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We complete the computation of the integral homology of the generalized braid group $B$ associated to an arbitrary irreducible complex reflection group $W$ of exceptional type. In order to do this we explicitely computed the…

Group Theory · Mathematics 2016-05-24 Ivan Marin

We define a category of divided Dieudonn\'e crystals which classifies p-divisible groups over schemes in characteristic p with certain finiteness conditions, including all F-finite noetherian schemes. For formally smooth schemes or locally…

Algebraic Geometry · Mathematics 2018-11-26 Eike Lau

Given a set $A$ and an abelian group $B$ with operators in $A$, in the sense of Krull and Noether, we introduce the Ore group extension $B[x; \sigma_B, \delta_B]$ as the additive group $B[x]$, with $A[x]$ as a set of operators. Here, the…

Rings and Algebras · Mathematics 2025-08-28 Per Bäck , Patrik Lundström , Johan Öinert , Johan Richter

A key invariant of a braided categorical group is its quadratic form, introduced by Joyal and Street. We show that the categorical group is braided equivalent to a simultaneously skeletal and strictly associative one if and only if the…

Category Theory · Mathematics 2019-11-04 Oliver Braunling

This is a report on our long term project to find an algorithm to decide if a finitely presented group has a non-trivial action on a tree.

Geometric Topology · Mathematics 2022-03-07 A. N. Bartholomew , M. J. Dunwoody

The actions of 0-Kashiwara operators on the $U'_q(G_2^{(1)})$-crystal $B_l$ in [Yamane S., J. Algebra 210 (1998), 440-486] are made explicit by using a similarity technique from that of a $U'_q(D_4^{(3)})$-crystal. It is shown that…

Quantum Algebra · Mathematics 2010-03-10 Kailash C. Misra , Mahathir Mohamad , Masato Okado

In this paper we deal with the action of the symmetric group on the cohomology of the configuration space $C_n(d)$ of $n$ points in $\mathbb{R}^d$. This topic has been studied by several authors (see the introduction). On the cohomology…

Representation Theory · Mathematics 2009-09-29 Giacomo d'Antonio , Giovanni Gaiffi

We analyze finite orbits of the natural braid group action on the character variety of the $n$ times punctured sphere. Building on recent results relating middle convolution and finite complex reflection groups, our work implements Katz's…

Algebraic Geometry · Mathematics 2025-12-23 Amal Vayalinkal

We classify braided generalized near-group fusion categories whose global dimension is not an integer; there are exactly two up to Grothendieck equivalence and taking products with braided pointed fusion categories.

Quantum Algebra · Mathematics 2022-12-29 Andrew Schopieray

We compare two crossed homomorphisms on a braid group, one defined diagrammatically and the other defined algebraically. We show that these crossed homomorphisms are essentially the same, and compute them in detail for simple braids, namely…

Geometric Topology · Mathematics 2025-11-26 Yusuke Kuno , Yoshiro Yaguchi

If $X$ is a connected complex manifold with $d_X = 2$ that admits the holomorphic and transitive action of a (connected) Lie group $G$, then the action extends to an action of the complexification $\hat{G}$ of $G$ on $X$ except when either…

Complex Variables · Mathematics 2014-06-11 S. Ruhallah Ahmadi , Bruce Gilligan

Aiming for a revival of the theory of crystallographic complex reflection groups, we compute (minimal) Coxeter-like reflection presentations for the infinite families of those non-genuine groups which satisfy Steinberg's fixed point…

Group Theory · Mathematics 2025-10-10 Davide Dal Martello

We introduce a family of automorphisms on the bosonic extension of arbitrary type and show that they satisfy the braid relations. They preserve the global basis and the crystal basis. Using this braid group action, we define a subalgebra…

Representation Theory · Mathematics 2024-08-15 Masaki Kashiwara , Myungho Kim , Se-jin Oh , Euiyong Park

In a couple of previous papers, we initiated a systematic study of semihypergroups and had a thorough discussion on certain analytic and algebraic aspects associated to this class of objects. In this article, we introduce and examine…

Functional Analysis · Mathematics 2022-04-11 Choiti Bandyopadhyay

Our aim of this and subsequent papers is to enlighten (a part of, presumably) arithmetic structures of knots. This paper introduces a notion of profinite knots which extends topological knots and shows its various basic properties.…

Number Theory · Mathematics 2015-07-03 Hidekazu Furusho

Let $\Gamma$ be a finite group acting on a Lie group $G$. We consider a class of group extensions $1 \to G \to \hat{G} \to \Gamma \to 1$ defined by this action and a $2$-cocycle of $\Gamma$ with values in the centre of $G$. We establish and…

Differential Geometry · Mathematics 2024-06-14 G. Barajas , O. García-Prada , P. B. Gothen , I. Mundet i Riera

There is a natural action of the braid group on the symmetric matrices with units on the diagonal, appearing in various fields as Singularity Theory, Frobenius Manifolds or Isomonodromic deformations of certain classes of linear…

Mathematical Physics · Physics 2007-05-23 Alexandre Stefanov

For a braided fusion category $\mathcal{V}$, a $\mathcal{V}$-fusion category is a fusion category $\mathcal{C}$ equipped with a braided monoidal functor $\mathcal{F}:\mathcal{V} \to Z(\mathcal{C})$. Given a fixed $\mathcal{V}$-fusion…

Quantum Algebra · Mathematics 2021-04-28 Corey Jones , Scott Morrison , David Penneys , Julia Plavnik

We introduce and study the notion of continuous orbit equivalence of actions of countable discrete groups on Cartan pairs in (twisted) groupoid context. We characterize orbit equivalence of actions in terms of the corresponding…

Operator Algebras · Mathematics 2023-12-05 Massoud Amini , Mahdi Moosazadeh

Let $C$ be a simply laced generalized Cartan matrix. Given an element $b$ of the generalized braid semigroup related to $C$, we construct a collection of mutation-equivalent quivers with potentials. A quiver with potential in such a…

Representation Theory · Mathematics 2017-01-04 Efim Abrikosov