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We give a simultaneous generalization of exact categories and triangulated categories, which is suitable for considering cotorsion pairs, and which we call extriangulated categories. Extension-closed, full subcategories of triangulated…

Category Theory · Mathematics 2019-04-29 Hiroyuki Nakaoka , Yann Palu

Among cocomplete categories, the locally presentable ones can be defined as those with a strong generator consisting of presentable objects. Assuming Vop{\v{e}}nka's Principle, we prove that a cocomplete category is locally presentable iff…

Category Theory · Mathematics 2020-12-04 J. Adámek , A. Brooke-Taylor , T. Campion , L. Positselski , J. Rosický

A number of categories is presented that are algebraically complete and cocomplete, i.e., every endofunctor has an initial algebra and a terminal coalgebra. For all finitary (and, more generally, all precontinuous) set functors the initial…

Logic in Computer Science · Computer Science 2021-05-21 Jiri Adamek

A number of categories is presented that are algebraically complete and cocomplete, i.e., every endofunctor has an initial algebra and a terminal coalgebra. For all finitary (and, more generally, all precontinuous) set functors the initial…

Category Theory · Mathematics 2023-06-22 Jiří Adámek

We prove that an abelian category equipped with an ample sequence of objects is equivalent to the quotient of the category of coherent modules over the corresponding algebra by the subcategory of finite-dimensional modules. In the…

Rings and Algebras · Mathematics 2007-05-23 Alexander Polishchuk

Exact categories are a natural generalisation of abelian categories and provide a fertile ground to develop relative homological algebra. In this paper, starting from a class of relative Gorenstein projective objects in an exact category…

Representation Theory · Mathematics 2026-02-27 Anastasios Slaftsos , Jorge Vitória

Motivated by some problems proposed by Cuadra and Simson related to flat objects in finitely accessible Grothendieck categories, we study flatness in the more general setting of finitely accessible additive categories. For such category…

Category Theory · Mathematics 2025-05-13 Manuel Cortés-Izurdiaga

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

Many definitions of weak and strict $\infty$-categories have been proposed. In this paper we present a definition for $\infty$-categories with strict associators, but which is otherwise fully weak. Our approach is based on the existing type…

Category Theory · Mathematics 2021-09-06 Eric Finster , Alex Rice , Jamie Vicary

For A a category with finite colimits, we show that the embedding of A into the category of arrows Arr(A) determined by the initial object is the completion of A under strong homotopy cokernels. The nullhomotopy structure of Arr(A) (needed…

Category Theory · Mathematics 2023-10-03 Enrico M. Vitale

To a big n-tilting object in a complete, cocomplete abelian category A with an injective cogenerator we assign a big n-cotilting object in a complete, cocomplete abelian category B with a projective generator, and vice versa. Then we…

Category Theory · Mathematics 2021-01-13 Leonid Positselski , Jan Stovicek

We identify two categories of locally compact objects on an exact category A. They correspond to the well-known constructions of the Beilinson category lim A and the Kato category k(A). We study their mutual relations and compare the two…

Category Theory · Mathematics 2010-06-07 Luigi Previdi

For a commutative noetherian ring A, we compare the support of a complex of A-modules with the support of its cohomology. This leads to a classification of all full subcategories of A-modules which are thick (that is, closed under taking…

Commutative Algebra · Mathematics 2007-05-23 Henning Krause

In a recent article Facchini and Finocchiaro considered a natural pretorsion theory in the category of preordered sets inducing a corresponding stable category. In the present work we propose an alternative construction of the stable…

Category Theory · Mathematics 2022-01-19 Francis Borceux , Federico Campanini , Marino Gran

The purpose of this article is to study the existence of Deligne's tensor product of abelian categories by comparing it with the well-known ten- sor product of finitely cocomplete categories. The main result states that the former exists…

Category Theory · Mathematics 2012-12-10 Ignacio Lopez Franco

In the previous article "Hearts of twin cotorsion pairs on exact categories", we introduced the notion of the heart for any cotorsion pair on an exact category with enough projectives and injectives, and showed that it is an abelian…

Representation Theory · Mathematics 2020-03-16 Yu Liu

Given an idempotent complete additive category, we show the there is an explicitly constructed topological space such that the lattice of exact substructures is anti-isomorphic to the lattice of closed subsets. In the special case that the…

Representation Theory · Mathematics 2026-02-02 Julia Sauter

We prove that an additive track category with strong coproducts is equivalent to the category of pseudomodels for the algebraic theory of $\nil_2$ groups. This generalizes the classical statement that the category of models for the…

Algebraic Topology · Mathematics 2009-12-24 Gérald Gaudens

Let $\mathcal{E}=(\mathcal{A},\mathcal{S})$ be an exact category with enough projectives $\mathcal{P}$. We introduce the notion of support $\tau$-tilting subcategories of $\mathcal{E}$. It is compatible with existing definitions of support…

Representation Theory · Mathematics 2024-01-30 Jixing Pan , Yaohua Zhang , Bin Zhu

In this expository article, we will give an efficient functorial proof of the equivalence of various characterisations of purity in a finitely accessible additive category $\mathcal C$. The complications of the proofs for specific choices…

Representation Theory · Mathematics 2023-04-25 Samuel Dean