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For a Cohen-Macaulay ring $R$, we exhibit the equivalence of the bounded derived categories of certain resolving subcategories, which, amongst other results, yields an equivalence of the bounded derived category of finite length and finite…

K-Theory and Homology · Mathematics 2015-05-26 William Sanders , Sarang Sane

The notion of Hochschild homology of a dg algebra admits a natural dualization, the coHochschild homology of a dg coalgebra, introduced in arXiv:0711.1023 by Hess, Parent, and Scott as a tool to study free loop spaces. In this article we…

Algebraic Topology · Mathematics 2020-07-15 Kathryn Hess , Brooke Shipley

We define and study the Hochschild (co)homology of the second kind (known also as the Borel-Moore Hochschild homology and the compactly supported Hochschild cohomology) for curved DG-categories. An isomorphism between the Hochschild…

Category Theory · Mathematics 2012-06-18 Alexander Polishchuk , Leonid Positselski

We establish a large class of homotopy coherent Morita-equivalences of Dold-Kan type relating diagrams with values in any weakly idempotent complete additive $\infty$-category; the guiding example is an $\infty$-categorical Dold-Kan…

Representation Theory · Mathematics 2022-03-18 Tashi Walde

We use the dimension and the Lie algebra structure of the first Hochschild cohomology group to distinguish some algebras of dihedral, semi-dihedral and quaternion type up to stable equivalence of Morita type. In particular, we complete the…

Representation Theory · Mathematics 2018-05-30 Rachel Taillefer

We define the appropriate homological setting to study deformation theory of complete locally convex (curved) dg-algebras based on Positselski's contraderived categories. We define the corresponding Hochschild complex controlling…

Quantum Algebra · Mathematics 2025-12-25 Patrick Antweiler

We show for an affine variety $X$, the derived category of quasi-coherent $D$-modules is equivalent to the category of DG modules over an explicit DG algebra, whose zeroth cohomology is the ring of Grothendieck differential operators…

Algebraic Geometry · Mathematics 2022-01-19 Haiping Yang

We continue the work initiated in arXiv:1206.3645, where we introduced a new stable symmetric monoidal $(\infty,1)$-category $SH_{nc}$ encoding a motivic stable homotopy theory for the noncommutative spaces of Kontsevich and obtained a…

K-Theory and Homology · Mathematics 2013-06-18 Marco Robalo

In this paper we investigate homologically finite-dimensional objects in the derived category of a given small dg-enhanced triangulated category. Using these we define reflexivity, hfd-closedness, and the Gorenstein property for…

Algebraic Geometry · Mathematics 2024-12-02 Alexander Kuznetsov , Evgeny Shinder

When studying deformations of an $A$-module $M$, Laudal and Yau showed that one can consider 1-cocycles in the Hochschild cohomology of $A$ with coefficients in the bi-module $End_k(M).$ With this in mind, the use of higher order Hochschild…

Commutative Algebra · Mathematics 2015-04-20 Bruce R. Corrigan-Salter

Given a finite modular tensor category, we associate with each compact surface with boundary a cochain complex in such a way that the mapping class group of the surface acts projectively on its cohomology groups. In degree zero, this action…

Quantum Algebra · Mathematics 2023-09-19 Simon Lentner , Svea Nora Mierach , Christoph Schweigert , Yorck Sommerhaeuser

We show that for a noetherian algebra $A$ whose bounded dg derived category is smooth, the singular Hochschild cohomology (=Tate--Hochschild cohomology) is isomorphic, as a graded algebra, to the Hochschild cohomology of the dg singularity…

Representation Theory · Mathematics 2020-09-10 Bernhard Keller

This paper is a continuation and a completion of [BoRo1]. We extend the Jordan decomposition of blocks: we show that blocks of finite groups of Lie type in non-describing characteristic are Morita equivalent to blocks of subgroups…

Representation Theory · Mathematics 2016-10-03 Cédric Bonnafé , Jean-François Dat , Raphaël Rouquier

We consider two categorifications of the cohomology of a topological space X by taking coefficients in the category of differential graded categories. We consider both derived global sections of a constant presheaf and singular cohomology…

Algebraic Topology · Mathematics 2019-07-16 Julian V. S. Holstein

We develop Tannaka duality theory for dg categories. To any dg functor from a dg category $\mathcal{A}$ to finite-dimensional complexes, we associate a dg coalgebra $C$ via a Hochschild homology construction. When the dg functor is…

K-Theory and Homology · Mathematics 2018-12-31 J. P. Pridham

This paper expands further on a category theoretical formulation of Hochschild cohomology for monoid objects in monoidal categories enriched over abelian groups, which has been studied in arXiv:1605.00842. This topic was also presented at…

Category Theory · Mathematics 2022-01-25 Magnus Hellstrøm-Finnsen

Two rings A and B are said to be derived Morita equivalent if their derived categories of modules are equivalent. By results of Rickard, if A and B are derived Morita equivalent algebras over a field k, then there is a complex of bimodules…

Rings and Algebras · Mathematics 2007-05-23 Amnon Yekutieli

In this paper we study the cohomology of the de Rham complex of sheaves of reflexive differential forms on a normal complex space. First, we prove that the complex is exact in degree one under suitable conditions on the underlying…

Algebraic Geometry · Mathematics 2014-01-30 Clemens Jörder

Reflexive homology is the homology theory associated to the reflexive crossed simplicial group; one of the fundamental crossed simplicial groups. It is the most general way to extend Hochschild homology to detect an order-reversing…

Algebraic Topology · Mathematics 2024-11-20 Daniel Graves

In this article, we present actions by central elements on Hochschild cohomology groups with arbitrary bimodule coefficients, as well as an interpretation of these actions in terms of exact sequences. Since our construction utilises the…

Rings and Algebras · Mathematics 2016-02-04 Reiner Hermann