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Coherence is here demonstrated for sesquicartesian categories, which are categories with nonempty finite products and arbitrary finite sums, including the empty sum, where moreover the first and the second projection from the product of the…

Category Theory · Mathematics 2007-05-23 K. Dosen , Z. Petric

Let $G$ denote a possibly discrete topological group admitting an open subgroup $I$ which is pro-$p$. If $H$ denotes the corresponding Hecke algebra over a field $k$ of characteristic $p$ then we study the adjunction between $H$-modules and…

Representation Theory · Mathematics 2023-03-06 Nicolas Dupré , Jan Kohlhaase

We introduce a new method for expanding an abelian category and study it using recollements. In particular, we give a criterion for the existence of cotilting objects. We show, using techniques from noncommutative algebraic geometry, that…

Representation Theory · Mathematics 2015-05-11 Boris Lerner , Steffen Oppermann

We investigate the behavior of singularity categories and stable categories of Gorenstein projective modules along a morphism of rings. The natural context to approach the problem is via change of rings, that is, the classical adjoint…

Representation Theory · Mathematics 2018-11-19 Steffen Oppermann , Chrysostomos Psaroudakis , Torkil Stai

We characterize projective objects in the category of internal crossed modules within any semi-abelian category. When this category forms a variety of algebras, the internal crossed modules again constitute a semi-abelian variety, ensuring…

Category Theory · Mathematics 2026-01-09 Maxime Culot

Projectively coresolved Gorenstein flat modules were introduced recently by Saroch and Stovicek and were shown to be Gorenstein projective. While the relation between Gorenstein projective and Gorenstein flat modules is not well understood,…

Rings and Algebras · Mathematics 2023-11-07 Ilias Kaperonis , Dimitra-Dionysia Stergiopoulou

For an adjoint pair $(F, G)$ of functors, we prove that $G$ is a separable functor if and only if the defined monad is separable and the associated comparison functor is an equivalence up to retracts. In this case, under an idempotent…

Rings and Algebras · Mathematics 2016-11-01 Xiao-Wu Chen

For a left coherent ring A with every left ideal having a countable set of generators, we show that the coderived category of left A-modules is compactly generated by the bounded derived category of finitely presented left A-modules…

Category Theory · Mathematics 2017-03-21 Leonid Positselski

A model structure on a category is a formal way of introducing a homotopy theory on that category, and if the model structure is abelian and hereditary, its homotopy category is known to be triangulated. So a good way to both build and…

Rings and Algebras · Mathematics 2024-01-25 Driss Bennis , Rachid El Maaouy , Juan Ramón García Rozas , Luis Oyonarte

Let $\mathsf{Ord} $ be the category of (pre)ordered sets. Unlike $\mathsf{Ord}/X$, whose behaviour is well-known, not much can be found in the literature about the lax comma 2-category $\mathsf{Ord} //X$. In this paper we show that the…

Category Theory · Mathematics 2023-11-13 Maria Manuel Clementino , Fernando Lucatelli Nunes

We develop the theory of recollements in a stable $\infty$-categorical setting. In the axiomatization of Beilinson, Bernstein and Deligne, recollement situations provide a generalization of Grothendieck's "six functors" between derived…

Category Theory · Mathematics 2016-05-27 Domenico Fiorenza , Fosco Loregian

Let $R$ be a noetherian algebra over a Cohen--Macaulay ring admitting a canonical module, and assume that $R$ is maximal Cohen--Macaulay over the base ring. We provide a characterization of when $R$ is left weakly Gorenstein. We further…

Rings and Algebras · Mathematics 2026-03-03 Souvik Dey , Jian Liu , Xue-Song Lu

In this short \'etude, we observe that the full structure of a recollement on a stable infinity-category can be reconstructed from minimal data: that of a reflective and coreflective full subcategory. The situation has more symmetry than…

Category Theory · Mathematics 2016-07-08 Clark Barwick , Saul Glasman

A ring $R$ is called left GF-closed, if the class of all Gorenstein flat left $R$-modules is closed under extensions. The class of left GF-closed rings includes strictly the one of right coherent rings and the one of rings of finite weak…

Commutative Algebra · Mathematics 2008-01-09 D. Bennis

In this paper we give bountiful examples of Gorenstein local rings $A$ and $B$ such that there is a triangle equivalence between the stable categories \underline{CM}($A$), \underline{CM}($B$).

Commutative Algebra · Mathematics 2025-02-19 Tony J. Puthenpurakal

The main goal of this paper is to prove the following: for a triangulated category $ \underline{C}$ and $E\subset \operatorname{Obj} \underline{C}$ there exists a cohomological functor $F$ (with values in some abelian category) such that…

K-Theory and Homology · Mathematics 2016-02-01 Mikhail V. Bondarko , Vladimir A. Sosnilo

Gorenstein homological dimensions are refinements of the classical homological dimensions, and finiteness singles out modules with amenable properties reflecting those of modules over Gorenstein rings. As opposed to their classical…

Commutative Algebra · Mathematics 2007-05-23 L. Winther Christensen , A. Frankild , H. Holm

In this paper we show that the (un)bounded derived categories$\colon$(i) of the monomorphism category, (ii) of the morphism category and (iii) of the double morphism category, admit a periodic infinite ladder of recollements. These results…

Representation Theory · Mathematics 2016-06-24 Nan Gao , Chrysostomos Psaroudakis

To a big n-tilting object in a complete, cocomplete abelian category A with an injective cogenerator we assign a big n-cotilting object in a complete, cocomplete abelian category B with a projective generator, and vice versa. Then we…

Category Theory · Mathematics 2021-01-13 Leonid Positselski , Jan Stovicek

Let $(\mathcal{C},\mathbb{E},\mathfrak{s})$ be an extriangulated category with a proper class $\xi$ of $\mathbb{E}$-triangles. In this paper, we study the quasi-Gorensteinness of extriangulated categories. More precisely, we introduce the…

Representation Theory · Mathematics 2025-01-14 Zhenggang He