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We introduce and develop the notion of *displayed categories*. A displayed category over a category C is equivalent to "a category D and functor F : D --> C", but instead of having a single collection of "objects of D" with a map to the…

Category Theory · Mathematics 2023-06-22 Benedikt Ahrens , Peter LeFanu Lumsdaine

In this paper, we extend the notion of modular functor and fusion category to what we called $G$ equivariant modular functor and $G$ equivariant fusion category, where $G$ is a finite group, and establish a correspondence between between…

Quantum Algebra · Mathematics 2008-07-08 Alexander Kirillov , Tanvir Prince

The Gorenstein property in local algebra admits several characterizations via its module category. The goal of this paper is to collect and generalize such characterizations to the relative setting, i.e., to Gorenstein morphisms as defined…

Commutative Algebra · Mathematics 2025-02-25 Andrew Soto Levins , Prashanth Sridhar

We define exact functors from categories of Harish-Chandra modules for certain real classical groups to finite-dimensional modules over an associated graded affine Hecke algebra with parameters. We then study some of the basic properties of…

Representation Theory · Mathematics 2009-06-15 Dan Ciubotaru , Peter E. Trapa

We define locally wide finitary 2-categories by relaxing the definition of finitary 2-categories to allow infinitely many objects and isomorphism classes of 1-morphisms and infinite dimensional hom-spaces of 2-morphisms. After defining…

Category Theory · Mathematics 2021-06-24 James Macpherson

Let $\CC^0_{\g}$ be the category of finite-dimensional integrable modules over the quantum affine algebra $U_{q}'(\g)$ and let $R^{A_\infty}\gmod$ denote the category of finite-dimensional graded modules over the quiver Hecke algebra of…

Representation Theory · Mathematics 2017-05-17 Seok-Jin Kang , Masaki Kashiwara , Myungho Kim , Se-jin Oh

Let $k$ be a commutative ring, let $\mathcal{C}$ be a small, $k$-linear, Hom-finite, locally bounded category, and let $\mathcal{B}$ be a $k$-linear abelian category. We construct a Frobenius exact subcategory…

Category Theory · Mathematics 2019-01-17 Sondre Kvamme

Let $A$, $B$ and $C$ be associative rings with identity. Using a result of Koenig we show that if we have a $\mathbb{D}^{{\rm{b}}}({\rm{{mod\mbox{-}}}} )$ level recollement, writing $A$ in terms of $B$ and $C$, then we get a…

Representation Theory · Mathematics 2014-07-11 Javad Asadollahi , Rasool Hafezi , Razieh Vahed

Let $\mathcal{X}$ be a skeletally small additive category. Using the canonical equivalence between two different presentations of the free abelian category over $\mathcal{X}$, we give a new and simple characterization of definable…

Category Theory · Mathematics 2024-11-12 Ramin Ebrahimi

The representations of a quiver Q over a field k have been studied for a long time. It seems to be worthwhile to consider also representations of Q over arbitrary finite-dimensional k-algebras A. Here we draw the attention to the case when…

Representation Theory · Mathematics 2013-12-31 Claus Michael Ringel , Pu Zhang

We classify localising subcategories of the stable module category of a finite group that are closed under tensor product with simple (or, equivalently all) modules. One application is a proof of the telescope conjecture in this context.…

Representation Theory · Mathematics 2011-04-18 Dave Benson , Srikanth B. Iyengar , Henning Krause

We give a geometric realization of module categories of type $\tilde{A}_n$. We work with oriented arcs to define a translation quiver isomorphic to the Auslander-Reiten quiver of the module category of type $\tilde{A}_n$. To get a…

Representation Theory · Mathematics 2015-02-24 Karin Baur , Hermund André Torkildsen

Let $\mathcal{X}$ be a resolving and contravariantly finite subcategory of $\rm{mod}\mbox{-}\Lambda$, the category of finitely generated right $\Lambda$-modules. We associate to $\mathcal{X}$ the subcategory…

Representation Theory · Mathematics 2019-10-10 Rasool Hafezi , Intan Muchtadi-Alamsyah

We show that bounded type implies finite type for a constructible subcategory of the module category of a finitely generated algebra over a field, which is a variant of the first Brauer-Thrall conjecture. A full subcategory is constructible…

Representation Theory · Mathematics 2025-07-31 Kevin Schlegel , Andres Fernandez Herrero

We systematically apply semisimplification functors in modular representation theory. Motivated by the Duflo--Serganova functor in Lie superalgebras, we construct various functors of interest. In the setting of finite groups, we refine the…

Representation Theory · Mathematics 2025-09-12 Chris Hone , Finn Klein , Bregje Pauwels , Alexander Sherman , Oded Yacobi , Victor L. Zhang

Let $H$ be a Hopf algebra over a field $k$, and $A$ an $H$-comodule algebra. The categories of comodules and relative Hopf modules are then Grothendieck categories with enough injectives. We study the derived functors of the associated Hom…

Rings and Algebras · Mathematics 2007-05-23 S. Caenepeel , T. Guédénon

We show that differential calculus (in its usual form, or in the general form of topological differential calculus) can be fully imdedded into a functor category (functors from a small category of anchord tangent algebras to anchored sets).…

Algebraic Geometry · Mathematics 2021-03-25 Wolfgang Bertram , Jérémy Haut

We develop the theory of module categories over a Grothendieck-Verdier category, i.e. a monoidal category with a dualizing object and hence a duality structure more general than rigidity. Such a category C comes with two monoidal structures…

Category Theory · Mathematics 2024-06-03 Jürgen Fuchs , Gregor Schaumann , Christoph Schweigert , Simon Wood

In this paper we propose an approach to homotopical algebra where the basic ingredient is a category with two classes of distinguished morphisms: strong and weak equivalences. These data determine the cofibrant objects by an extension…

Algebraic Topology · Mathematics 2008-09-18 F. Guillen Santos , V. Navarro , P. Pascual , Agusti Roig

Let $R$, $S$ be two rings, $C$ an $R$-coring and ${}_{R}^C{\mathcal M}$ the category of left $C$-comodules. The category ${\bf Rep}\, ( {}_{R}^C{\mathcal M}, {}_{S}{\mathcal M} )$ of all representable functors ${}_{R}^C{\mathcal M} \to…

Rings and Algebras · Mathematics 2015-03-17 Gigel Militaru