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We introduce forest diagrams and strand diagrams for elements of Thompson's group F. A forest diagram is a pair of infinite, bounded binary forests together with an order-preserving bijection of the leaves. Using forest diagrams, we derive…

Group Theory · Mathematics 2007-08-28 James Belk

A remarkable result of Thompson states that a finite group is soluble if and only if its two-generated subgroups are soluble. This result has been generalized in numerous ways, and it is in the core of a wide area of research in the theory…

Group Theory · Mathematics 2019-08-12 P. Hauck , L. S. Kazarin , A. Martínez-Pastor , M. D. Pérez-Ramos

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

We study the finiteness properties of the braided Higman--Thompson group $bV_{d,r}(H)$ with labels in $H\leq B_d$, and $bF_{d,r}(H)$ and $bT_{d,r}(H)$ with labels in $H\leq PB_d$ where $B_d$ is the braid group with $d$ strings and $PB_d$ is…

Group Theory · Mathematics 2023-08-17 Rachel Skipper , Xiaolei Wu

We prove that the braided Thompson's groups $V_{\rm br}$ and $F_{\rm br}$ are of type $F_\infty$, confirming a conjecture by John Meier. The proof involves showing that matching complexes of arcs on surfaces are highly connected. In an…

Group Theory · Mathematics 2021-06-23 Kai-Uwe Bux , Martin Fluch , Marco Marschler , Stefan Witzel , Matthew C. B. Zaremsky

A generalization of the topological fundamental group is developed in order to exhibit a topologically complete braid group containing Artin's braid group on infinitely many strands with respect to the following notion of convergence: A…

Geometric Topology · Mathematics 2007-05-23 Paul Fabel

The central extension of the Thompson group $T$ that arises in the quantized Teichm\"uller theory is 12 times the Euler class. This extension is obtained by taking a (partial) abelianization of the so-called braided Ptolemy-Thompson group…

Geometric Topology · Mathematics 2014-02-26 Louis Funar , Vlad Sergiescu

We describe a procedure for constructing a generalized Thompson group out of a family of groups that is equipped with what we call a cloning system. The previously known Thompson groups F, V, Vbr and Fbr arise from this procedure using,…

Group Theory · Mathematics 2018-10-25 Stefan Witzel , Matthew C. B. Zaremsky

We describe pure braided versions of Thompson's group F. These groups, $BF$ and $\hat{BF}$, are subgroups of the braided versions of Thompson's group V, introduced by Brin and Dehornoy. Unlike V, elements of F are order-preserving self-maps…

Group Theory · Mathematics 2018-03-19 Thomas Brady , Jose Burillo , Sean Cleary , Melanie Stein

We study a class of generalisations of Thompson's group $V$ arising naturally as topological full groups of purely infinite, minimal groupoids. In the process, we show that the derived subgroup of such a group is 2-generated whenever it is…

Group Theory · Mathematics 2024-04-29 Eusebio Gardella , Owen Tanner

The word problem for discrete groups is well-known to be undecidable by a Turing Machine; more precisely, it is reducible both to and from and thus equivalent to the discrete Halting Problem. The present work introduces and studies a real…

Logic in Computer Science · Computer Science 2007-05-23 Martin Ziegler , Klaus Meer

We demonstrate the existence of a family of finitely generated subgroups of Richard Thompson's group $F$ which is strictly well-ordered by the embeddability relation in type $\epsilon_0 +1$. All except the maximum element of this family…

Group Theory · Mathematics 2021-02-09 Collin Bleak , Matthew G. Brin , Justin Tatch Moore

We investigate a group $B\_\bullet$ that includes Artin's braid group $B\_\infty$ and Thompson's group $F$. The elements of $B\_\bullet$ are represented by braids diagrams in which the distances between the strands are not uniform and,…

Group Theory · Mathematics 2007-05-23 Patrick Dehornoy

This article is dedicated to the computation of an explicit presentation of some asymptotically rigid mapping class groups, namely the braided Higman-Thompson groups. To do so, we use the action of these groups on the spine complex, a…

Group Theory · Mathematics 2025-10-14 Anthony Genevois , Anne Lonjou , Christian Urech

We establish several results on the word problem for just infinite groups. First, for finitely generated just infinite groups we show that the word problem is uniformly decidable for presentations with recursively enumerable sets of…

Group Theory · Mathematics 2026-03-30 Alexey Talambutsa

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

We show that the monoids totM_{k,1} introduced by Birget and their generalizations tot nM_{k,r} which extend the Brin-Higman-Thompson groups, can be realized as the endomorphism monoids of higher-dimensional J\'onsson-Tarski algebras. We…

Rings and Algebras · Mathematics 2026-01-21 Bill de Witt , Luna Elliott

We define a family of groups that generalises Thompson's groups $T$ and $G$ and also those of Higman, Stein and Brin. For groups in this family we descrine centralisers of finite subgroups and show, that for a given finite subgroup $Q$,…

Group Theory · Mathematics 2013-09-10 Conchita Martinez-Perez , Brita E. A. Nucinkis

We show that an accessible group with infinitely many ends has property $R_{\infty}$. That is, it has infinitely many twisted conjugacy classes for any twisting automorphism. We deduce that having property $R_{\infty}$ is undecidable…

Group Theory · Mathematics 2026-03-02 Francesco Fournier-Facio , Harry Iveson , Armando Martino , Wagner Sgobbi , Peter Wong

William W. Boone and Graham Higman proved that a finitely generated group has soluble word problem if and only if it can be embedded in a simple group that can be embedded in a finitely presented group. We prove the exact analogue for…

Group Theory · Mathematics 2007-10-10 A. M. W. Glass