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Let X be a projective variety which is algebraic Lang hyperbolic. We show that Lang's conjecture holds (one direction only): X and all its subvarieties are of general type and the canonical divisor K_X is ample at smooth points and Kawamata…

Algebraic Geometry · Mathematics 2019-07-08 Fei Hu , Sheng Meng , De-Qi Zhang

Algebraic surfaces in the complex projective space with a high number of A-type singularities have been presented in a recent paper. We extend the construction in order to obtain lower bounds for the maximal number of A singularities for…

Algebraic Geometry · Mathematics 2026-05-25 Juan García Escudero

A minimal surface of general type with $p_g(S)=0$ satisfies $1\le K^2\le 9$ and it is known that the image of the bicanonical map $\fie$ is a surface for $K_S^2\geq 2$, whilst for $K^2_S\geq 5$, the bicanonical map is always a morphism. In…

Algebraic Geometry · Mathematics 2007-05-23 M. Mendes Lopes , R. Pardini

We consider the moduli space of log smooth pairs formed by a cubic surface and an anticanonical divisor. We describe all compactifications of this moduli space which are constructed using Geometric Invariant Theory and the anticanonical…

Algebraic Geometry · Mathematics 2020-10-02 Patricio Gallardo , Jesus Martinez-Garcia

Inspired by the ideas of the minimal model program, Shepherd-Barron, Koll\'ar, and Alexeev have constructed a geometric compactification for the moduli space of surfaces of log general type. In this paper, we discuss one of the simplest…

Algebraic Geometry · Mathematics 2016-02-18 Radu Laza

We introduce the notion of generalized MR log canonical surfaces and establish the minimal model theory for generalized MR log canonical surfaces in full generality.

Algebraic Geometry · Mathematics 2020-12-03 Osamu Fujino

A good canonical projection of a surface $S$ of general type is a morphism to the 3-dimensional projective space P^3 given by 4 sections of the canonical line bundle. To such a projection one associates the direct image sheaf F of the…

Algebraic Geometry · Mathematics 2007-05-23 Fabrizio Catanese , Frank Olaf Schreyer

Let $X$ be a minimal surface of general type and maximal Albanese dimension with irregularity $q\geq 2$. We show that $K_X^2\geq 4\chi(\mathcal O_X)+4(q-2)$ if $K_X^2<\frac92\chi(\mathcal O_X)$, and also obtain the characterization of the…

Algebraic Geometry · Mathematics 2015-04-28 Xin Lu , Kang Zuo

We establish the minimal model program for log canonical and Q-factorial surfaces over excellent base schemes.

Algebraic Geometry · Mathematics 2018-01-22 Hiromu Tanaka

We classify minimal surfaces $S$ with $p_g=q=2$ and $K_S^2=5$ or $6$.

Algebraic Geometry · Mathematics 2024-01-23 Jiabin Du , Zhi Jiang , Guoyun Zhang

In this paper, we prove that if a $3$-dimensional quasi-projective variety $X$ over an algebraically closed field of characteristic $p>3$ has only log canonical singularities, then so does a general hyperplane section $H$ of $X$. We also…

Algebraic Geometry · Mathematics 2025-09-17 Kenta Sato

In the paper we compute the global log canonical thresholds of the secondary Burniat surfaces with $K^2 = 5$. Furthermore, we establish optimal lower bounds for the log canonical thresholds of members in pluricanonical sublinear systems of…

Algebraic Geometry · Mathematics 2024-01-10 Nguyen Bin , Jheng-Jie Chen , YongJoo Shin

We make a very detailed analysis of the numerical properties of effective divisors whose support is contained in the exceptional locus of a birational morphism of smooth projective surfaces. As an application we extend Miyaoka's inequality…

Algebraic Geometry · Mathematics 2022-07-19 Vicente Lorenzo , Margarida Mendes Lopes , Rita Pardini

We analyze the configurations of conics and lines on a special class of Kummer octic surfaces. In particular, we bound the number of conics by $176$ and show that there is a unique surface with $176$ conics, all irreducible: it admits a…

Algebraic Geometry · Mathematics 2024-08-20 Alex Degtyarev

Let $\bar{Y}$ be a normal surface that is the canonical $\mu_2$- or $\alpha_2$-covering of a classical or supersingular Enriques surface in characteristic $2$. We determine all possible configurations of singularities on $\bar{Y}$, and for…

Algebraic Geometry · Mathematics 2022-07-26 Yuya Matsumoto

We determine the fixed locus of the anticanonical complete linear system of a given anticanonical rational surface. The case of a geometrically ruled rational surface is fully studied, e.g., the monoid of numerically effective divisor…

Algebraic Geometry · Mathematics 2012-01-25 Jesús Adrian Cerda Rodríguez , Gioia Failla , Mustapha Lahyane , Osvaldo Osuna Castro

Chapters : Old and new inequalities; Surfaces with $\chi=1$ and the bicanonical map; Surfaces with $p_g=4$; Surfaces isogeneous to a product, Beauville surfaces and the absolute Galois group;Lefschetz pencils and braid monodromies;DEF, DIFF…

Algebraic Geometry · Mathematics 2009-09-29 Ingrid Bauer , Fabrizio Catanese , Roberto Pignatelli

In this paper, we prove the non-vanishing and some special cases of the abundance for log canonical threefold pairs over an algebraically closed field $k$ of characteristic $p > 3$. More precisely, we prove that if $(X,B)$ be a projective…

Algebraic Geometry · Mathematics 2024-02-06 Zheng Xu

We continue our study of the relation between log minimal models and various types of Zariski decompositions. Let $(X,B)$ be a projective log canonical pair. We will show that $(X,B)$ has a log minimal model if either $K_X+B$ birationally…

Algebraic Geometry · Mathematics 2013-02-19 Caucher Birkar , Zhengyu Hu

We construct a canonical basis of two-cycles, on a $K3$ surface, in which the intersection form takes the canonical form $2E_8(-1) \oplus 3H$. The basic elements are realized by formal sums of smooth submanifolds.

Algebraic Topology · Mathematics 2019-04-10 Iskander A. Taimanov