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We show that up to potential isogeny, there are only finitely many abelian varieties of dimension $d$ defined over a number field $K$, such that for any finite place $v$ outside a fixed finite set $S$ of places of $K$ containing the…

Number Theory · Mathematics 2022-01-04 Plawan Das , C. S. Rajan

Let $K$ be a field which is complete for a discrete valuation. We prove a logarithmic version of the N\'eron-Ogg-Shafarevich criterion: if $A$ is an abelian variety over $K$ which is cohomologically tame, then $A$ has good reduction in the…

Algebraic Geometry · Mathematics 2016-10-25 Alberto Bellardini , Arne Smeets

We prove existence of reflexive sheaves on singular surfaces and threefolds with prescribed numerical invariants and study their moduli.

Algebraic Geometry · Mathematics 2010-04-23 Elizabeth Gasparim , Thomas Köppe

We prove a Neron--Ogg--Shafarevich type criterion for good reduction of K3 surfaces, which states that a K3 surface over a complete discrete valuation field has potential good reduction if its $l$-adic cohomology group is unramified. We…

Algebraic Geometry · Mathematics 2017-01-06 Yuya Matsumoto

We prove the Shafarevich conjecture for varieties with globally generated cotangent bundle, subject to mild numerical conditions.

Algebraic Geometry · Mathematics 2025-03-27 Thomas Krämer , Marco Maculan

Let $A$ be an abelian scheme of dimension at least four over a $\mathbb{Z}$-finitely generated integral domain $R$ of characteristic zero, and let $L$ be an ample line bundle on $A$. We prove that the set of smooth hypersurfaces $D$ in $A$…

Algebraic Geometry · Mathematics 2022-10-05 Ariyan Javanpeykar , Siddharth Mathur

Presentaremos una nueva demostraci\'on del teorema de Shafarevich sobre finitud de curvas el\'ipticas con buena reducci\'on fuera de un conjunto finito de primos dado. Esto da un nuevo punto de entrada a teoremas fundamentales de finitud…

Number Theory · Mathematics 2026-01-13 Hector Pasten

Using the Shioda-Tate theorem and an adaptation of Silverman's specialization theorem, we reduce the specialization of Mordell-Weil ranks for abelian varieties over fields finitely generated over infinite finitely generated fields $k$ to…

Number Theory · Mathematics 2023-01-31 Timo Keller

For a smooth finite cyclic covering over a projective space of dimension greater than one, we show that the group of automorphisms acts faithfully on the cohomology except for a few cases. In characteristic zero, we study the equivariant…

Algebraic Geometry · Mathematics 2021-12-02 Renjie Lyu , Xuanyu Pan

Let X be a normal connected complex algebraic variety equipped with a semisimple complex representation of its fundamental group. Then, under a maximality assumption, we prove that the covering space of X associated to the kernel of the…

Algebraic Geometry · Mathematics 2023-05-18 Yohan Brunebarbe

We give a survey on the theory of representation-finite and certain minimal representation-infinite algebras.The main goals are the existence of multiplicative bases and of coverings with good properties. Both are attained via…

Representation Theory · Mathematics 2013-02-06 Klaus Bongartz

We establish the geometric Shafarevich boundedness conjecture for the moduli stack of stable minimal models, including in particular the moduli stack of KSB pairs.

Algebraic Geometry · Mathematics 2026-05-12 Junchao Shentu

In this paper we show that any smoothable complex projective variety, smooth in codimension two, with klt singularities and numerically trivial canonical class admits a finite cover, \'etale in codimension one, that decomposes as a product…

Algebraic Geometry · Mathematics 2017-04-07 Stéphane Druel , Henri Guenancia

In the prequel to this paper, two versions of Le Potier's strange duality conjecture for sheaves over abelian surfaces were studied. A third version is considered here. In the current setup, the isomorphism involves moduli spaces of sheaves…

Algebraic Geometry · Mathematics 2014-02-28 Barbara Bolognese , Alina Marian , Dragos Oprea , Kota Yoshioka

Let $K$ denote a number field and a finite set $S$ of places of $K$ and $\phi:\PP^n\rightarrow\PP^n$ be rational morphism defined over $K$. The main result of this paper proves that there are only finitely many twists of $\phi$ defined over…

Number Theory · Mathematics 2013-08-30 Brian Stout

In this paper we consider ideal sheaves associated to the singular loci of a divisor in a linear system $|L|$ of an ample line bundle on a complex abelian variety. We prove an effective result on their (continuous) global generation, after…

Algebraic Geometry · Mathematics 2008-03-28 Luigi Lombardi , Francesco Malaspina

We show the existence of good hyperplane sections for schemes over discrete valuation rings with good or (quasi) semistable reduction, and the existence of good Lefschetz pencils for schemes with good reduction or ordinary quadratic…

Algebraic Geometry · Mathematics 2009-11-10 Uwe Jannsen , Shuji Saito

We give a theory of id\`eles with coefficients for smooth surfaces over a field. It is an analogue of Beilinson/Huber's theory of higher ad\`eles, but handling cycle module sheaves instead of quasi-coherent ones. We prove that they give a…

Number Theory · Mathematics 2019-03-18 Oliver Braunling

We prove that a cyclic cover of a smooth complex projective variety is Brody hyperbolic if its branch divisor is a generic small deformation of a large enough multiple of a Brody hyperbolic base-point-free ample divisor. We also show the…

Algebraic Geometry · Mathematics 2018-06-19 Yuchen Liu

We show that the $\ell$-adic Tate conjecture for divisors on smooth proper varieties over finitely generated fields of positive characteristic follows from the $\ell$-adic Tate conjecture for divisors on smooth projective surfaces over…

Algebraic Geometry · Mathematics 2021-05-11 Emiliano Ambrosi