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We show that an abelian category can be exactly, fully faithfully embedded into a module category as the right perpendicular subcategory to a set of modules or module morphisms if and only if it is a locally presentable abelian category…

Category Theory · Mathematics 2022-09-14 Leonid Positselski

We explain why the naive definition of a natural exact category structure on complete, separated topological vector spaces with linear topology fails. In particular, contrary to arXiv:0711.2527, the category of such topological vector…

Category Theory · Mathematics 2024-05-16 Leonid Positselski

Semi-abelian and finitely cocomplete homological categories are characterized in terms of four resp. three simple axioms, in terms of the basic categorical notions introduced in the first few chapters of MacLane's classical book. As an…

Category Theory · Mathematics 2009-06-01 Manfred Hartl , Bruno Loiseau

We call a finitely complete category algebraically coherent when the change-of-base functors of its fibration of points are coherent, which means that they preserve finite limits and jointly strongly epimorphic pairs of arrows. We give…

Category Theory · Mathematics 2015-12-10 Alan S. Cigoli , James R. A. Gray , Tim Van der Linden

An algebraically exact category in one that admits all of the limits and colimits which every variety of algebras possesses and every forgetful functor between varieties preserves, and which verifies the same interactions between these…

Category Theory · Mathematics 2011-09-02 Richard Garner

In this note, we propose a generalisation of G. Janelidze's notion of an ideally exact category beyond the Barr exact setting. We define an ideally regular category as a regular, Bourn protomodular category with finite coproducts in which…

Category Theory · Mathematics 2026-03-03 Sandra Mantovani , Mariano Messora

We survey the basics of homological algebra in exact categories in the sense of Quillen. All diagram lemmas are proved directly from the axioms, notably the five lemma, the 3 x 3-lemma and the snake lemma. We briefly discuss exact functors,…

History and Overview · Mathematics 2009-04-22 Theo Buehler

Let $C$ be an additive category with cokernels and let Mod($C$) be the category of additive functors from $C^{op}$ to the category Ab of abelian groups. Let mod($C$) be the full subcategory of Mod($C$) consisting of coherent functors. In…

Category Theory · Mathematics 2020-12-16 Mohammad Khazaei , Reza Sazeedeh

In this paper, we classify certain subcategories of modules over a ring R. A wide subcategory of R-modules is an Abelian subcategory of R-Mod that is closed under extensions. We give a complete classification of wide subcategories of…

Rings and Algebras · Mathematics 2007-05-23 Mark Hovey

Let $\mathcal{M}$ be a small $n$-abelian category. We show that the category of absolutely pure group valued functors over $\mathcal{M}$, denote by $\mathcal{L}_2(\mathcal{M},\mathcal{G})$, is an abelian category and $\mathcal{M}$ is…

Representation Theory · Mathematics 2020-10-01 Ramin Ebrahimi , Alireza Nasr-Isfahani

We prove that the 2-category of skeletally small abelian categories with exact monoidal structures is anti-equivalent to the 2-category of fp-hom-closed definable additive categories satisfying an exactness criterion. For a fixed finitely…

Representation Theory · Mathematics 2020-10-26 Rose Wagstaffe

Consider an exact couple in a semiabelian category in the sense of Palamodov, i.e., in an additive category in which every morphism has a kernel as well as a cokernel and the induced morphism between coimage and image is always monic and…

Category Theory · Mathematics 2014-06-27 Yaroslav Kopylov , Sven-Ake Wegner

We show that every additive category with kernels and cokernels admits a maximal exact structure. Moreover, we discuss two examples of categories of the latter type arising from functional analysis.

Functional Analysis · Mathematics 2014-06-30 Dennis Sieg , Sven-Ake Wegner

In this paper we study categorical properties of the category of abelian hypergroups that leads to the notion of hyper (almost) preadditive and hyper (almost) abelian categories. Our goal is to create a path towards a general theory of…

Category Theory · Mathematics 2025-09-11 Kaique Matias de Andrade Roberto , Ana Luiza Tenório

Let $R$ be a commutative ring. A full additive subcategory $\C$ of $R$-modules is triangulated if whenever two terms of a short exact sequence belong to $\C$, then so does the third term. In this note we give a classification of…

Commutative Algebra · Mathematics 2009-12-03 Sunil K. Chebolu

We prove a general theorem which includes most notions of "exact completion". The theorem is that "k-ary exact categories" are a reflective sub-2-category of "k-ary sites", for any regular cardinal k. A k-ary exact category is an exact…

Category Theory · Mathematics 2012-09-06 Michael Shulman

We classify certain subcategories in quotients of exact categories. In particular, we classify the triangulated and thick subcategories of an algebraic triangulated category, i.e. the stable category of a Frobenius category.

Category Theory · Mathematics 2017-12-15 Emilie Arentz-Hansen

We investigate how to characterize subcategories of abelian categories in terms of intrinsic axioms. In particular, we find intrinsic axioms which characterize generating cogenerating functorially finite subcategories, precluster tilting…

Representation Theory · Mathematics 2021-08-09 Sondre Kvamme

We show that if A is an abelian category satisfying certain mild conditions, then one can introduce the concept of a moduli space of (semi)stable objects which has the structure of a projective algebraic variety. This idea is applied to…

Algebraic Geometry · Mathematics 2012-01-04 Vyacheslav Futorny , Marcos Jardim , Adriano Moura

We develop general foundations of topological algebra over a linearly topologized ring k in a format applicable to both formal schemes and analytic adic spaces. We are especially interested in determining exact closed tensor categories of…

Number Theory · Mathematics 2026-04-01 Francesco Baldassarri