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Let $\mathcal B$ be an extriangulated category with enough projectives and enough injectives. We define a proper $m$-term subcategory $\mathcal G$ on $\mathcal B$, which is an extriangulated subcategory. Then we give a correspondence…

Representation Theory · Mathematics 2020-12-15 Yu Liu , Panyue Zhou

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 paper, we give a complete classification of cotorsion pairs in a cluster category $\mathscr{C}$ of type $A^\infty_\infty$ via certain configurations of arcs, called $\tau$-compact Ptolemy diagrams, in an infinite strip with marked…

Representation Theory · Mathematics 2017-05-30 Huimin Chang , Yu Zhou , Bin Zhu

Given a hereditary complete cotorsion pair $(\mathsf A,\mathsf B)$ generated by a set of objects in a Grothendieck category $\mathsf K$, we construct a natural equivalence between the Becker coderived category of the left-hand class…

Category Theory · Mathematics 2025-10-14 Leonid Positselski

Let $\mathcal{A}$ be an abelian length category containing a $d$-cluster tilting subcategory $\mathcal{M}$. We prove that a subcategory of $\mathcal{M}$ is a $d$-torsion class if and only if it is closed under $d$-extensions and…

Representation Theory · Mathematics 2025-02-12 Jenny August , Johanne Haugland , Karin M. Jacobsen , Sondre Kvamme , Yann Palu , Hipolito Treffinger

For a finite dimensional algebra $A$, we establish correspondences between torsion classes and wide subcategories in $mod(A)$. In case $A$ is representation finite, we obtain an explicit bijection between these two classes of subcategories.…

Representation Theory · Mathematics 2017-06-19 Frederik Marks , Jan Stovicek

We show that a complete hereditary cotorsion pair $(\C,\C^\bot)$ in an exact category $\E$, together with a subcategory $\Z\subseteq\E$ containing $\C^\bot$, determines a Waldhausen category structure on the exact category $\C$, in which…

K-Theory and Homology · Mathematics 2020-06-16 Maru Sarazola

Given a finite category T, we consider the functor category [T,A], where A can in particular be any quasi-abelian category. Examples of quasi-abelian categories are given by any abelian category but also by non-exact additive categories as…

Category Theory · Mathematics 2024-03-20 Nadja Egner

We present the concept of cotorsion pairs cut along subcategories of an abelian category. This provides a generalization of complete cotorsion pairs, and represents a general framework to find approximations restricted to certain…

Category Theory · Mathematics 2022-08-02 Mindy Huerta , Octavio Mendoza , Marco A. Pérez

We prove that every Grothendieck topology induces a hereditary torsion pair in the category of presheaves of modules on a ringed site, and obtain a homological characterization of sheaves of modules: a presheaf of modules is a sheaf of…

Representation Theory · Mathematics 2025-07-30 Zhenxing Di , Liping Li , Li Liang

In this paper we describe a homotopy torsion theory in the category of small symmetric monoidal categories. Thanks to the use of natural isomorphisms as basis for the nullhomotopy structure, this homotopy torsion theory enjoys some…

Category Theory · Mathematics 2025-04-29 Mariano Messora

We present a quick approach to computing the $K$-theory of the category of locally compact modules over any order in a semisimple $\mathbb{Q}$-algebra. We obtain the $K$-theory by first quotienting out the compact modules and subsequently…

K-Theory and Homology · Mathematics 2020-06-22 Oliver Braunling , Ruben Henrard , Adam-Christiaan van Roosmalen

With a model of a geometric theory in an arbitrary topos, we associate a site obtained by endowing a category of generalized elements of the model with a Grothendieck topology, which we call the antecedent topology. Then we show that the…

Category Theory · Mathematics 2021-04-13 Olivia Caramello , Axel Osmond

This paper provides a preparatory introduction to torsors, written with a view toward later applications in the author's work. Rather than aiming at a comprehensive survey, the exposition focuses on those aspects of torsors that are most…

Group Theory · Mathematics 2026-03-13 Takao Inoué

T-convergence groups is a natural extension of lattice-valued topological groups, which is a newly introduced mathematical structure. In this paper, we will further explore the theory of T-convergence groups. The main results include: (1)…

Logic · Mathematics 2024-09-10 Lingqiang Li , Qiu Jin

A group element is called a generalized torsion if a finite product of its conjugates is equal to the identity. We prove that in a nilpotent or FC-group, the generalized torsion elements are all torsion elements. Moreover, we compute the…

Group Theory · Mathematics 2025-08-28 Raimundo Bastos , Csaba Schneider , Danilo Silveira

We resolve the Grothendieck-Serre question over an arbitrary base field $k$: for a smooth $k$-group scheme $G$ and a smooth $k$-variety $X$, we show that every generically trivial $G$-torsor over $X$ trivializes Zariski semilocally on $X$.…

Algebraic Geometry · Mathematics 2025-05-02 Alexis Bouthier , Kestutis Cesnavicius , Federico Scavia

A group element is called generalized torsion if a finite product of its conjugates is equal to the identity. We show that in a finitely generated abelian-by-finite group, an element is generalized torsion if and only if its image in the…

Group Theory · Mathematics 2025-12-09 Raimundo Bastos , Luis Mendonça

In a group, a non-trivial element is called a generalized torsion element if some non-empty finite product of its conjugates equals to the identity. We say that a knot has generalized torsion if its knot group admits such an element. For a…

Geometric Topology · Mathematics 2021-06-29 Kimihiko Motegi , Masakazu Teragaito

In this paper, our main focus is to explore different classes of nearly normally torsion-free ideals. We first characterize all finite simple connected graphs with nearly normally torsion-free cover ideals. Next, we characterize all…

Commutative Algebra · Mathematics 2022-06-02 Mehrdad Nasernejad , Ayesha Asloob Qureshi , Kazem Khashyarmanesh , Leslie G. Roberts