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We discuss the flatness property of some fiber type contractions of complex smooth projective varieties of arbitrary dimensions. We relate the flatness of some morphisms having one-dimensional fibers with their conic bundles structures,…

Algebraic Geometry · Mathematics 2019-06-27 Eleonora Anna Romano

Let $X$ be a smooth projective variety with a nef anticanonical divisor over an algebraically closed field of characteristic $p>0$. In this paper, we establish a precise structure of $X$ under the condition that $a_X: X \to {\rm Alb}(X)$ is…

Algebraic Geometry · Mathematics 2025-10-21 Tongji Gao , Zhan Li , Lei Zhang

We explicitly describe the Albanese morphism of a hyperelliptic variety, i.e., the quotient $X$ of an abelian variety $A$ by a finite group $G$ acting freely and not only by translations, by giving a description of the Albanese variety and…

Algebraic Geometry · Mathematics 2024-11-25 Pieter Belmans , Andreas Demleitner , Pedro Núñez

An extremal curve germ is the analytic germ of a threefold with terminal singularities along a reduced complete curve admitting a contraction whose fibers have dimension at most one. The aim of the present paper is to review the results…

Algebraic Geometry · Mathematics 2019-09-04 Shigefumi Mori , Yuri Prokhorov

Let $X$ be a projective variety admitting a polarized (or more generally, int-amplified) endomorphism. We show: there are only finitely many contractible extremal rays; and when $X$ is $\mathbb{Q}$-factorial normal, every minimal model…

Algebraic Geometry · Mathematics 2020-06-11 Sheng Meng , De-Qi Zhang

We prove that affine maps are uniquely extremal quasiconformal maps on the complement of a well distribute set in the complex plane answering a conjecture from \cite{markovic}. We construct the required Reich sequence using Bergman…

Complex Variables · Mathematics 2025-03-20 Qiliang Luo , Vladimir Marković

The quotient singularities of dimensions two and three obtained from polyhedral groups and the corresponding binary polyhedral groups admit natural resolutions of singularities as Hilbert schemes of regular orbits whose exceptional fibres…

Algebraic Geometry · Mathematics 2007-05-23 Samuel Boissiere , Alessandra Sarti

In this paper the three-dimensional divisorial contractions $f\colon Y\to (X\ni P)$ are classified provided that $\Exc f=E$ is an irreducible divisor, $f(E)=P$, the variety $Y$ has canonical singularities and $(X\ni P)$ is a toric terminal…

Algebraic Geometry · Mathematics 2014-11-24 S. A. Kudryavtsev

Let N_0 = C^2/H be an isolated quotient singularity with H in U (2) a finite subgroup. We show that for any Q-Gorenstein smoothings of N_0 a nearby fiber admits ALE Ricci-flat Kahler metrics in any Kahler class. Moreover, we generalize…

Differential Geometry · Mathematics 2011-02-15 Ioana Suvaina

Let $X$ be a smooth projective variety defined over an algebraically closed field of positive characteristic $p$ whose tangent bundle is nef. We prove that $X$ admits a smooth morphism $X \to M$ such that the fibers are Fano varieties with…

Algebraic Geometry · Mathematics 2020-12-18 Akihiro Kanemitsu , Kiwamu Watanabe

Let $X$ be a normal variety over the field of complex numbers with log terminal singularities and the canonical divisor $K_X$ being ${\bf Q}$-Gorenstein. Assume that $L$ is an ample line bundle over $X$ and $\phi: X\to Y$ is a morphism…

alg-geom · Mathematics 2008-02-03 Marco Andreatta , Jarosław A. Wiśniewski

Relations among fundamental invariants play an important role in algebraic geometry. It is known that an $n$-dimensional variety of general type with nef canonical divisor and canonical singularities, whose image $Y$ under the canonical map…

Algebraic Geometry · Mathematics 2021-01-12 Purnaprajna Bangere , Jungkai Alfred Chen , Francisco Javier Gallego

Let $X$ be a smooth affine algebraic variety over the field of complex numbers which is contractible. Then every algebraic $G$-torsor on $X$ is algebraically trivial if $G$ is a semi-simple algebraic group. We also show that if $X$ is a…

Algebraic Geometry · Mathematics 2015-07-28 S. Subramanian

We study singularities obtained by the contraction of the maximal divisor in compact (non kaehlerian) surfaces which contain global spherical shells. These singularities are of genus 1 or 2, may be Q-Gorenstein, numerically Gorenstein or…

Complex Variables · Mathematics 2008-01-07 Georges Dloussky

In this short note, we will show the following weak evidence of S. Lang conjecture over function fields. Let f : X ---> Y be a projective and surjective morphism of algebraic varieties over an algebraically closed field k of characteristic…

alg-geom · Mathematics 2008-02-03 Atsushi Moriwaki

Let $f:X\to S$ be an extremal contraction from a threefolds with terminal singularities onto a surface (so called Mori conic bundle). We study some particular cases of such contractions: quotients of usual conic bundles and index two…

alg-geom · Mathematics 2010-05-11 Yuri G Prokhorov

Let $X$ be an equivariant embedding of a connected reductive group $G$ over an algebraically closed field $k$ of positive characteristic. Let $B$ denote a Borel subgroup of $G$. A $G$-Schubert variety in $X$ is a subvariety of the form…

Algebraic Geometry · Mathematics 2008-09-10 Xuhua He , Jesper Funch Thomsen

We introduce and investigate multicomplex configurations, a class of projective varieties constructed via specialization of the polarizations of Artinian monomial ideals. Building upon geometric polarization and geometric vertex…

Commutative Algebra · Mathematics 2025-07-15 Patricia Klein , Jenna Rajchgot , Alexandra Seceleanu

Let X be the blow-up of a smooth projective 4-fold Y along a smooth curve C and let E be the exceptional divisor. Assume that X is a Fano manifold and has an elementary extremal contraction $\phi: X \to Z$ of (3,1)-type such that E is…

Algebraic Geometry · Mathematics 2007-10-10 Toru Tsukioka

In this paper we discuss the geometry of affine Deligne Lusztig varieties with very special level structure, determining their dimension and connected and irreducible components. As application, we prove the Grothendieck conjecture for…

Algebraic Geometry · Mathematics 2020-12-21 Paul Hamacher