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Tensor products usually have nonzero torsion. This is a central theme of Auslander's paper "Modules over unramified regular local rings"; the theme continues in the work of Huneke and Wiegand. The main focus in this note is on tensor powers…

Commutative Algebra · Mathematics 2014-12-22 Olgur Celikbas , Srikanth B. Iyengar , Greg Piepmeyer , Roger Wiegand

In this article, gentle algebras are realised as tiling algebras, which are associated to partial triangulations of unpunctured surfaces with marked points on the boundary. This notion of tiling algebras generalise the notion of Jacobian…

Representation Theory · Mathematics 2018-03-16 Karin Baur , Raquel Coelho Simoes

We classify Jordan $G$-tori, where $G$ is any torsion-free abelian group. Using the Zelmanov prime structure theorem, such a class divides into three types, namely, {the Hermitian type, the Clifford type and the Albert type.} We concretely…

Quantum Algebra · Mathematics 2013-12-09 Saeid Azam , Yoji Yoshii , Malihe Yousofzadeh

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

The dimension of any module over an algebra of affiliated operators ${\mathcal U}$ of a finite von Neumann algebra ${\mathcal A}$ is defined using a trace on ${\mathcal A}.$ All zero-dimensional ${\mathcal U}$-modules constitute the torsion…

Rings and Algebras · Mathematics 2010-09-14 Lia Vas

The aim of this paper is to unify classification theories of torsion classes of finite dimensional algebras and commutative Noetherian rings. For a commutative Noetherian ring $R$ and a module-finite $R$-algebra $\Lambda$, we study the set…

Representation Theory · Mathematics 2023-05-30 Osamu Iyama , Yuta Kimura

We put cluster tilting in ageneral framework by showing that any quotient of a triangulated category modulo a tilting subcategory (that is, a maximal one-orthogonal subcategory) carries an abelian structure. These abelian quotients turn out…

Representation Theory · Mathematics 2007-06-13 Steffen Koenig , Bin Zhu

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

Mutation of compact silting objects is a fundamental operation in the representation theory of finite-dimensional algebras due to its connections to cluster theory and to the lattice of torsion pairs in module or derived categories. In this…

Representation Theory · Mathematics 2025-06-18 Lidia Angeleri Hügel , Rosanna Laking , Jan Šťovíček , Jorge Vitória

The Resolution Theorem for Compact Abelian Groups is applied to show that the profinite subgroups of a finite-dimensional compact connected abelian group (protorus) which induce tori quotients comprise a lattice under intersection (meet)…

Group Theory · Mathematics 2025-03-28 Wayne Lewis

We study the classes of modules which are generated by a silting module. In the case of either hereditary or perfect rings it is proved that these are exactly the torsion $\mathcal{T}$ such that the regular module has a special…

Representation Theory · Mathematics 2017-04-06 Simion Breaz , Jan Žemlička

In this paper, we discuss certain circumstances in which the category of tame functors inherits an abelian category structure with minimal resolutions and a model category structure with minimal cofibrant replacements. We also present a…

Algebraic Topology · Mathematics 2024-03-26 Wojciech Chachólski , Barbara Giunti , Claudia Landi , Francesca Tombari

We prove that the Borel space of torsion-free Abelian groups with domain $\omega$ is Borel complete, i.e., the isomorphism relation on this Borel space is as complicated as possible, as an isomorphism relation. This solves a long-standing…

Logic · Mathematics 2023-02-22 Gianluca Paolini , Saharon Shelah

We mainly investigate abelian quotients of the categories of short exact sequences. The natural framework to consider the question is via identifying quotients of morphism categories as modules categories. These ideas not only can be used…

Representation Theory · Mathematics 2018-02-13 Zengqiang Lin

In a perfect category every object has a minimal projective resolution. We give a criterion for the category of modules over a categorygraded algebra to be perfect.

Category Theory · Mathematics 2016-02-09 Ana Paula Santana , Ivan Yudin

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 construct certain tensor categories that are dominated by finitely many simple objects. Objects in these categories are modules over rings of algebra integers. We show how to obtain TQFTs defined over algebra integers from these…

Quantum Algebra · Mathematics 2007-05-23 Qi Chen

This paper classifies spherical objects in various geometric settings in dimensions two and three, including both minimal and partial crepant resolutions of Kleinian singularities, as well as arbitrary flopping 3-fold contractions with only…

Algebraic Geometry · Mathematics 2024-09-13 Wahei Hara , Michael Wemyss

For the module category of an Artin algebra, we generalize the notion of torsion pairs to ideal torsion pairs. Instead of full subcategories of modules, ideals of morphisms of the ambient category are considered. We characterize the…

Representation Theory · Mathematics 2026-02-25 Kevin Schlegel

We present an elementary proof of the fact that every torsor for an affine group scheme over an algebraically closed field is trivial. This is related to the uniqueness of fibre functors on neutral tannakian categories.

Algebraic Geometry · Mathematics 2022-03-31 Michael Wibmer