Now showing items 36-55 of 70

• #### The Nash Problem from a Geometric and Topological Perspective ﻿

(2018-04-17)
We survey the proof of the Nash conjecture for surfaces and show how geometric and topological ideas developed in previous articles by the au- thors influenced it. Later we summarize the main ideas in the higher dimen- ...
• #### The Nash Problem from Geometric and Topological Perspective ﻿

(2020-03-01)
We survey the proof of the Nash conjecture for surfaces and show how geometric and topological ideas developed in previous articles by the authors influenced it. Later, we summarize the main ideas in the higher dimensional ...
• #### Némethi’s division algorithm for zeta-functions of plumbed 3-manifolds ﻿

(2018-08-27)
A polynomial counterpart of the Seiberg-Witten invariant associated with a negative definite plumbing 3-manifold has been proposed by earlier work of the authors. It is provided by a special decomposition of the zeta-function ...
• #### Neron models of intermediate Jacobians associated to moduli spaces ﻿

(2019-12-01)
Let $\pi_1:\mathcal{X} \to \Delta$ be a flat family of smooth, projective curves of genus $g \ge 2$, degenerating to an irreducible nodal curve $X_0$ with exactly one node. Fix an invertible sheaf $\mathcal{L}$ on $\mathcal{X}$ ...
• #### Non-normal affine monoids, modules and Poincaré series of plumbed 3-manifolds ﻿

(2017-05-18)
We construct a non-normal affine monoid together with its modules associated with a negative definite plumbed 3-manifold M. In terms of their structure, we describe the $H_1(M,\mathbb{Z})$-equivariant parts of the topological ...
• #### A note on the determinant map ﻿

(2017-01-10)
Classically, there exists a determinant map from the moduli space of semi-stable sheaves on a smooth, projective variety to the Picard scheme. Unfortunately, if the underlying variety is singular, then such a map does not ...
• #### On a conjecture of harris ﻿

(2019)
For d ≥ 4, the Noether-Lefschetz locus NLd parametrizes smooth, degree d sur- faces in P3 with Picard number at least 2. A conjecture of Harris states that there are only finitely many irreducible components of the ...
• #### On intersection cohomology with torus actions of complexity one ﻿

(2017-05-20)
The purpose of this article is to investigate the intersection cohomology for algebraic varieties with torus action. Given an algebraic torus T, one of our result determines the intersection cohomology Betti numbers of ...
• #### On Lipschitz rigidity of complex analytic sets ﻿

(2019-02-26)
We prove that any complex analytic set in $\mathbb{C}^n$ which is Lipschitz normally embedded at infinity and has tangent cone at infinity that is a linear subspace of $\mathbb{C}^n$ must be an affine linear subspace of ...
• #### On the generalized Nash problem for smooth germs and adjacencies of curve singularities ﻿

(2017-12-10)
In this paper we explore the generalized Nash problem for arcs on a germ of smooth surface: given two prime divisors above its special point, to determine whether the arc space of one of them is included in the arc space ...
• #### On the geometry of strongly flat semigroups and their generalizations ﻿

(2018-09-18)
Our goal is to convince the readers that the theory of complex normal surface singularities can be a powerful tool in the study of numerical semigroups, and, in the same time, a very rich source of interesting affine and ...
• #### On the length of perverse sheaves on hyperplane arrangements ﻿

(2019)
Abstract. In this article we address the length of perverse sheaves arising as direct images of rank one local systems on complements of hyperplane arrangements. In the case of a cone over an essential line arrangement ...
• #### On Zariski’s multiplicity problem at infinity ﻿

(2018-08-14)
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, ...
• #### Parametrization simple irreducible plane curve singularities in arbitrary characteristic ﻿

(2020-01-01)
We study the classification of plane curve singularities in arbitrary characteristic. We first give a bound for the determinacy of a plane curve singularity with respect to pararametrization equivalence in terms of its ...
• #### Perverse sheaves on semi-abelian varieties -- a survey of properties and applications ﻿

(2019-05)
We survey recent developments in the study of perverse sheaves on semi-abelian varieties. As concrete applications, we discuss various restrictions on the homotopy type of complex algebraic manifolds (expressed in terms ...
• #### A proof of the differentiable invariance of the multiplicity using spherical blowing-up ﻿

(2018-04-21)
In this paper we use some properties of spherical blowing-up to give an alternative and more geometric proof of Gau-Lipman Theorem about the differentiable invariance of the multiplicity of complex analytic sets. Moreover, ...
• #### A proof of the integral identity conjecture, II ﻿

(2017-10-31)
In this note, using Cluckers-Loeser’s theory of motivic integration, we prove the integral identity conjecture with framework a localized Grothendieck ring of varieties over an arbitrary base field of characteristic zero.
• #### Reflection maps ﻿

(2020)
Given a reflection group G acting on a complex vector space V , a reflection map is the composition of an embedding X → V with the quotient map V → Cp of G. We show how these maps, which can highly singular, may be studied ...
• #### Representation of surface homeomorphisms by tête-à-tête graphs ﻿

(2017-06-21)
We use tête-à-tête graphs as defined by N. A'campo and extended versions to codify all periodic mapping classes of an orientable surface with non-empty boundary, improving work of N. A'Campo and C. Graf. We also introduce ...
• #### Right unimodal and bimodal singularities in positive characteristic ﻿

(2017-08-07)
The problem of classification of real and complex singularities was initiated by Arnol'd in the sixties who classified simple, unimodal and bimodal singularities w.r.t. right equivalence. The classification of simple ...