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Let $H$ be a Hopf algebra in braided category $\cal C$. Crossed modules over $H$ are objects with both module and comodule structures satisfying some comatibility condition. Category ${\cal C}^H_H$ of crossed modules is braided and is…

High Energy Physics - Theory · Physics 2008-02-03 Yuri Bespalov

We study the category of $\mathbf{P}$-equivariant modules over the infinite variable polynomial ring, where $\mathbf{P}$ denotes the subgroup of the infinite general linear group $\mathbf{GL}(\mathbf{C}^\infty)$ consisting of elements…

Commutative Algebra · Mathematics 2024-07-04 Teresa Yu

We extend our previous results on generalized Dixmier-Douady theory to graded $C^*$-algebras, as means for explicit computations of the invariants arising for bundles of ungraded $C^*$-algebras. For a strongly self-absorbing $C^*$-algebra…

Operator Algebras · Mathematics 2026-01-08 Marius Dadarlat , Ulrich Pennig

In this paper, we study modules over quotient spaces of certain categorified fiber bundles. These are understood as modules over entwining structures involving a small $K$-linear category $\mathcal D$ and a $K$-coalgebra $C$. We obtain…

Category Theory · Mathematics 2019-06-04 Mamta Balodi , Abhishek Banerjee , Samarpita Ray

We study the classification of submodules of module categories over monoidal categories, extending ideas of Coulembier on the classification of tensor ideals in monoidal categories. We develop a framework that applies to module categories…

Representation Theory · Mathematics 2026-03-20 Hadi Salmasian , Alistair Savage , Yaolong Shen

A finite tensor category is called pointed if all its simple objects are invertible. We find necessary and sufficient conditions for two pointed semisimple categories to be dual to each other with respect to a module category. Whenever the…

Quantum Algebra · Mathematics 2009-12-19 Deepak Naidu

For any cssc-crossed module a category is constructed, equipped with a structure and proved that this is a coherent categorical group. Together with a result of the previous paper, where to any categorical group the cssc-crossed module is…

Category Theory · Mathematics 2024-10-15 Tamar Datuashvili , Osman Mucuk , Nazmiye Alemdar , Tunçar Şahan

Let A be a commutative ring with 1/2 in A. In this paper, we define new characteristic classes for finitely generated projective A-modules V provided with a non degenerate quadratic form. These classes belong to the usual K-theory of A.…

K-Theory and Homology · Mathematics 2010-12-20 Max Karoubi

We classify indecomposable commutative separable (special Frobenius) algebras and their local modules in (untwisted) group-theoretical modular categories. This gives a description of modular invariants for group-theoretical modular data. As…

Quantum Algebra · Mathematics 2009-08-10 Alexei Davydov

We establish an algebra-isomorphism between the complexified Grothendieck ring F of certain bimodule categories over a modular tensor category and the endomorphism algebra of appropriate morphism spaces of those bimodule categories. This…

Category Theory · Mathematics 2009-02-24 Jurgen Fuchs , Ingo Runkel , Christoph Schweigert

In [8] we proved that any categorical group defines a c-crossed module, which is a cssc-crossed module defined in the same paper. In [9] we constructed a categorical group for any cssc-crossed module. In the presented paper we prove that…

Category Theory · Mathematics 2025-09-03 Tamar Datuashvili , Osman Mucuk , Nazmiye Alemdar , Tunçar Şahan

Given a pivotal module category over a spherical fusion category, we introduce the encircling module, a module over the fusion algebra defined using the pivotal structure, and prove that it is isomorphic to the NIM-rep as a fusion algebra…

Quantum Algebra · Mathematics 2026-03-25 Alastair King , Leonard Hardiman

We develop the theory of Hopf bimodules for a finite rigid tensor category C. Then we use this theory to define a distinguished invertible object D of C and an isomorphism of tensor functors ?^{**} and D tensor ^{**}? tensor D^{-1}. This…

Quantum Algebra · Mathematics 2009-05-19 Pavel Etingof , Dmitri Nikshych , Viktor Ostrik

Let G be a unipotent algebraic group over an algebraically closed field k of characteristic p > 0 and let l be a prime different from p. Let e be a minimal idempotent in D_G(G), the braided monoidal category of G-equivariant (under…

Representation Theory · Mathematics 2013-12-17 Tanmay Deshpande

We apply the yoga of classical homotopy theory to classification problems of G-extensions of fusion and braided fusion categories, where G is a finite group. Namely, we reduce such problems to classification (up to homotopy) of maps from BG…

Quantum Algebra · Mathematics 2009-12-29 Pavel Etingof , Dmitri Nikshych , Victor Ostrik , with an appendix by Ehud Meir

We introduce the notion of the $\infty$-category of (complete) derived $G$-graded modules over a $G$-graded ring $R$ for a torsion-free abelian group $G$, and we study its foundational properties. Moreover, we prove a categorical…

Commutative Algebra · Mathematics 2026-04-06 Ryo Ishizuka , Shou Yoshikawa

We introduce and study the new notion of an {\em exact factorization} $\mathcal{B}=\mathcal{A}\bullet \mathcal{C}$ of a fusion category $\mathcal{B}$ into a product of two fusion subcategories $\mathcal{A},\mathcal{C}\subseteq \mathcal{B}$…

Quantum Algebra · Mathematics 2017-03-16 Shlomo Gelaki

Category theoretic aspects of non-rational conformal field theories are discussed. We consider the case that the category C of chiral sectors is a finite tensor category, i.e. a rigid monoidal category whose class of objects has certain…

High Energy Physics - Theory · Physics 2007-05-23 Jurgen Fuchs

Let $K$ be a field, $\Gamma $ a finite group of field automorphisms of $K$, $F$ the $\Gamma $-fixed field in $K$ and $G\leq $GL$_v(K)$ a finite matrix group. Then the action of $\Gamma $ defines a grading on the symmetric algebra of the…

Number Theory · Mathematics 2023-11-21 Gabriele Nebe , Leonie Scheeren

We define a general notion of centrally $\Gamma$-graded sets and groups and of their graded products, and prove some basic results about the corresponding categories: most importantly, they form braided monoidal categories. Here, $\Gamma$…

Category Theory · Mathematics 2021-09-03 Wolfgang Bertram