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Given a $1$-tilting cotorsion pair over a commutative ring, we characterise the rings over which the $1$-tilting class is an enveloping class. To do so, we consider the faithful finitely generated Gabriel topology $\mathcal{G}$ associated…

Commutative Algebra · Mathematics 2020-03-19 Silvana Bazzoni , Giovanna Le Gros

Let $C$ be an additive category with cokernels and let Mod($C$) be the category of additive functors from $C^{op}$ to the category Ab of abelian groups. Let mod($C$) be the full subcategory of Mod($C$) consisting of coherent functors. In…

Category Theory · Mathematics 2020-12-16 Mohammad Khazaei , Reza Sazeedeh

The aim of this note is to outline the structure of the category of the Gorenstein projective modules for a Nakayama algebra. We are going to introduce the resolution quiver of such an algebra. It provides a fast algorithm in order to…

Representation Theory · Mathematics 2013-04-16 Claus Michael Ringel

In the first part of this paper, we prove the existence of torsion free covers in the category of representations of quivers, $(Q,R-Mod)$, for a wide class of quivers included in the class of the so-called source injective representation…

Category Theory · Mathematics 2010-09-02 Sergio Estrada , Salahattin Özdemir

We prove that for any finite-dimensional differential graded algebra with separable semisimple part the category of perfect modules is equivalent to a full subcategory of the category of perfect complexes on a smooth projective scheme with…

Algebraic Geometry · Mathematics 2020-03-18 Dmitri Orlov

The purpose of this paper is to suggest the construction and study properties of semi-infinite induction, which relates to semi-infinite cohomology the same way induction relates to homology and coinduction to cohomology. We prove a version…

q-alg · Mathematics 2008-02-03 Alexander A. Voronov

We classify all tilting and cotilting classes over commutative noetherian rings in terms of descending sequences of specialization closed subsets of the Zariski spectrum. Consequently, all resolving subcategories of finitely generated…

Commutative Algebra · Mathematics 2014-06-03 Lidia Angeleri Hügel , David Pospisil , Jan Stovicek , Jan Trlifaj

We classify the simple infinite dimensional integrable modules with finite dimensional weight spaces over the quantized enveloping algebra of an untwisted affine algebra. We prove that these are either highest (lowest) weight integrable…

Quantum Algebra · Mathematics 2007-05-23 Vyjayanthi Chari , Jacob Greenstein

In this paper we improve recent results dealing with cellular covers of $R$-modules. Cellular covers (sometimes called co-localizations) come up in the context of homotopical localization of topological spaces. They are related to…

Group Theory · Mathematics 2009-10-28 Rüdiger Göbel , José L. Rodríguez , Lutz Strüngmann

We study infinite dimensional tilting modules over a concealed canonical algebra of domestic or tubular type. In the domestic case, such tilting modules are constructed by using the technique of universal localization, and they can be…

Representation Theory · Mathematics 2019-11-07 Lidia Angeleri Hügel , Dirk Kussin

Let $R$ be a commutative ring. An $R$-module $M$ is said to be almost projective if ${\rm Ext}^1_R(M, N) = 0$ for any $R_{\mathfrak{m}}$-module $N$ and any maximal ideal $\mathfrak{m}$ of $R$. In this paper, we investigate rings $R$ over…

Commutative Algebra · Mathematics 2024-06-05 Xiaolei Zhang , Wei Qi , Dechuan Zhou

In contrast to the theory of tilting modules, the dual theory lacks a unified definition. Nevertheless, several notions of cotilting modules have been proposed. In this paper, we compare four of the main definitions of cotilting modules…

Representation Theory · Mathematics 2025-12-23 Kamran Divaani-Aazar , Ali Mahin Fallah , Massoud Tousi

Let $\text{Red}(M)$ be the sum of all reduced submodules of a module $M$. For modules over commutative rings, $\text{Soc}(M)\subseteq \text{Red}(M)$. By drawing motivation from how $\text{Soc}$-injective modules were defined by Amin et. al.…

Commutative Algebra · Mathematics 2017-05-19 Juma Kasozi , David Ssevviiri , Vincent Umutabazi

A quasi-hereditary algebra is an algebra equipped with a certain partial order $\unlhd$ on its simple modules. Such a partial order -- called a quasi-hereditary structure -- gives rise to a characteristic tilting module $T_{\unlhd}$ by a…

Representation Theory · Mathematics 2025-07-23 Takahide Adachi , Aaron Chan , Yuta Kimura , Mayu Tsukamoto

We show that various derived categories of torsion modules and contramodules over the adic completion of a commutative ring by a weakly proregular ideal are full subcategories of the related derived categories of modules. By the work of…

Category Theory · Mathematics 2016-07-04 Leonid Positselski

We study Gorenstein categories. We show that such a category has Tate cohomological functors and Avramov-Martsinkovsky exact sequences connecting the Gorenstein relative, the absolute and the Tate cohomological functors. We show that such a…

Category Theory · Mathematics 2007-11-09 Edgar Enochs , Sergio Estrada , J. R. Garcia-Rozas

Let K be a comonad on a model category M. We provide conditions under which the associated category of K-coalgebras admits a model category structure such that the forgetful functor to M creates both cofibrations and weak equivalences. We…

Algebraic Topology · Mathematics 2014-02-26 Kathryn Hess , Brooke Shipley

Let $A$ be the path algebra of a quiver of Dynkin type $\mathbb{A}_n$. The module category $\text{mod}\,A$ has a combinatorial model as the category of diagonals in a polygon $S$ with $n+1$ vertices. The recently introduced notion of almost…

Representation Theory · Mathematics 2024-10-08 Thomas Brüstle , Eric J. Hanson , Sunny Roy , Ralf Schiffler

We extend the usual definition of coherence, for modules over rings, to partially ordered right modules over a large class of partially ordered rings, called po-rings. In this situation, coherence is equivalent to saying that solution…

General Mathematics · Mathematics 2007-05-23 Friedrich Wehrung

We characterise the (closeness classes of) quasi-isometric embeddings as the regular monomorphisms in the coarsely Lipschitz category, formalising the notion that they are isomorphisms onto their image. Furthermore, we prove that the…

Metric Geometry · Mathematics 2024-11-14 Robert Tang