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We construct an "almost involution" assigning a new DG-category to a given one, and use this construction to recover, say, the abelian category of graded modules over the graded ring $R^*$ from the DG-category of DG-modules over a DG-ring…

Category Theory · Mathematics 2025-10-08 Leonid Positselski

We give a classification of all exact structures on a given idempotent complete additive category. Using this, we investigate the structure of an exact category with finitely many indecomposables. We show that the relation of the…

Representation Theory · Mathematics 2019-07-30 Haruhisa Enomoto

We prove that the derived categories of abelian categories have unique enhancements -- all of them, the unbounded, bounded, bounded above and bounded below derived categories. The unseparated and left completed derived categories of a…

Algebraic Geometry · Mathematics 2021-01-13 Alberto Canonaco , Amnon Neeman , Paolo Stellari

We introduce the notion of a "category with path objects", as a slight strengthening of Kenneth Brown's classic notion of a "category of fibrant objects". We develop the basic properties of such a category and its associated homotopy…

Category Theory · Mathematics 2017-06-21 Benno van den Berg , Ieke Moerdijk

We introduce a model category of spaces based on the definable sets of an o-minimal expansion of a real closed field. As a model category, it resembles the category of topological spaces, but its underlying category is a coherent topos. We…

Algebraic Topology · Mathematics 2021-08-27 Reid Barton , Johan Commelin

We study when the stable category of an abelian category modulo a full additive subcategory is balanced and, in case the subcategory is functorially finite, we study a weak version of balance. Precise necessary and sufficient conditions are…

Category Theory · Mathematics 2010-10-05 Pedro Nicolas , Manuel Saorin

A coextensive category can be defined as a category $\mathcal{C}$ with finite products such that for each pair $X,Y$ of objects in $\mathcal{C}$, the canonical functor $\times\colon X/\mathcal{C} \times Y/\mathcal{C} \to (X \times…

Category Theory · Mathematics 2020-08-11 David Neal Broodryk

We give an elementary construction of the exact completion of a weakly lex category for categories enriched in the cartesian closed category $\mathsf{Pos}$ of partially ordered sets. Paralleling the ordinary case, we characterize categories…

Category Theory · Mathematics 2025-12-16 Vasileios Aravantinos-Sotiropoulos

We define the notion of exact completion with respect to an existential elementary doctrine. We observe that the forgetful functor from the 2-category exact categories to existential elementary doctrines has a left biadjoint that can be…

Category Theory · Mathematics 2012-12-06 Maria Emilia Maietti , Giuseppe Rosolini

For a category $\mathcal E$ with finite limits and well-behaved countable coproducts, we construct a model structure, called the effective model structure, on the category of simplicial objects in $\mathcal E$, generalising the Kan--Quillen…

Category Theory · Mathematics 2022-11-11 Nicola Gambino , Simon Henry , Christian Sattler , Karol Szumiło

Categories of partial functions have become increasingly important principally because of their applications in theoretical computer science. In this note we prove that the category of partial bijections between sets as an…

Discrete Mathematics · Computer Science 2009-03-06 Emil Schwab

We develop a homotopy theory for additive categories endowed with endofunctors, analogous to the concept of a model structure. We use it to construct the homotopy theory of a Hovey triple (which consists of two compatible complete cotorsion…

Representation Theory · Mathematics 2017-03-09 Zhi-Wei Li

A coextensive category can be defined as a category $\mathcal{C}$ with finite products such that for each pair $X,Y$ of objects in $\mathcal{C}$, the canonical functor $\times\colon X/\mathcal{C} \times Y/\mathcal{C} \to (X \times…

Category Theory · Mathematics 2021-04-27 David Neal Broodryk

Adhesive categories are categories which have pushouts with one leg a monomorphism, all pullbacks, and certain exactness conditions relating these pushouts and pullbacks. We give a new proof of the fact that every topos is adhesive. We also…

Category Theory · Mathematics 2011-04-14 Stephen Lack

Extriangulated categories axiomatize extension-closed subcategories of triangulated categories. We show that the homotopy category of an exact quasi-category can be equipped with a natural extriangulated structure.

Category Theory · Mathematics 2020-04-07 Hiroyuki Nakaoka , Yann Palu

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 generalize the definition of an exact sequence of tensor categories due to Brugui\`eres and Natale, and introduce a new notion of an exact sequence of (finite) tensor categories with respect to a module category. We give three…

Quantum Algebra · Mathematics 2015-04-07 Pavel Etingof , Shlomo Gelaki

Rump has recently showed the existence of a unique maximal Quillen exact structure on any additive category. We study when this is given by the stable short exact sequences, i.e. kernel-cokernel pairs consisting of a semi-stable kernel and…

Category Theory · Mathematics 2019-07-02 Septimiu Crivei

Building on previous work, we study the splitting of idempotents in the category of extensions $\mathbb{E}\operatorname{-Ext}(\mathcal{C})$ associated to a pair $(\mathcal{C},\mathbb{E})$ of an additive category and a biadditive functor to…

Category Theory · Mathematics 2023-10-27 Raphael Bennett-Tennenhaus , Johanne Haugland , Mads Hustad Sandøy , Amit Shah

We prove Steinebrunner's conjecture on the biequivalence between (colored) properads and labelled cospan categories. The main part of the work is to establish a 1-categorical, strict version of the conjecture, showing that the category of…

Category Theory · Mathematics 2023-08-21 Jonathan Beardsley , Philip Hackney