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This paper explores the cohomological consequences of the existence of moduli spaces for flat bundles with bounded rank and irregularity at infinity and gives unconditional proofs. Namely, we prove the existence of a universal bound for the…

Algebraic Geometry · Mathematics 2025-02-26 Haoyu Hu , Jean-Baptiste Teyssier

It is conjectured that the canonical models of varieties (not of general type) are bounded when the Iitaka volume is fixed. We confirm this conjecture when the general fibers of the corresponding Iitaka fibration are in a fixed bounded…

Algebraic Geometry · Mathematics 2025-09-17 Junpeng Jiao

We show that the family of semi log canonical pairs with ample log canonical class and with fixed volume is bounded.

Algebraic Geometry · Mathematics 2017-09-22 Christopher Hacon , James McKernan , Chenyang Xu

In this paper, we study the adjoint foliated structures of the form $K_{\mathcal{F}}+D$ on algebraic surfaces, with particular focus on their minimal and canonical models. We investigate the effective behavior of the multiple linear system…

Algebraic Geometry · Mathematics 2025-05-26 Jun Lu , Xiaohang Wu , Shi Xu

Surfaces of general type with positive second Segre number are known to have big cotangent bundle. We give a new criterion ensuring that a surface of general type with canonical singularities has a minimal resolution with big cotangent…

Algebraic Geometry · Mathematics 2015-01-14 Xavier Roulleau , Erwan Rousseau

The purpose of this article is to study the deformations of smooth surfaces $X$ of general type whose canonical map is a finite, degree 2 morphism onto a minimal rational surface or onto $\mathbf F_1$, embedded in projective space by a very…

Algebraic Geometry · Mathematics 2010-06-01 Francisco Javier Gallego , Miguel González , Bangere P. Purnaprajna

Stable surfaces and their log analogues are the type of varieties naturally occuring as boundary points in moduli spaces. We extend classical results of Kodaira and Bombieri to this more general setting: if $(X,\Delta)$ is a stable log…

Algebraic Geometry · Mathematics 2014-04-15 Wenfei Liu , Sönke Rollenske

We introduce a new invariant, the real (logarithmic)-Kodaira dimension, that allows to distinguish smooth real algebraic surfaces up to birational diffeomorphism. As an application, we construct infinite families of smooth rational real…

Algebraic Geometry · Mathematics 2023-06-22 Jérémy Blanc , Adrien Dubouloz

The Kodaira dimension of Shimura varieties has been studied by many people. Kondo and Gritsenko-Hulek-Sankaran studied the singularities of orthogonal Shimura varieties related to the moduli spaces of polarized K3 surfaces. They proved that…

Number Theory · Mathematics 2022-04-05 Yota Maeda

In this paper, we study the behavior of the sets of volumes of the form $\mathrm{vol}(X,K_X+B+M)$, where $(X,B)$ is a log canonical pair, and $M$ is a nef $\mathbb{R}$-divisor. After a first analysis of some general properties, we focus on…

Algebraic Geometry · Mathematics 2021-08-12 Stefano Filipazzi

We prove that a log surface has only finitely many weakly log canonical projective models with klt singularities up to log isomorphism, by reducing the problem to the boundedness of their polarization.

Algebraic Geometry · Mathematics 2025-10-17 Daniil Serebrennikov

We fix some gaps of a proof of Xiao's conjecture on canonically fibered surfaces of relative genus 5 by the second author. Our argument simplifies the original proof and gives a much better bound on the geometric genus of the surface. Also…

Algebraic Geometry · Mathematics 2025-06-03 Houari Benammar Ammar , Xi Chen , Nathan Grieve

In this paper, we generalise the theory of complements to log canonical log fano varieties and prove boundedness of complements for them in dimension less than or equal to 3. We also prove some boundedness results for the canonical index of…

Algebraic Geometry · Mathematics 2019-01-15 Yanning Xu

A smooth complex variety satisfies the Generalized Jacobian Conjecture if all its \'etale endomorphisms are proper. We study the conjecture for $\mathbb{Q}$-acyclic surfaces of negative Kodaira dimension. We show that $G$-equivariant…

Algebraic Geometry · Mathematics 2019-04-30 Adrien Dubouloz , Karol Palka

We show that the number of deformation types of canonically polarized manifolds over an arbitrary variety with proper singular locus is finite, and that this number is uniformly bounded in any finite type family of base varieties. As a…

Algebraic Geometry · Mathematics 2019-04-08 Sandor J. Kovacs , Max Lieblich

We give some explicit upper bounds on the effective birationality of the canonical or anti-canonical system for a singular surface. In particular, we show that for any surface $X$ with $\epsilon$-lc singularity and the canonical divisor…

Algebraic Geometry · Mathematics 2025-08-26 Pinxian Bie

Shafarevich's hyperbolicity conjecture asserts that a family of curves over a quasi-projective 1-dimensional base is isotrivial unless the logarithmic Kodaira dimension of the base is positive. More generally it has been conjectured by…

Algebraic Geometry · Mathematics 2007-05-23 Stefan Kebekus , Sandor J. Kovacs

Let $X$ be a Gorenstein minimal projective 3-fold with at worst locally factorial terminal singularities. Suppose the canonical map is of fiber type. Denote by $F$ a smooth model of a generic irreducible component in fibers of the canonical…

Algebraic Geometry · Mathematics 2007-05-23 Meng Chen

We give a self contained proof using Seiberg Witten invariants that for K\"ahler surfaces with non negative Kodaira dimension (including those with $p_g = 0$) the canonical class of the minimal model and the $(-1)$-curves, are oriented…

alg-geom · Mathematics 2008-02-03 Rogier Brussee

We classify irreducible d-semistable degenerations of primary Kodaira surfaces. As an application we construct a canonical completion for the moduli space of primary Kodaira surfaces.

Algebraic Geometry · Mathematics 2007-05-23 Stefan Schroeer , Bernd Siebert