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Rigid meromorphic cocycles are defined in the setting of orthogonal groups of arbitrary real signature and constructed in some instances via a $p$-adic analogue of Borcherds' singular theta lift. The values of rigid meromorphic cocycles at…

Number Theory · Mathematics 2023-08-29 Henri Darmon , Lennart Gehrmann , Michael Lipnowski

In this paper, we investigate a non-commutative version of strongly flat modules, which is based on the concept of universal localization introduced by Cohn. We consider a set $\sigma$ consisting of maps of finitely generated projective…

Representation Theory · Mathematics 2025-08-11 Javad Asadollahi , Rasool Hafezi , Somayeh Sadeghi

An example is constructed of a local ring and a module of finite type and finite projective dimension over that ring such that the module is not rigid. This shows that the rigidity conjecture is false.

Commutative Algebra · Mathematics 2008-02-03 Raymond C. Heitmann

We present a bicategorical perspective on derived Morita theory for rings, DG algebras, and spectra. This perspective draws a connection between Morita theory and the bicategorical Yoneda Lemma, yielding a conceptual unification of Morita…

Algebraic Topology · Mathematics 2008-06-03 Niles Johnson

Let $G$ be a group and $\Bbbk$ a commutative ring. All categories and functors are assumed to be $\Bbbk$-linear. We define a $G$-invariant bimodule ${}_SM_R$ over $G$-categories $R, S$ and a $G$-graded bimodule ${}_BN_A$ over $G$-graded…

Representation Theory · Mathematics 2026-04-06 Hideto Asashiba , Shengyong Pan

Localisation is an important technique in ring theory and yields the construction of various rings of quotients. Colocalisation in comodule categories has been investigated by some authors where the colocalised coalgebra turned out to be a…

Rings and Algebras · Mathematics 2007-05-23 Christian Lomp , Virginia Rodrigues

We develop Morita theory for finitary additive 2-representations of finitary 2-categories. As an application we describe Morita equivalence classes for 2-categories of projective functors associated to finite dimensional algebras and for…

Representation Theory · Mathematics 2017-05-10 Volodymyr Mazorchuk , Vanessa Miemietz

Let $(S, \n)$ be a commutative noetherian local ring and $\omega\in\n$ be non-zerodivisor. This paper deals with the behavior of the category $\mon(\omega, \cp)$ consisting of all monomorphisms between finitely generated projective…

Commutative Algebra · Mathematics 2023-07-26 Abdolnaser Bahlekeh , Fahimeh Sadat Fotouhi , Armin Nateghi , Shokrollah Salarian

All rings considered are commutative. In this article we introduce and study two notions of modules which are stronger than CS modules, namely weakly IN modules and strongly CS modules. Our main aim is to characterize when a trivial…

Rings and Algebras · Mathematics 2021-12-21 Farid Kourki , Rachid Tribak

A relationship between curved differential algebras and corings is established and explored. In particular it is shown that the category of semi-free curved differential graded algebras is equivalent to the category of corings with…

Rings and Algebras · Mathematics 2013-01-28 Tomasz Brzeziński

A semiring generalises the notion of a ring, replacing the additive abelian group structure with that of a commutative monoid. In this paper, we study a notion positioned between a ring and a semiring -- a semiring whose additive monoid is…

Rings and Algebras · Mathematics 2024-11-20 Peter F. Faul , Amartya Goswami , Gideo Joubert , Graham Manuell

Rigid monoidal 1-categories are ubiquitous throughout quantum algebra and low-dimensional topology. We study a generalization of this notion, namely rigid algebras in an arbitrary monoidal 2-category. Examples of rigid algebras include…

Quantum Algebra · Mathematics 2023-06-16 Thibault D. Décoppet

Graded rings provide a natural algebraic framework for encoding symmetry via decompositions into homogeneous components indexed by a group, together with multiplication rules reflecting the group operation. Among graded rings, strongly…

Rings and Algebras · Mathematics 2026-05-12 Joakim Arnlind , Stefan Wagner

2-Theories are a canonical way of describing categories with extra structure. 2-theory-morphisms are used when discussing how one structure can be replaced with another structure. This is central to categorical coherence theory. We place a…

Category Theory · Mathematics 2007-05-23 Noson S. Yanofsky

The monoidal version of classical Morita theory is a theory of bialgebroids. To make this explicit we construct a bicategory the objects of which are the bialgebroids and in which equivalence of objects means that the corresponding module…

Quantum Algebra · Mathematics 2007-05-23 K. Szlachanyi

A modular fusion category C allows one to define projective representations of the mapping class groups of closed surfaces of any genus. We show that if all these representations are irreducible, then C has a unique Morita-class of simple…

Quantum Algebra · Mathematics 2021-06-08 Iordanis Romaidis , Ingo Runkel

We provide concrete models for generalized morphisms and Morita equivalences of topological 2-groupoids by introducing the notions of crossings and crossed extensions of groupoid crossed modules. A systematic study of these objects is…

Algebraic Topology · Mathematics 2018-02-07 El-kaïoum M. Moutuou

We give an example of a Morita algebra $A$ with a tilting module $T$ such that the algebra $End_A(T)$ has dominant dimension at least two but is not a Morita algebra. This provides a counterexample to a conjecture by Chen and Xi from…

Representation Theory · Mathematics 2018-01-19 Bernhard Boehmler , Rene Marczinzik

Given a category $\mathcal C$ and a directed partially ordered set $J$, a certain category $pro^J -\mathcal C$ on inverse systems in $\mathcal C$ is constructed such that the ordinary pro-category $pro-\mathcal C$ is the most special case…

Category Theory · Mathematics 2019-05-20 Nikica Uglešić

We study the interplay between the notions of $n$-coherent rings and finitely $n$-presented modules, and also study the relative homological algebra associated to them. We show that the $n$-coherency of a ring is equivalent to the thickness…

Rings and Algebras · Mathematics 2017-09-05 Daniel Bravo , Marco A. Pérez