isolated line singularity. We also give sufficient conditions for that a Levi-flat hypersurface with a complex line as singularity to be a…

Complex Variables · Mathematics 2015-06-15 Arturo Fernández-Pérez

Assume that there exists a hypersurface singularity which cannot be resolved by iterated monoidal transformations in positive characteristic. We show that in the set of defining functions of hypersurface singularities which cannot be…

Algebraic Geometry · Mathematics 2010-06-21 Tohsuke Urabe

In this survey paper we give an overview on some aspects of singularities of algebraic varieties over an algebraically closed field of arbitrary characteristic. We review in particular results on equisingularity of plane curve…

Algebraic Geometry · Mathematics 2017-11-10 Gert-Martin Greuel

In this paper, we discuss the recognition problem for A_k-type singularities on wave fronts. We give computable and simple criteria of these singularities, which will play a fundamental role in generalizing the authors' previous work "the…

Differential Geometry · Mathematics 2015-05-13 Kentaro Saji , Masaaki Umehara , Kotaro Yamada

In the classification of real singularities by Arnold et al. (1985), normal forms, as representatives of equivalence classes under right equivalence, are not always uniquely determined. We describe the complete structure of the equivalence…

Algebraic Geometry · Mathematics 2016-01-18 Magdaleen S. Marais , Andreas Steenpass
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