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Isolated hypersurface singularities come equipped with distinguished bases of their Milnor lattices and with upper triangular integral matrices, which are called here distinguished matrices. These matrices form an orbit of a braid group and…

Algebraic Geometry · Mathematics 2026-03-03 Sven Balnojan , Claus Hertling

In this paper we use the results from the first part to compute the vanishing topology for matrix singularities based on certain spaces of matrices. We place the variety of singular matrices in a geometric configuration of free divisors…

Algebraic Geometry · Mathematics 2014-11-11 James Damon , Brian Pike

In this note, we give several equivalent characterizations of higher Du Bois and higher rational singularities in the context of globally defined hypersurfaces. As a key input, we characterize these singularities using the Hodge filtration…

Algebraic Geometry · Mathematics 2024-12-13 Laurenţiu Maxim , Ruijie Yang

We compare several different methods involving Hodge-theoretic spectra of singularities which produce constraints on the number and type of isolated singularities on projective hypersurfaces of fixed degree. In particular, we introduce a…

Algebraic Geometry · Mathematics 2024-02-01 B. Castor

Using invariants from commutative algebra to count geometric objects is a basic idea in singularities. For example, the multiplicity of an ideal is used to count points of intersection of two analytic sets at points of non-transverse…

Algebraic Geometry · Mathematics 2007-05-23 Terence Gaffney

We present algorithms to classify isolated hypersurface singularities over the real numbers according to the classification by V.I. Arnold (Arnold et al., 1985). This first part covers the splitting lemma and the simple singularities; a…

Algebraic Geometry · Mathematics 2016-01-15 Magdaleen S. Marais , Andreas Steenpass

We show that isolated surface singularities which are non-normal may have Milnor fibers which are non-diffeomorphic to those of their normalizations. Therefore, non-normal isolated singularities enrich the collection of Stein fillings of…

Algebraic Geometry · Mathematics 2015-03-06 Patrick Popescu-Pampu

For isolated complex hypersurface singularities with real defining equation we show the existence of a monodromy vector field such that complex conjugation intertwines the local monodromy diffeomorphism with its inverse. In particular, it…

Algebraic Geometry · Mathematics 2007-05-23 Norbert A'Campo

For plane curve singularities we construct a mixed Hodge structure (MHS) over the integers on the fundamental group of the Milnor fiber. The concept nearby fundamental group is introduced and we develop a theory of iterated integrals along…

Algebraic Geometry · Mathematics 2007-05-23 Rainer H. Kaenders

We enumerate complex algebraic hypersurfaces in $P^n$, of a given (high) degree with one singular point of a given singularity type. Our approach is to compute the (co)homology classes of the corresponding equi-singular strata in the…

Algebraic Geometry · Mathematics 2014-02-26 Dmitry Kerner

A cyclic quotient singularity of type $p^2/pq-1$ ($0<q<p, (p,q)=1$) has a smoothing whose Milnor fibre is a $\mathbb Q$HD, or rational homology disk (i.e., the Milnor number is $0$) ([9], 5.9.1). In the 1980's, we discovered additional…

Algebraic Geometry · Mathematics 2020-06-29 Jonathan Wahl

We give a different formulation for describing maximal surfaces in Lorentz-Minkowski space, $\mathbb{L}^3$, using the identification of $\mathbb L^3$ with $\mathbb C\times \mathbb R$. Further we give a different proof for the singular…

Differential Geometry · Mathematics 2017-03-16 Rukmini Dey , Pradip Kumar , Rahul Kumar Singh

The sandwiched surface singularities are those rational surface singularities which dominate birationally smooth surface singularities. de Jong and van Straten showed that one can reduce the study of the deformations of a sandwiched surface…

Algebraic Geometry · Mathematics 2012-12-27 Andras Nemethi , Patrick Popescu-Pampu

Let $V$ be a degree $d$, reduced hypersurface in $\mathbb{CP}^{n+1}$, $n \geq 1$, and fix a generic hyperplane, $H$. Denote by $\mathcal{U}$ the (affine) hypersurface complement, $\mathbb{CP}^{n+1}- V \cup H$, and let $\mathcal{U}^c$ be the…

Algebraic Topology · Mathematics 2012-04-03 Laurentiu Maxim

In this article we study Cohen-Macaulay modules over one-dimensional hypersurface singularities and the relationship with the representation theory of associative algebras using methods of cluster tilting theory. We give a criterion for…

Representation Theory · Mathematics 2010-11-01 Igor Burban , Osamu Iyama , Bernhard Keller , Idun Reiten

The main purpose of this article is to lay the foundations for a classification of isolated hypersurface singularities in positive characteristic. Although our article is in the spirit of Arnol'd who classified real an complex hypersurfaces…

Algebraic Geometry · Mathematics 2010-11-18 Yousra Boubakri , Gert-Martin Greuel , Thomas Markwig

We review properties of closed meromorphic $1$-forms and of the foliations defined by them. We present and explain classical results from foliation theory, like index theorems, the existence of separatrices, and resolution of singularities…

Complex Variables · Mathematics 2023-06-07 Jorge Vitório Pereira

All varieties, extremal contractions, singularities are divided on exceptional and non-exceptional ones. Roughly speaking, there are the infinite families of non-exceptional varieties, extremal contractions or singularities and only the…

Algebraic Geometry · Mathematics 2015-06-26 S. A. Kudryavtsev

We give a new formula for the Chern-Schwartz-MacPherson class of a hypersurface in a nonsigular compact complex analytic variety. In particular this formula generalizes our previous result on the Euler characteristic of such a hypersurface.…

Algebraic Geometry · Mathematics 2007-05-23 Adam Parusinski , Piotr Pragacz

We consider a hypersurface in $\mathbb{C}^n$ with an isolated singular point at the origin, and study the mixed Hodge structure of the stalk of its intersection cohomology complex at the origin. In particular we express the dimension of…

Algebraic Geometry · Mathematics 2017-02-13 Takahiro Saito