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We describe Artin's braid group on a (fixed) finite number of strings as a crossed module over itself. In particular, we interpret the braid relations as crossed module structure relations.

Algebraic Topology · Mathematics 2013-03-12 Johannes Huebschmann

We study braided Hochschild and cyclic homology of ribbon algebras in braided monoidal categories, as introduced by Baez and by Akrami and Majid. We compute this invariant for several examples coming from quantum groups and braided groups.

Quantum Algebra · Mathematics 2010-08-13 Tom Hadfield , Ulrich Kraehmer

In this work, we introduce the notion of a partial action of a group on a strict monoidal category. We propose, in the context of Monoidal categories, new constructions analogous to those existing for partial group actions over an algebra…

Category Theory · Mathematics 2024-12-18 Eliezer Batista , Felipe Lopes Castro , Mykola Khrypchenko

Homotopy limits and colimits are homotopical replacements for the usual limits and colimits of category theory, which can be approached either using classical explicit constructions or the modern abstract machinery of derived functors. Our…

Algebraic Topology · Mathematics 2009-07-01 Michael Shulman

We present here definitions and constructions basic for the theory of monoidal and tensor categories. We provide references to the original sources, whenever possible. Group-theoretical categories are used as examples

Category Theory · Mathematics 2023-11-13 Alexei Davydov

The Hochschild homology and cohomology group can be described in terms of the homology and cohomology of the classifying space of the groupoid of the adjoint action of the group under the suitable assumption of the finiteness of the…

Representation Theory · Mathematics 2019-01-30 A. S. Mishchenko

While computer programs and logical theories begin by declaring the concepts of interest, be it as data types or as predicates, network computation does not allow such global declarations, and requires *concept mining* and *concept…

Category Theory · Mathematics 2023-11-03 Toshiki Kataoka , Dusko Pavlovic

Various simplicial complexes can be associated with a graph. Box complexes form an important families of such simplicial complexes and are especially useful for providing lower bounds on the chromatic number of the graph via some of their…

Combinatorics · Mathematics 2024-01-05 Hamid Reza Daneshpajouh , Frédéric Meunier

We adapt the notion of an algebraic theory to work in the setting of quasicategories developed recently by Joyal and Lurie. We develop the general theory at some length. We study one extended example in detail: the theory of commutative…

Algebraic Topology · Mathematics 2011-09-09 James Cranch

Pursuing a generalization of group symmetries of modular categories to category symmetries in topological phases of matter, we study linear Hopf monads. The main goal is a generalization of extension and gauging group symmetries to category…

Quantum Algebra · Mathematics 2019-11-05 Shawn X. Cui , Modjtaba Shokrian Zini , Zhenghan Wang

The primary goal of this paper is to abstract notions, results and constructions from the theory of categories to the broader setting of plots. Loosely speaking, a plot can be thought of as a non-associative non-unital category with a…

Category Theory · Mathematics 2016-04-06 Salvatore Tringali

Various descending chains of subgroups of a finite permutation group can be used to define a sequence of `basic' permutation groups that are analogues of composition factors for abstract finite groups. Primitive groups have been the…

Group Theory · Mathematics 2007-05-23 Cheryl E. Praeger

Equivariant monoids are very important objects in many branches of mathematics: they combine the notion of multiplication and the concept of a group action. In this paper we will construct categories which encode the structure borne by…

Category Theory · Mathematics 2024-11-19 Daniel Graves

We show that the author's notion of Galois extensions of braided tensor categories [22], see also [3], gives rise to braided crossed G-categories, recently introduced for the purposes of 3-manifold topology [31]. The Galois extensions C…

Category Theory · Mathematics 2007-05-23 Michael Mueger

A sufficient condition for the uniqueness of multinomial sequential unbiased estimators is provided generalizing a classical result for binomial samples. Unbiased estimators are applied to infer the parameters of multidimensional or…

Statistics Theory · Mathematics 2014-03-06 Enrico Bibbona , Alessandro Rubba

We generalize the result of Brandenbursky and Marcinkowski for the bounded cohomology of transformation groups to infinite volume case. To state the result, we introduce the notion of norm controlled cohomology as a generalization of…

Geometric Topology · Mathematics 2023-02-16 Mitsuaki Kimura

In this paper, we generalizing the main result in Liu[10] to weak Hopf coquasigroups case. We first define and study group-cograded weak Hopf quasigroups, which generalize both group-cograded Hopf quasigroups and weak Hopf group-coalgebras.…

Rings and Algebras · Mathematics 2022-12-02 Huili Liu , Lingli Zhu , Tao Yang

Twisted \'etale groupoid algebras have been studied recently in the algebraic setting by several authors in connection with an abstract theory of Cartan pairs of rings. In this paper, we show that extensions of ample groupoids correspond in…

Rings and Algebras · Mathematics 2021-01-26 Benjamin Steinberg

A natural problem in combinatorial rigidity theory concerns the determination of the rigidity or flexibility of bar-joint frameworks in $\mathbb{R}^d$ that admit some non-trivial symmetry. When $d=2$ there is a large literature on this…

Combinatorics · Mathematics 2025-09-30 Sean Dewar , Georg Grasegger , Eleftherios Kastis , Anthony Nixon

The action of any group on itself by conjugation and the corresponding conjugacy relation play an important role in group theory. There have been many attempts to find notions of conjugacy in semigroups that would be useful in special…

Group Theory · Mathematics 2021-01-19 J. Araújo , Michael Kinyon , Janusz Konieczny , António Malheiro