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This paper is an MGM version of arXiv.org:1703.04266 and arXiv:1907.03364, and a follow-up to Section 5 of arXiv:1503.05523. In the setting of a commutative ring $S$ with a weakly proregular finitely generated ideal $J\subset S$, we…

Commutative Algebra · Mathematics 2025-12-08 Leonid Positselski

Let $R$ be a commutative Noetherian Henselian local ring. Denote by $\mathrm{mod} R$ the category of finitely generated $R$-modules, and by ${\mathcal G}$ the full subcategory of $\mathrm{mod} R$ consisting of all G-projective $R$-modules.…

Commutative Algebra · Mathematics 2007-05-23 Ryo Takahashi

We study classes of modules closed under direct sums, $\mathcal{M}$-submodules and $\mathcal{M}$-epimorphic images where $\mathcal{M}$ is either the class of embeddings, $RD$-embeddings or pure embeddings. We show that the…

Rings and Algebras · Mathematics 2024-08-19 Marcos Mazari-Armida , Jiri Rosicky

Let $\mathbb{k}$ be a commutative ring with global dimension zero. We show that we can rigidify homotopy coherent comodules in connective modules over the Eilenberg-Mac Lane spectrum of $\mathbb{k}$. That is, the $\infty$-category of…

Algebraic Topology · Mathematics 2024-04-09 Maximilien Péroux

We introduce the notions of Koszul $N$-complex, $\check{\mathrm{C}}$ech $N$-complex and telescope $N$-complex, explicit derived torsion and derived completion functors in the derived category $\mathbf{D}_N(R)$ of $N$-complexes using the…

Commutative Algebra · Mathematics 2020-06-24 Xiaoyan Yang

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

Let k be an algebraically closed field of characteristic 0, and let $A = k[x,y]/(f)$ be a quasi-homogeneous plane curve. We show that for any graded torsion free A-module M, there exists a natural graded integrable connection, i.e. a graded…

Algebraic Geometry · Mathematics 2008-08-26 Eivind Eriksen

In this note we introduce and study basic properties of two types of modules over a commutative noetherian ring $R$ of positive prime characteristic. The first is the category of modules of finite $F$-type. These objects include reflexive…

Commutative Algebra · Mathematics 2016-03-02 Hailong Dao , Tony Se

In abelian categories like the category of R-modules and even in the category S-Act 0 of S-acts with a unique zero, idempotent radicals and torsion theories are equivalent, and the {\tau}-torsion and {\tau}- torsion free classes of a…

Representation Theory · Mathematics 2018-06-20 M. Haddadi , S. M. N. Sheykholislami

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

Let R be a ring (not necessarily commutative). A left R-module is said to be cotorsion if Ext 1 R (G, M) = 0 for any flat R-module G. It is well known that each pure-injective left R-module is cotorsion, but the converse does not hold: for…

Rings and Algebras · Mathematics 2016-03-25 Francois Couchot

For a finite-dimensional gentle algebra, it is already known that the functorially finite torsion classes of its category of finite-dimensional modules can be classified using a combinatorial interpretation, called maximal non-crossing sets…

Representation Theory · Mathematics 2020-09-23 Aaron Chan , Laurent Demonet

For a category $\mathcal E$ with finite limits and well-behaved countable coproducts, we construct a model structure, called the effective model structure, on the category of simplicial objects in $\mathcal E$, generalising the Kan--Quillen…

Category Theory · Mathematics 2022-11-11 Nicola Gambino , Simon Henry , Christian Sattler , Karol Szumiło

In this paper, we study ICE-closed (= Image-Cokernel-Extension-closed) subcategories of an abelian length category using torsion classes. To each interval $[\mathcal{U},\mathcal{T}]$ in the lattice of torsion classes, we associate a…

Representation Theory · Mathematics 2022-08-08 Haruhisa Enomoto , Arashi Sakai

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 the category whose objects are graphs of fixed genus and whose morphisms are contractions. We show that the corresponding contravariant module categories are Noetherian and we study two families of modules over these categories.…

Combinatorics · Mathematics 2020-07-20 Nicholas Proudfoot , Eric Ramos

Let R be a commutative noetherian ring. The notion of n-wide subcategories of Mod R is introduced and studied in Matsui-Nam-Takahashi-Tri-Yen in relation to the cohomological dimension of a specialization-closed subset of Spec R. In this…

Commutative Algebra · Mathematics 2020-09-28 Hiroki Matsui , Ryo Takahashi

We develop a theory of curved A-infinity-categories around equivalences of their module categories. This allows for a uniform treatment of curved and uncurved A-infinity-categories which generalizes the classical theory of uncurved…

Algebraic Geometry · Mathematics 2015-10-16 Jeffrey Armstrong , Patrick Clarke

By the Telescope Conjecture for Module Categories, we mean the following claim: "Let R be any ring and (A, B) be a hereditary cotorsion pair in Mod-R with A and B closed under direct limits. Then (A, B) is of finite type." We prove a…

Rings and Algebras · Mathematics 2008-09-16 Jan Saroch , Jan Stovicek

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
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