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Related papers: Iterated descent obstructions for algebraic stacks

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We establish the exact overlaps conjecture for iterated functions systems on the real line with algebraic contractions and arbitrary translations.

Dynamical Systems · Mathematics 2020-01-15 Ariel Rapaport

We give an explicitly computable lower bound for the arithmetic self-intersection number of the dualizing sheaf on a large class of arithmetic surfaces. If some technical conditions are satisfied, then this lower bound is positive. In…

Number Theory · Mathematics 2013-07-22 Ulf Kühn , Jan Steffen Müller

We give an explicit description of the Lie algebra of derivations for a class of infinite dimensional algebras which are given by \'etale descent. The algebras under consideration are twisted forms of central algebras over rings, and…

Rings and Algebras · Mathematics 2009-01-30 Arturo Pianzola

We construct a (smooth, projective) surface over the field of rational numbers, which is a counterexample to the Hasse principle not accounted for by the Manin obstruction. The construction relies on the classical 4-descent on elliptic…

alg-geom · Mathematics 2007-05-23 Alexei Skorobogatov

The aim of this article is to investigate the cohomology (l-adic as well as Betti) of schemes, and more generally of certain algebraic stacks, that are proper and smooth over the integers and have the property that there exists a polynomial…

Algebraic Geometry · Mathematics 2008-11-03 Theo van den Bogaart , Bas Edixhoven

We generalize Illusie's definition of the Atiyah class to complexes with quasi-coherent cohomology on arbitrary algebraic stacks. We show that this gives a global obstruction theory for moduli stacks of complexes in algebraic geometry…

Algebraic Geometry · Mathematics 2024-11-20 Nikolas Kuhn

Consider an algorithm computing in a differential field with several commuting derivations such that the only operations it performs with the elements of the field are arithmetic operations, differentiation, and zero testing. We show that,…

Commutative Algebra · Mathematics 2021-08-31 Wei Li , Alexey Ovchinnikov , Gleb Pogudin , Thomas Scanlon

Let X be a smooth variety over a number field k embedded as a degree d subvariety of $\mathbb{P}^n$ and suppose that X is a counterexample to the Hasse principle explained by the Brauer-Manin obstruction. We consider the question of whether…

Number Theory · Mathematics 2019-02-13 Brendan Creutz , Bianca Viray

The aim of this paper is to prove that, in an appropriate setting, every iterative sequence generated by the hybrid steepest descent method is convergent whenever so is every iterative sequence generated by the Halpern type iterative…

Functional Analysis · Mathematics 2020-12-29 Koji Aoyama , Yasunori Kimura

We study the strong approximation for classifying stacks $BG$, where $G$ is a linear algebraic group over a number field $k$. More specifically, we prove that the \'etale Brauer-Manin obstruction is the only obstruction to strong…

Number Theory · Mathematics 2026-04-17 Ajneet Dhillon , Nicole Lemire , Jonathan Martin , Yidi Wang

We formulate and prove a chain level descent property of symplectic cohomology for involutive covers by compact subsets that take into account the natural algebraic structures that are present. The notion of an involutive cover is reviewed.…

Symplectic Geometry · Mathematics 2025-05-01 Umut Varolgunes

We show that various natural algebro-geometric moduli stacks, including the stack of curves, have the property that every Deligne-Mumford gerbe over a field appears as the residual gerbe of one of their points. These gerbes are universal…

Algebraic Geometry · Mathematics 2024-02-02 Daniel Bragg , Max Lieblich

By [R. Bautista, P. Gabriel, A.V Roiter., L. Salmeron, Representation-finite algebras and multiplicative basis. Invent. Math. 81 (1985) 217-285.], a finite-dimensional algebra having finitely many isoclasses of indecomposable…

Representation Theory · Mathematics 2007-11-17 Andrej V. Roiter , Vladimir V. Sergeichuk

We give a direct combinatorial proof that the product of two descent classes in a symmetric group is a sum of descent classes. The proof is based on the fact that the group product gives a covering map when descent classes are endowed with…

Combinatorics · Mathematics 2025-06-09 Philippe Biane

Recently, a method to compute the implicit equation of a parametrized hypersurface has been developed by the authors. We address here some questions related to this method. First, we prove that the degree estimate for the stabilization of…

Commutative Algebra · Mathematics 2007-09-13 Laurent Buse , Marc Chardin , Jean-Pierre Jouanolou

Let $X$ be any rational surface. We construct a tilting bundle $T$ on $X$. Moreover, we can choose $T$ in such way that its endomorphism algebra is quasi-hereditary. In particular, the bounded derived category of coherent sheaves on $X$ is…

Algebraic Geometry · Mathematics 2017-06-27 Lutz Hille , Markus Perling

For a smooth proper scheme over a local field of mixed characteristics which has semistable reduction we define the category of its semistable etale sheaves and under certain hypothesis we prove the appropriate semistable comparison…

Algebraic Geometry · Mathematics 2012-12-18 Fabrizio Andreatta , Adrian Iovita

Let $S$ be a finite set of primes. We prove that a form of finite Galois descent obstruction is the only obstruction to the existence of $\mathbb{Z}_{S}$-points on integral models of Hilbert modular varieties, extending a result of D.Helm…

Number Theory · Mathematics 2021-07-01 Gregorio Baldi , Giada Grossi

We study the problem of when a topological vector bundle on a smooth complex affine variety admits an algebraic structure. We prove that all rank $2$ topological complex vector bundles on smooth affine quadrics of dimension $11$ over the…

Algebraic Geometry · Mathematics 2017-06-07 Aravind Asok , Jean Fasel

We study intersection theory for differential algebraic varieties. Particularly, we study families of differential hypersurface sections of arbitrary affine differential algebraic varieties over a differential field. We prove the…

Logic · Mathematics 2015-02-25 James Freitag