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We study a specific class of deformations of curve singularities: the case when the singular point splits to several ones, such that the total $\delta$ invariant is preserved. These are also known as equi-normalizable or equi-generic…

Algebraic Geometry · Mathematics 2010-01-18 Dmitry Kerner

We study threefolds of general type constructed as $\mathbb{Z}_2^s$-covers of weighted projective spaces with a particular focus on their invariants, deformation theory, and the behavior of the $m$-canonical map. For the invariants, we…

Algebraic Geometry · Mathematics 2026-05-08 Patricio Gallardo , Jayan Mukherjee

The braid monodromy factorization of the branch curve of a surface of general type is known to be an invariant that completely determines the diffeomorphism type of the surface. Calculating this factorization is of high technical…

Algebraic Geometry · Mathematics 2007-05-23 Michael Friedman , Mina Teicher

In this article, we give the classification of normal del Pezzo surfaces of rank one with at most log canonical singularities containing the affine plane defined over an algebraically non-closed field of characteristic zero. As an…

Algebraic Geometry · Mathematics 2023-03-24 Masatomo Sawahara

We investigate the behavior of semi-orthogonal decompositions of bounded derived categories of singular varieties under flat deformations to smooth varieties. We consider a Q-Gorenstein smoothing of a surface with a quotient singularity,…

Algebraic Geometry · Mathematics 2024-10-22 Yujiro Kawamata

We develop some basic facts on deformations of exterior differential ideals on a smooth complex algebraic variety. With these tools we study deformations of several types of differential ideals, leading to several irreducible components of…

Algebraic Geometry · Mathematics 2025-09-05 Fernando Cukierman , César Massri

We consider the space of embeddings of finitely many circles that bound disks in non-positively curved surfaces. We index the connected components of this space with finite rooted trees and show that the connected components are classifying…

Algebraic Topology · Mathematics 2026-01-21 Ryan C. Gelnett

We complement Catanese's results on isotrivially fibred surfaces by completely describing the components containing an isotrivial surface with monodromy group $\ZZ/2\ZZ$. We also give an example for deformation equivalent isotrivial…

Algebraic Geometry · Mathematics 2016-09-07 Martin Moeller

With the help of hyper-ideal circle pattern theory, we have developed a discrete version of the classical uniformization theorems for surfaces represented as finite branched covers over the Riemann sphere as well as compact polyhedral…

Metric Geometry · Mathematics 2017-08-25 Alexander Bobenko , Nikolay Dimitrov , Stefan Sechelmann

We consider the extrinsic geometry of surfaces in simply isotropic space, a three-dimensional space equipped with a rank 2 metric of index zero. Since the metric is degenerate, a surface normal cannot be unequivocally defined based on…

Differential Geometry · Mathematics 2020-11-13 Alev Kelleci , Luiz C. B. da Silva

One studies certain degenerations of the generic square matrix over a field $k$ along with its main related structures, such as the determinant of the matrix, the ideal generated by its partial derivatives, the polar map defined by these…

Commutative Algebra · Mathematics 2017-10-19 Rainelly Cunha , Zaqueu Ramos , Aron Simis

We give a slope equality for fibered surfaces whose general fiber is a smooth plane curve. As a corollary, we prove a "strong" Durfee-type inequality for isolated hypersurface surface singularities, which implies Durfee's strong conjecture…

Algebraic Geometry · Mathematics 2018-04-18 Makoto Enokizono

We address the inverse problem of recovering a degeneracy point within the diffusion coefficient of a one-dimensional complex parabolic equation by observing the normal derivative at one point of the boundary. The strongly degenerate case…

Analysis of PDEs · Mathematics 2026-05-13 Piermarco Cannarsa , Veronica Danesi , Anna Doubova

This article studies the possible degenerations of plane Cremona transformations of some degree into maps of smaller degree.

Algebraic Geometry · Mathematics 2015-09-30 Jérémy Blanc , Alberto Calabri

The notions of discrete conformality on triangle meshes have rich mathematical theories and wide applications. The related notions of discrete uniformizations on triangle meshes, suggest efficient methods for computing the uniformizations…

Geometric Topology · Mathematics 2020-09-21 Tianqi Wu , Xiaoping Zhu

We show that the generic fiber of a family of smooth $\mathbb{A}^{1}$-ruled affine surfaces always carries an $\mathbb{A}^{1}$-fibration, possibly after a finite extension of the base. In the particular case where the general fibers of the…

Algebraic Geometry · Mathematics 2014-08-07 Adrien Dubouloz , Takashi Kishimoto

Let f: X->B be a fibred surface of genus g whose general fibre is a double cover of a smooth curve of genus gamma. We show that, for g > 4gamma+1, the number 4(g-1)/(g-gamma) is a sharp lower bound for the slope of f, proving a conjecture…

Algebraic Geometry · Mathematics 2009-01-14 M. Cornalba , L. Stoppino

We study curve singularities in a smooth surface relative to a smooth boundary curve. We consider the semiuniversal deformations and equisingular deformations of curves with a fixed local intersection number $w$ with the boundary, and prove…

Algebraic Geometry · Mathematics 2025-10-20 Nobuyoshi Takahashi

We study a generalization of constant Gauss curvature -1 surfaces in Euclidean 3-space, based on Lorentzian harmonic maps, that we call pseudospherical frontals. We analyze the singularities of these surfaces, dividing them into those of…

Differential Geometry · Mathematics 2016-08-05 David Brander

We show sharp square function estimates for curves in the plane whose curvature degenerates at a point and estimates sharp up to endpoints for cones over these curves. To this end, for curves of finite type we extend the classical…

Classical Analysis and ODEs · Mathematics 2024-08-15 Robert Schippa