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We outline a definition of accessible and presentable objects in a 2-category $\mathcal K$ endowed with a "KZ context", that is to say a pair of lax-idempotent monads interacting in a prescribed way; this perspective suggests a unified…

Category Theory · Mathematics 2025-08-05 Ivan Di Liberti , Fosco Loregian

We define the notion of a $\lambda$-definable category, a generalisation of the notion of definable category from the model theory of modules. Let ${\cal C}$ be a $\lambda$-accessible additive category. We characterise the additive functors…

Representation Theory · Mathematics 2025-01-08 Samuel Dean

We propose a framework for producing interesting subcategories of the category ${}_A\mathsf{Mod}$ of left $A$-modules, where $A$ is an associative algebra over a field $k$. The construction is based on the composition, $Y$, of the Yoneda…

Representation Theory · Mathematics 2025-07-18 Dylan Fillmore , Jonas T. Hartwig

In this paper we show that how the representation theory of subcategories (of the category of modules over an Artin algebra) can be connected to the representation theory of all modules over some algebra. The subcategories dealing with are…

Representation Theory · Mathematics 2020-11-03 Rasool Hafezi

Let $(\mathscr{C},\mathbb{E},\mathfrak{s})$ be an ${\rm Ext}$-finite, Krull-Schmidt and $k$-linear $n$-exangulated category with $k$ a commutative artinian ring. In this note, we define two additive subcategories $\mathscr{C}_r$ and…

Representation Theory · Mathematics 2021-11-15 Jian He , Jing He , Panyue Zhou

We introduce the notion of the $\infty$-category of (complete) derived $G$-graded modules over a $G$-graded ring $R$ for a torsion-free abelian group $G$, and we study its foundational properties. Moreover, we prove a categorical…

Commutative Algebra · Mathematics 2026-04-06 Ryo Ishizuka , Shou Yoshikawa

Let $\mathcal {C}$ be a small category and let $R$ be a representation of the category $\mathcal {C}$, that is, a pseudofunctor from a small category to the category of small preadditive categories. In this paper, we mainly study the…

Representation Theory · Mathematics 2026-05-29 Mawei Wu

Let A be a commutative noetherian ring. In this paper, we interpret localizing subcategories of the derived category of A by using subsets of Spec A and subcategories of the category of A-modules. We unify theorems of Gabriel, Neeman and…

Commutative Algebra · Mathematics 2009-07-15 Ryo Takahashi

We introduce the notions of a $\mathbf{D}$-standard abelian category and a $\mathbf{K}$-standard additive category. We prove that for a finite dimensional algebra $A$, its module category is $\mathbf{D}$-standard if and only if any derived…

Representation Theory · Mathematics 2018-10-02 Xiao-Wu Chen , Yu Ye

We study and relate categories of modules, comodules and contramodules over a representation of a small category taking values in (co)algebras, in a manner similar to modules over a ringed space. As a result, we obtain a categorical…

Rings and Algebras · Mathematics 2023-02-15 Mamta Balodi , Abhishek Banerjee , Samarpita Ray

We prove the following instance of a conjecture stated in arXiv:1103.4770. Let $G$ be an abelian semialgebraic group over a real closed field $R$ and let $X$ be a semialgebraic subset of $G$. Then the group generated by $X$ contains a…

Logic · Mathematics 2019-09-26 Elías Baro , Pantelis E. Eleftheriou , Ya'acov Peterzil

Connections between heaps of modules and (affine) modules over rings are explored. This leads to explicit, often constructive, descriptions of some categorical constructions and properties that are implicit in universal algebra and…

Rings and Algebras · Mathematics 2025-10-08 Simion Breaz , Tomasz Brzezinski , Bernard Rybolowicz , Paolo Saracco

A differential module is a module equipped with a square-zero endomorphism. This structure underpins complexes of modules over rings, as well as differential graded modules over graded rings. We establish lower bounds on the class--a…

Commutative Algebra · Mathematics 2009-11-11 Luchezar L. Avramov , Ragnar-Olaf Buchweitz , Srikanth Iyengar

The homotopy category of complexes of projective left-modules over any reasonably nice ring is proved to be a compactly generated triangulated category, and a duality is given between its subcategory of compact objects and the finite…

Rings and Algebras · Mathematics 2007-05-23 Peter Jorgensen

For a finite group scheme G over an algebraically closed field k of characteristic p>0 we study G-modules M, which are defined in terms of properties of their pull-backs along p-points of G. We show that the corresponding subcategories…

Representation Theory · Mathematics 2011-10-13 Rolf Farnsteiner

We classify the module categories over the double (possibly twisted) of a finite group.

Quantum Algebra · Mathematics 2007-05-23 Victor Ostrik

We introduce the notion of mutation of $n$-cluster tilting subcategories in a triangulated category with Auslander-Reiten-Serre duality. Using this idea, we are able to obtain the complete classifications of rigid Cohen-Macaulay modules…

Representation Theory · Mathematics 2015-06-26 Osamu Iyama , Yuji Yoshino

This article contains a review of categorifications of semisimple representations of various rings via abelian categories and exact endofunctors on them. A simple definition of an abelian categorification is presented and illustrated with…

Representation Theory · Mathematics 2007-05-23 Mikhail Khovanov , Volodymyr Mazorchuk , Catharina Stroppel

For a left coherent ring A with every left ideal having a countable set of generators, we show that the coderived category of left A-modules is compactly generated by the bounded derived category of finitely presented left A-modules…

Category Theory · Mathematics 2017-03-21 Leonid Positselski

The definition of a pseudo-dualizing complex is obtained from that of a dualizing complex by dropping the injective dimension condition, while retaining the finite generatedness and homothety isomorphism conditions. In the specific setting…

Category Theory · Mathematics 2025-11-10 Leonid Positselski