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In this paper we consider the Brauer groups of algebraic stacks and GIT quotients: the only algebraic stacks we consider in this paper are quotient stacks [X/G], where X is a smooth scheme of finite type over a field k, and G is a linear…

Algebraic Geometry · Mathematics 2021-06-29 Jaya Iyer , Roy Joshua

A duality theorem of the bounded derived category of quasi-finite comodules over an artinian coalgebra is established. Let $A$ be a noetherian complete basic semiperfect algebra over an algebraically closed field, and $C$ be its dual…

Rings and Algebras · Mathematics 2010-10-07 J. -W. He , B. Torrecillas , F. Van Oystaeyen , Y. Zhang

We prove some $\ell$-independence results on local constancy of \'etale cohomology of rigid analytic varieties. As a result, we show that a closed subscheme of a proper scheme over an algebraically closed complete non-archimedean field has…

Algebraic Geometry · Mathematics 2020-10-08 Kazuhiro Ito

This note will present a new proof of the fact that every uniformly bounded group of invertible elements in a finite von Neumann algebra is similar to a unitary group. The proof involves metric geometric arguments in the non-positively…

Operator Algebras · Mathematics 2017-05-04 Martin Miglioli

We characterize the topology of the Glimm space of a separable C*-algebra and extend the main result of [6] to non-unital AF C*-algebras.

Operator Algebras · Mathematics 2015-09-22 Aldo J. Lazar , Douglas W. B. Somerset

We prove that some skew group algebras have Noetherian cohomology rings, a property inherited from their component parts. The proof is an adaptation of Evens' proof of finite generation of group cohomology. We apply the result to a series…

Representation Theory · Mathematics 2018-05-23 Van C. Nguyen , Sarah Witherspoon

In this paper we generalize an argument of Neukirch from birational anabelian geometry to the case of arithmetic curves. In contrast to the function field case, it seems to be more complicate to describe the position of decomposition groups…

Number Theory · Mathematics 2013-09-12 Alexander Ivanov

In which is developed a new form of superselection sectors of topological origin. By that it is meant a new investigation that includes several extensions of the traditional framework of Doplicher, Haag and Roberts in local quantum…

Mathematical Physics · Physics 2009-03-20 Romeo Brunetti , Giuseppe Ruzzi

The action of Ashtekar's generalized gauge group $\Gb$ on the space $\Ab$ of generalized connections is investigated for compact structure groups $\LG$. First a stratum is defined to be the set of all connections of one and the same gauge…

Mathematical Physics · Physics 2009-10-31 Christian Fleischhack

Rook-Brauer algebras are a family of diagram algebras. They contain many interesting subalgebras: rook algebras, Brauer algebras, Motzkin algebras, Temperley-Lieb algebras and symmetric group algebras. In this paper, we generalize the…

Algebraic Topology · Mathematics 2023-10-11 Daniel Graves

The degenerate affine and affine BMW algebras arise naturally in the context of Schur-Weyl duality for orthogonal and symplectic Lie algebras and quantum groups, respectively. Cyclotomic BMW algebras, affine Hecke algebras, cyclotomic Hecke…

Representation Theory · Mathematics 2011-08-04 Zajj Daugherty , Arun Ram , Rahbar Virk

In this article, we compare the cohomology between the categories of modules of the diagram algebras and the categories of modules of its input algebras. Our main result establishes a sufficient condition for exact split pairs between these…

Representation Theory · Mathematics 2025-02-20 Sulakhana Chowdhury , Geetha Thangavelu

Let G be a reductive group over C. Assume that the Lie algebra g of G has a given grading (g_j) indexed by a cyclic group Z/m such that g_0 contains a Cartan subalgebra of g. The subgroup G_0 of G corresponding to g_0 acts on the variety of…

Representation Theory · Mathematics 2018-05-29 George Lusztig , Zhiwei Yun

We study non-additive operations from algebraic Morava K-theories to oriented cohomology theories in algebraic geometry. For oriented cohomology theory $A$ that has a {$p^n$}-typical formal group law over a $\mathbb{Z}_{(p)}$-algebra we…

Algebraic Geometry · Mathematics 2025-10-08 Pavel Sechin

This paper contains a quite detailed description of the C*-algebra arising from the transformation groupoid of a rational map of degree at least two on the Riemann sphere. The algebra is decomposed stepwise via extensions of familiar…

Operator Algebras · Mathematics 2012-02-14 Klaus Thomsen

We prove that von Neumann algebras and separable nuclear $C^*$-algebras are stable for the Banach-Mazur cb-distance. A technical step is to show that unital almost completely isometric maps between $C^*$-algebras are almost multiplicative…

Operator Algebras · Mathematics 2013-06-26 Eric Ricard , Jean Roydor

We prove the vanishing of bounded cohomology with separable dual coefficients for many groups of interest in geometry, dynamics, and algebra. These include compactly supported structure-preserving diffeomorphism groups of certain manifolds;…

Group Theory · Mathematics 2025-10-30 Caterina Campagnolo , Francesco Fournier-Facio , Yash Lodha , Marco Moraschini

Let an n-algebra mean an algebra over the chain complex of the little n-cubes operad. We give a proof of Kontsevich's conjecture, which states that for a suitable notion of Hochschild cohomology in the category of n-algebras, the Hochschild…

Algebraic Topology · Mathematics 2007-05-23 P. Hu , I. Kriz , A. A. Voronov

We show that every non-Archimedean Polish group $P$ is the outer automorphism group of a countable discrete group $G_P$. Moreover, our construction provides a Borel map $f$ from the Effros space of closed subgroups of the permutation group…

Group Theory · Mathematics 2026-05-26 Jean-Luc Rabideau

Let $A$ be a nondegenerate dimer (or ghor) algebra on a torus, and let $Z$ be its center. Using cyclic contractions, we show the following are equivalent: $A$ is noetherian; $Z$ is noetherian; $A$ is a noncommutative crepant resolution;…

Rings and Algebras · Mathematics 2024-01-02 Charlie Beil