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Related papers: The braided Ptolemy-Thompson group $T^*$ is asynch…

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We define pseudo-Garside groups and prove a theorem about them parallel to Garside's result on the word problem for the usual braid groups. The main novelty is that the set of simple elements can be infinite. We introduce a group B=B(Z^n)…

Group Theory · Mathematics 2007-05-23 Daan Krammer

The second author showed how Katsura's construction of the C*-algebra of a topological graph E may be twisted by a Hermitian line bundle L over the edge space E. The correspondence defining the algebra is obtained as the completion of the…

Operator Algebras · Mathematics 2017-01-25 Alex Kumjian , Hui Li

In the present paper, we show that many combinatorial and topological objects, such as maps, hypermaps, three-dimensional pavings, constellations and branched coverings of the two--sphere admit any given finite automorphism group. This…

Combinatorics · Mathematics 2020-01-16 Rémi Bottinelli , Laura Grave de Peralta , Alexander Kolpakov

In this article, we introduce a new family of groups, called Chambord groups and constructed from braided strand diagrams associated to specific semigroup presentations. It includes the asymptotically rigid mapping class groups previously…

Group Theory · Mathematics 2024-06-21 Anthony Genevois , Anne Lonjou , Christian Urech

In this note, we show that the sets of all stable commutator lengths in the braided Ptolemy-Thompson groups are equal to non-negative rational numbers.

Group Theory · Mathematics 2020-03-02 Shuhei Maruyama

We show that many normal subgroups of the braid group modulo its centre, and of the mapping class group of a sphere with marked points, have the property that their automorphism and abstract commensurator groups are mapping class groups of…

Geometric Topology · Mathematics 2018-05-10 Alan McLeay

The main result of this article is that any braided (resp. annular, planar) diagram group $D$ splits as a short exact sequence $1 \to R \to D \to S \to 1$ where $R$ is a subgroup of some right-angled Artin group and $S$ a subgroup of…

Group Theory · Mathematics 2019-08-26 Anthony Genevois

We introduce the notion of measurable bounded cohomology for measured groupoids, extending continuous bounded cohomology of locally compact groups. We show that the measurable bounded cohomology of the semidirect groupoid associated to a…

Dynamical Systems · Mathematics 2025-09-19 Filippo Sarti , Alessio Savini

This note serves as a short and reader-friendly introduction to twisted Brin-Thompson groups, which were recently constructed by Belk and the author to provide a family of simple groups with a variety of interesting properties. Most…

Group Theory · Mathematics 2022-01-04 Matthew C. B. Zaremsky

In this paper, we introduce a symmetric continuous cohomology of topological groups. This is obtained by topologizing a recent construction due to Staic (J. Algebra 322 (2009), 1360-1378), where a symmetric cohomology of abstract groups is…

Group Theory · Mathematics 2013-06-04 Mahender Singh

We show that the automorphism groups of countably categorical linear orders are extremely amenable. Using methods of Kechris, Pestov, and Todorcevic, we use this fact to derive a structural Ramsey theorem for certain families of finite…

Logic · Mathematics 2014-02-17 François G. Dorais , Steven Gubkin , Daniel McDonald , Manuel Rivera

We show that Thompson's group F is the symmetry group of the "generic idempotent". That is, take the monoidal category freely generated by an object A and an isomorphism A \otimes A --> A; then F is the group of automorphisms of A.

Group Theory · Mathematics 2010-03-15 Marcelo Fiore , Tom Leinster

In a recent paper Uffe Haagerup and Kristian Knudsen Olesen show that for Richard Thompson's group $T$, if there exists a finite set $H$ which can be decomposed as disjoint union of sets $H_1$ and $H_2$ with $\sum_{g\in…

Operator Algebras · Mathematics 2014-10-07 Collin Bleak , Kate Juschenko

The braid groups B_n can be defined as the mapping class group of the n-punctured disc. The Lawrence-Krammer representation of the braid group B_n is the induced action on a certain twisted second homology of the space of unordered pairs of…

Group Theory · Mathematics 2007-05-23 Stephen J. Bigelow

Given a measurable twisted action of a second-countable, locally compact group G on a separable C*-algebra A, we prove the existence of a topology on AxG making it a continuous bundle, whose cross sectional C*-algebra is isomorphic to the…

funct-an · Mathematics 2008-02-03 Ruy Exel , Marcelo Laca

We construct a braided version of Thompson's group V.

Group Theory · Mathematics 2013-09-04 Matthew G. Brin

We study the action of the mapping class group on the real homology of finite covers of a topological surface. We use the homological representation of the mapping class to construct a faithful infinite-dimensional representation of the…

Geometric Topology · Mathematics 2010-06-18 Thomas Koberda

A left orderable completely metrizable topological group is exhibited containing Artin's braid group on infinitely many strands. The group is the mapping class group (rel boundary) of the closed unit disk with a sequence of interior…

Geometric Topology · Mathematics 2007-05-23 Paul Fabel

This paper demonstrates the uniformly finite homology developed by Block and Weinberger and its relationship to amenable spaces via applications to the Cayley graph of Thompson's Group F. In particular, a certain class of subgraph of F is…

Group Theory · Mathematics 2009-03-11 Dan Staley

The paper is devoted to prove a version of Milnor-Moore Theorem for connected braided bialgebras that are infinitesimally cocommutative. Namely in characteristic different from 2, we prove that, for a given connected braided bialgebra $A$…

Quantum Algebra · Mathematics 2008-04-18 A. Ardizzoni , C. Menini , D. Stefan