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We consider a finite dimensional strongly $G$-graded algebra $A$ with { self-injective} $1$-component $B$, and in our main result we prove that the induction from $B$ to $A$ of a basic support $\tau$-tilting pair of $B$-modules is a support…

Representation Theory · Mathematics 2022-11-17 Simion Breaz , Andrei Marcus , George Ciprian Modoi

Enomoto and Sakai classified IE-closed subcategories over hereditary algebras via twin rigid modules. However, this classification inherently relies on the vanishing of second extension spaces, thus failing for arbitrary finite-dimensional…

Representation Theory · Mathematics 2026-04-03 Hanpeng Gao , Dajun Liu , Yu-Zhe Liu

We classify up to coarse equivalence all countable abelian groups of finite torsion free rank. The Q-cohomological dimension and the torsion free rank are the two invariants that give us such classification. We also prove that any countable…

Group Theory · Mathematics 2008-03-05 J. Higes

We introduce a notion of total acyclicity associated to a subcategory of an abelian category and consider the Gorenstein objects they define. These Gorenstein objects form a Frobenius category, whose induced stable category is equivalent to…

Rings and Algebras · Mathematics 2019-09-13 Lars Winther Christensen , Sergio Estrada , Peder Thompson

In this paper, we classify several subcategories of the category of coherent sheaves on a noetherian divisorial scheme (e.g. a quasi-projective scheme over a commutative noetherian ring). More precisely, we classify the torsionfree (resp.…

Representation Theory · Mathematics 2023-04-21 Shunya Saito

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 the class of reduced Abelian torsion-free groups $G$ of finite rank, we describe TI-groups, this means that every associative ring on $G$ is filial. If every associative multiplication on $G$ is the zero multiplication, then $G$ is…

Rings and Algebras · Mathematics 2021-05-25 Ekaterina Kompantseva , Askar Tuganbaev

Given a weight-one element $u$ of a vertex operator algebra $V$, we construct an automorphism of the category of generalized $g$-twisted modules for automorphisms $g$ of $V$ fixing $u$. We apply this construction to the case that $V$ is an…

Quantum Algebra · Mathematics 2022-11-11 Yi-Zhi Huang , Christopher Sadowski

We prove that for a countable, commutative ring $R$, the class of countable $R$-modules either has only countably many isomorphism types, or else it is Borel complete. The machinery gives a succinct proof of the Borel completeness of TFAB,…

Logic · Mathematics 2022-09-16 Michael C. Laskowski , Danielle S. Ulrich

We classify all tilting classes over an arbitrary commutative ring via certain sequences of Thomason subsets of the spectrum, generalizing the classification for noetherian commutative rings by…

Commutative Algebra · Mathematics 2020-03-24 Michal Hrbek , Jan Šťovíček

We define an integer-valued invariant of special cube complexes called the genus, and prove that having genus one characterizes special cube complexes with abelian fundamental group. Using the genus, we obtain a new proof that the…

Geometric Topology · Mathematics 2016-12-30 Corey Bregman

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

We study categories of dualizable torsion and complete objects for compactly-rigidly generated tensor-triangulated categories T with a Noetherian central action of a graded commutative Noetherian ring R. We show that they always admit a…

Category Theory · Mathematics 2025-12-05 Jun Maillard , Jan Šťovíček

We show that the category of finite-dimensional modules over the endomorphism algebra of a rigid object in a Hom-finite triangulated category is equivalent to the Gabriel-Zisman localisation of the category with respect to a certain class…

Representation Theory · Mathematics 2020-12-21 Aslak Bakke Buan , Bethany Marsh

We provide an explicit classification of all simple $\mathfrak{sl}_2$-modules that are torsion free of rank $1$ over the Cartan subalgebra. We also establish a similar result for the first Weyl algebra and for the Lie superalgebra…

Representation Theory · Mathematics 2026-03-05 Dimitar Grantcharov , Libor Krizka , Volodymyr Mazorchuk

We give an account of model theory in the context of compactly generated triangulated and tensor-triangulated categories ${\cal T}$. We describe pp formulas, pp-types and free realisations in such categories and we prove elimination of…

Representation Theory · Mathematics 2024-05-01 Mike Prest , Rose Wagstaffe

We analyze the algebraic structures of G--Frobenius algebras which are the algebras associated to global group quotient objects. Here G is any finite group. These algebras turn out to be modules over the Drinfeld double of the group ring…

Algebraic Geometry · Mathematics 2007-05-23 Ralph M. Kaufmann

To define the notion of a generic property of finite dimensional 2-step nilpotent Lie algebras we use standard correspondence between such Lie algebras and points of an appropriate algebraic variety, where a negligible set is one contained…

Rings and Algebras · Mathematics 2014-08-06 Maria V. Milentyeva

We develop silting theory of a noetherian algebra $\Lambda$ over a commutative noetherian ring $R$. We study mutation theory of $2$-term silting complexes of $\Lambda$, and as a consequence, we see that mutation exists. As in the case of…

Representation Theory · Mathematics 2022-02-17 Yuta Kimura

Many bundle gerbes constructed in practice are either infinite-dimensional, or finite-dimensional but built using submersions that are far from being fibre bundles. Murray and Stevenson proved that gerbes on simply-connected manifolds,…

Differential Geometry · Mathematics 2021-09-24 David Michael Roberts
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