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The Gerstenhaber and Schack cohomology comparison theorem asserts that there is a cochain equivalence between the Hochschild complex of a certain algebra and the usual singular cochain complex of a space. We show that this comparison…

Quantum Algebra · Mathematics 2016-09-07 F. Patras

We give a new computation of Hochschild (co)homology of the exterior algebra, together with algebraic structures, by direct comparison with the symmetric algebra. The Hochschild cohomology is determined to be essentially the algebra of…

K-Theory and Homology · Mathematics 2017-09-18 Michael Wong

The dimension algebra of graded groups is introduced. With the help of known geometric results of extension theory that algebra induces all known results of the cohomological dimension theory. Elements of the algebra are equivalence classes…

Algebraic Topology · Mathematics 2008-02-27 Jerzy Dydak

For a perfect field $k$ of characteristic $p>0$ and for a finite dimensional symmetric $k$-algebra $A$ K\"ulshammer studied a sequence of ideals of the centre of $A$ using the $p$-power map on degree 0 Hochschild homology. In joint work…

Representation Theory · Mathematics 2010-05-17 Alexander Zimmermann

We introduce a persistent Hochschild homology framework for directed graphs. Hochschild homology groups of (path algebras of) directed graphs vanish in degree $i\geq 2$. To extend them to higher degrees, we introduce the notion of…

Algebraic Topology · Mathematics 2023-08-17 Luigi Caputi , Henri Riihimäki

The finitistic dimension conjecture asserts that any finite-dimensional algebra over a field should have finite finitistic dimension. Recently, this conjecture is reduced to studying finitistic dimensions for extensions of algebras. In this…

Representation Theory · Mathematics 2018-05-01 Chengxi Wang , Changchang Xi

We show that the cohomology ring of a finite-dimensional complex pointed Hopf algebra with an abelian group of group-like elements is finitely generated. Our strategy has three major steps. We first reduce the problem to the finite…

Quantum Algebra · Mathematics 2021-08-03 Nicolás Andruskiewitsch , Iván Angiono , Julia Pevtsova , Sarah Witherspoon

A finite-dimensional Hopf algebra is called quasi-split if it is Morita equivalent to a split abelian extension of Hopf algebras. Combining results of Schauenburg and Negron, it is shown that every quasi-split finite-dimensional Hopf…

Quantum Algebra · Mathematics 2024-07-09 Nicolás Andruskiewitsch , Sonia Natale

We prove that a finite von Neumann algebra ${\mathcal A}$ is semisimple if the algebra of affiliated operators ${\mathcal U}$ of ${\mathcal A}$ is semisimple. When ${\mathcal A}$ is not semisimple, we give the upper and lower bounds for the…

Rings and Algebras · Mathematics 2007-10-30 Lia Vas

In previous work, we established a duality between the algebraic de Rham cohomology of a flat algebraic connection on a smooth quasi-projective surface over the complex numbers and the rapid decay homology of the dual connection relying on…

Algebraic Geometry · Mathematics 2015-05-13 Marco Hien

This article is a survey of conjectures and results on reductive algebraic groups having good reduction at a suitable set of discrete valuations of the base field. Until recently, this subject has received relatively little attention, but…

Number Theory · Mathematics 2020-08-18 Andrei S. Rapinchuk , Igor A. Rapinchuk

The Lichtenbaum-Quillen conjecture for smooth complex varieties states that algebraic and topological K-theory with finite coefficients become isomorphic in high degrees. We define the "Lichtenbaum-Quillen dimension" of a variety in terms…

Algebraic Geometry · Mathematics 2026-04-14 Nicolas Addington , Elden Elmanto

We investigate the relationship between smoothness and the relative global dimension of a ring extension. We prove that a smooth commutative algebra $A$ over $B$ has finite relative global dimension $\text{gdim}(A,B)$. Conversely, under a…

Commutative Algebra · Mathematics 2025-11-03 Kostiantyn Iusenko , Eduardo do Nascimento Marcos , Victor do Valle Pretti

Let C be a small category and k a field. There are two interesting mathematical subjects: the category algebra kC and the classifying space |C|=BC. We study the ring homomorphism HH*(kC) --> H*(|C|,k) and prove it is split surjective. This…

Algebraic Topology · Mathematics 2008-07-29 Fei Xu

Recently Alday, Gaiotto and Tachikawa proposed a conjecture relating 4-dimensional super-symmetric gauge theory for a gauge group G with certain 2-dimensional conformal field theory. This conjecture implies the existence of certain…

Algebraic Geometry · Mathematics 2012-01-17 Alexander Braverman , Boris Feigin , Leonid Rybnikov , Michael Finkelberg

Building on the recent determination of the simplicial cohomology groups of the convolution algebra ${\ell}^1({\mathbb Z}_+^k)$ [Gourdeau, Lykova, White, 2005] we investigate what can be said for cohomology of this algebra with more general…

Functional Analysis · Mathematics 2010-03-09 Yemon Choi

In a recent manuscript, D.Vogan conjectures that four canonical globalizations of Harish-Chandra modules commute with certain n-cohomology groups. In this article we prove that Vogan's conjecture holds for one of the globalizations if and…

Representation Theory · Mathematics 2008-04-03 Tim Bratten , Sergio Corti

We observe that there exists an associative finite dimensional $\mathbb{C}$-algebra $A$ of finite global dimension, such that the bounded derived category $D^b(A)$ of finite dimensional $A$-modules admits an admissible subcategory…

Representation Theory · Mathematics 2023-04-18 Martin Kalck

In this paper, we study finiteness criteria for the Gorenstein homological dimension of groups over a commutative ring of finite Gorenstein weak global dimension and provide estimates for the Gorenstein weak global dimension of group rings.…

Commutative Algebra · Mathematics 2025-03-07 Ilias Kaperonis , Dimitra-Dionysia Stergiopoulou

Koszul property was generalized to homogeneous algebras of degree N>2 in [5], and related to N-complexes in [7]. We show that if the N-homogeneous algebra A is generalized Koszul, AS-Gorenstein and of finite global dimension, then one can…

Quantum Algebra · Mathematics 2007-05-23 Roland Berger , Nicolas Marconnet