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We prove several results on reductive group schemes over LG-rings, e.g., existence of maximal tori and conjugacy of parabolic subgroups. These were proven in SGA3 for the special case of semilocal rings. We apply these results to establish…

Algebraic Geometry · Mathematics 2025-03-03 Philippe Gille , Erhard Neher

Let $A$ be an Azumaya algebra over a field. If $G$ is the group of automorphisms of $A$ and $X$ denotes a projective homogeneous variety under $G$, we construct in a very explicit way and under suitable hypotheses a bundle $\mathcal{V}$ on…

Algebraic Geometry · Mathematics 2008-01-25 Franck Doray

This paper investigates the homology of the Brauer algebras, interpreted as appropriate Tor-groups, and shows that it is closely related to the homology of the symmetric group. Our main results show that when the defining parameter of the…

Algebraic Topology · Mathematics 2023-06-13 Rachael Boyd , Richard Hepworth , Peter Patzt

A natural question is to determine which algebraic stacks are qoutient stacks. In this paper we give some partial answers and relate it to the old question of whether, for a scheme X, the natural map from the Brauer goup (equivalence…

Algebraic Geometry · Mathematics 2016-09-07 D. Edidin , B. Hassett , A. Kresch , A. Vistoli

We consider the Brauer group ${\rm BM}'(k,G)$ of a group $G$ (finite or infinite) over a commutative ring $k$ with identity. A split exact sequence $$1\longrightarrow {\rm Br}'(k)\longrightarrow {\rm BM}'(k,G)\longrightarrow {\rm Gal}(k,G)…

Rings and Algebras · Mathematics 2007-05-23 S. Caenepeel , F. Van Oystaeyen , Y. H. Zhang

This is a textbook on arithmetic geometry with special regard to unramified Brauer groups of algebraic varieties. The topics include Galois cohomology, Brauer groups, obstructions to stable rationality, arithmetic and geometry of quadrics,…

Algebraic Geometry · Mathematics 2018-06-11 Sergey Gorchinskiy , Constantin Shramov

We describe the derived Picard group of an Azumaya algebra A on an affine scheme X in terms of global sections of the constant sheaf of integers on X, the Picard group of X, and the stabilizer of the Brauer class of A under the action of…

Rings and Algebras · Mathematics 2017-01-03 Cris Negron

Using twisted and formal-local methods, we prove that every separated algebraic space which is the (open/flat) pushout of affine schemes has enough Azumaya algebras. As a corollary we show that, under mild hypothesis, every cohomological…

Algebraic Geometry · Mathematics 2022-07-13 Siddharth Mathur

Using a reduction of the Galois cohomology of a linear algebraic group $G$ to that of a certain finite subquotient, we give different formulas allowing the calculation of the unramified algebraic Brauer group of a homogeneous space…

Algebraic Geometry · Mathematics 2017-09-06 Giancarlo Lucchini Arteche

A new class of associative algebras referred to as affine walled Brauer algebras are introduced. These algebras are free with infinite rank over a commutative ring containing 1. Then level two walled Brauer algebras over C are defined,…

Representation Theory · Mathematics 2013-05-03 Hebing Rui , Yucai Su

We define a generalization of the Brauer group $\operatorname{H}_\mathrm{B}^{n}(X)$ for an equi-dimensional scheme $X$ and $n>0$. In the case where $X$ is the spectrum of a local ring of a smooth algebra over a discrete valuation ring,…

Number Theory · Mathematics 2020-11-18 Makoto Sakagaito

We study the Brauer groups of affine surfaces that are complements of singular hyperplane sections of smooth cubic surfaces over a field $k$ of characteristic $0$. We determine the Brauer group over the algebraic closure as a Galois module…

Algebraic Geometry · Mathematics 2025-10-30 Abdulmuhsin Alfaraj

Suppose $A$ is an Azumaya algebra over a ring $R$ and $\sigma$ is an involution of $A$ extending an order-$2$ automorphism $\lambda:R\to R$. We say $\sigma$ is extraordinary if there does not exist a Brauer-trivial Azumaya algebra…

Rings and Algebras · Mathematics 2025-07-02 Uriya First , Ben Williams

In this paper, we will present Brauer algebras associated to spherical Coxeter groups of type H3 and H4, which are also can be regarded as subalgebras of Brauer algebras D6 and E8 by Muhlherr's admissible partition. Also some basic…

Representation Theory · Mathematics 2013-05-29 Shoumin Liu

In this paper, we define a generalization of the Brauer groups by using Bloch's cycle complex on etale site. We prove the Gersten conjecture of generalized Brauer group on some cases. As an application we prove the Gersten conjecture of the…

Number Theory · Mathematics 2016-11-08 Makoto Sakagaito

We show, that for a morphism of schemes from X to Y, that is a finite modification in finitely many closed points, a cohomological Brauer class on Y is represented by an Azumaya algebra if its pullback to X is represented by an Azumaya…

Algebraic Geometry · Mathematics 2023-04-17 Johannes Fischer

We will present an algebra related to the Coxeter group of type I2n which can be taken as a twisted subalgebra in Brauer algebra of type A_{n-1}. Also we will describe some properties of this algebra.

Representation Theory · Mathematics 2012-07-26 Shoumin Liu

We study the question of whether the Brauer group is isomorphic to the cohomological one in spectral algebraic geometry. For this, we prove the compact generation of the derived category of twisted sheaves for quasi-compact spectral…

Algebraic Geometry · Mathematics 2020-02-20 Chang-Yeon Chough

We give an interpretation of the Brauer group of a purely inseparable extension of exponent 1, in terms of restricted Lie-Rinehart cohomology. In particular, we define and study the category $p$-$\rm{LR}(A)$ of restricted Lie-Rinehart…

Rings and Algebras · Mathematics 2011-10-14 Ioannis Dokas

The main theorem (Theorem 4.1) of this paper claims that any ring morphism from an Azumaya algebra of constant rank over a commutative ring to another one of the same constant rank and over a reduced commutative ring induces a ring morphism…

Rings and Algebras · Mathematics 2016-09-07 Kossivi Adjamagbo , Jean-Yves Charbonnel , Arno Van Den Essen