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We classify, up to isomorphism and up to equivalence, involutions on graded-division finite-dimensional simple real (associative) algebras, when the grading group is abelian.

Rings and Algebras · Mathematics 2018-02-13 Yuri Bahturin , Mikhail Kochetov , Adrián Rodrigo-Escudero

We give a necessary and sufficient condition for a morphism between recollements of abelian categories to be an equivalence.

Category Theory · Mathematics 2007-05-23 Vincent Franjou , Teimuraz Pirashvili

We obtain, via the formalism of tensor actions, a complete classification of the localizing subcategories of the stable derived category of any affine scheme with hypersurface singularities and of any local complete intersection over a…

Algebraic Geometry · Mathematics 2014-03-19 Greg Stevenson

Torsion objects of von Neumann categories describe the phenomen "spectrum near zero" discovered by S. Novikov and M. Shubin. In this paper we classify Hermitian forms on torsion objects of a finite von Neumann category. We prove that any…

Differential Geometry · Mathematics 2007-05-23 Michael Farber

Starting from certain perverse sheaves on an abelian variety, including the intersection cohomology sheaves of curves and smooth ample divisors, we construct a semisimple super-Tannakian category.

Algebraic Geometry · Mathematics 2007-06-13 Rainer Weissauer

In this article we construct various models for singularity categories of modules over differential graded rings. The main technique is the connection between abelian model structures, cotorsion pairs and deconstructible classes, and our…

Category Theory · Mathematics 2012-05-22 Hanno Becker

We introduce the concept of a pseudo-cluster tilting subcategory from the viewpoint of the fact that the quotient of an exact category by a cluster tilting subcategory is an abelian category. We prove that the quotients in the case of…

Representation Theory · Mathematics 2023-03-14 Jie Xu , Yuefei Zheng

We classify, up to isomorphism, gradings by abelian groups on nilpotent filiform Lie algebras of nonzero rank. In case of rank 0, we describe conditions to obtain non trivial $\Z_k$-gradings.

Rings and Algebras · Mathematics 2013-08-13 Yuri Bahturin , Michel Goze , Elisabeth Remm

Let $\mathcal A$ be a Hom-finite abelian category with enough projectives. In this note, we show that any covariantly finite $\tau$-rigid subcategory is contained in a support $\tau$-tilting subcategory. We also show that support…

Representation Theory · Mathematics 2023-02-07 Yu Liu , Panyue Zhou

Recently Dupont proved that the categories of discrete and codiscrete (or connected) objects in an abelian 2-category are equivalent abelian categories. He posses also a question whether any abelian category comes in this way. We will give…

Category Theory · Mathematics 2008-09-26 Teimuraz Pirashvili

Torsion pairs in the category of finitely presented modules over a noetherian ring can be parametrised by the class of cosilting modules. In this paper, we characterise such modules in terms of their indecomposable summands, providing a new…

Representation Theory · Mathematics 2019-11-07 Karin Baur , Rosanna Laking

We consider an arbitrary Abelian category $\mathcal{A}$ and a subcategory $\mathcal{T}$ closed under extensions and direct summands, and characterize those $\mathcal{T}$ that are (semi-)special preenveloping in $\mathcal{A}$; as a…

Representation Theory · Mathematics 2021-12-28 Carlos E. Parra , Manuel Saorín , Simone Virili

Let $U$ be a smooth and connected curve over an algebraically closed field of positive characteristic, with smooth compactification $X$. We generalize classical Geometric Class Field theory to provide a classification of fppf $G$-torsors…

Algebraic Geometry · Mathematics 2026-03-20 Bryden Cais , Shusuke Otabe

This is mostly an overview. Given finitely presentable abelian categories $A$ and $B$, we sketch the construction of an abelian category of continuous functors from $A$ to $B$ that has nice $2$-categorical behaviour and gives an explicit…

Category Theory · Mathematics 2022-05-18 D. Kaledin

Every Serre subcategory of an abelian category is assigned a unique type. The type of a Serre subcategory of a Grothendieck category is in the list: $$(0, 0), \ (0, -1), \ (1, -1), \ (0, -2), \ (1, -2), \ (2, -1), \ (+\infty, -\infty);$$…

Category Theory · Mathematics 2017-05-10 Jian Feng , Pu Zhang

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

We give a complete classification of torsion pairs in repetitive cluster categories of type $A_n$, which were defined by Zhu as the orbit categories, via certain configurations of diagonals, called Ptolemy diagrams. As applications, we…

Representation Theory · Mathematics 2023-11-21 Huimin Chang

This paper is devoted to the more elementary aspects of the contramodule story, and can be viewed as an extended introduction to the more technically complicated arXiv:1503.05523. Reduced cotorsion abelian groups form an abelian category,…

Category Theory · Mathematics 2020-01-03 Leonid Positselski

It is a well established fact that the notions of quasi-abelian categories and tilting torsion pairs are equivalent. This equivalence fits in a wider picture including tilting pairs of $t$-structures. Firstly, we extend this picture into a…

Representation Theory · Mathematics 2020-01-01 Luisa Fiorot

To study the set of torsion classes of a finite dimensional basic algebra, we use a decomposition, called sign-decomposition, parametrized by elements of $\{\pm1\}^n$ where $n$ is the number of simple modules. If $A$ is an algebra with…

Representation Theory · Mathematics 2019-09-16 Toshitaka Aoki