English
Related papers

Related papers: Thompson's group F is not almost convex

200 papers

We prove new results about the remarkable infinite simple groups introduced by Richard Thompson in the 1960s. We define the groups as partial transformation groups and we give a faithful representation in the Cuntz C*-algebra. For the…

Group Theory · Mathematics 2007-05-23 Jean-Camille Birget

This is a survey of our recent results on the amenability problem for Thompson's group $F$. They mostly concern esimating the density of finite subgraphs in Cayley graphs of $F$ for various systems of generators, and also equations in the…

Group Theory · Mathematics 2024-02-14 Victor Guba

We find new presentations for the Thompson's groups $F$, the derived group $F^{'}$ and the intermediate group $D$. These presentations have a common ground in that their relators are the same and only the generating sets differ. As an…

Group Theory · Mathematics 2008-12-02 Uffe Haagerup , Gabriel Picioroaga

Recall that a group $G$ is said to be $\frac{3}{2}$-generated if every non-trivial element $g\in G$ has a co-generator in $G$ (i.e., an element which together with $g$ generates $G$). Thompson's group $V$ was proved to be…

Group Theory · Mathematics 2024-03-01 Gili Golan

We consider random subgroups of Thompson's group $F$ with respect to two natural stratifications of the set of all $k$ generator subgroups. We find that the isomorphism classes of subgroups which occur with positive density are not the same…

Group Theory · Mathematics 2018-03-19 Sean Cleary , Murray Elder , Andrew Rechnitzer , Jennifer Taback

We introduce forest diagrams to represent elements of Thompson's group F. These diagrams relate to a certain action of F on the real line in the same way that tree diagrams relate to the standard action of F on the unit interval. Using…

Group Theory · Mathematics 2018-10-30 James M. Belk , Kenneth S. Brown

Let F be the (Thompson's) group < x_0, x_1 | [x_0x_1^-1, x_0^-ix_1 x_0^i], i=1,2 >. We study the structure of F-limit groups. Let G_n= < y_1,..., y_m, x_0,x_1 | [x_0x_1^-1,x_0^-1x_1x_0],[x_0x_1^-1,x_0^-2x_1x_0^2], y_j^-1g_j,n(x_0,x_1),…

Group Theory · Mathematics 2013-08-30 Roland Zarzycki

We show that the free group of rank 2 is a limit of 2-markings of Thompson's group F in the space of all 2-marked groups. More specifically, we find a sequence of generating pairs for F so that as one goes out the sequence, the length of…

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

The arguments of Cannon, Floyd, Grayson and Thurston showing that solve geometry groups are not almost convex also show that solvable Baumslag-Solitar groups are not almost convex.

Group Theory · Mathematics 2008-02-03 Charles Miller , Michael Shapiro

We provide a new upper bound for the length for the shortest non-trivial element in the lower central series $\gamma_n(\mathbb{F}_2)$ of the free group on two generators. We prove that it has an asymptotic behaviour of the form…

Group Theory · Mathematics 2016-11-01 Abdelrhman Elkasapy

Every finite simple group can be generated by two elements and, in fact, every nontrivial element is contained in a generating pair. Groups with this property are said to be $\frac{3}{2}$-generated, and the finite $\frac{3}{2}$-generated…

Group Theory · Mathematics 2023-07-14 Collin Bleak , Scott Harper , Rachel Skipper

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

It is a long standing open problem whether the Thompson group $F$ is an amenable group. In this paper we show that if $A$, $B$, $C$ denote the standard generators of Thompson group $T$ and $D:=C B A^{-1}$ then…

Group Theory · Mathematics 2018-09-25 S. Haagerup , U. Haagerup , M. Ramirez-Solano

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 Farley's CAT(0) cubical model for Thompson's group F (we adopt the classical language of F, using binary trees and piecewise linear maps). Main results include: in general, Thompson's group elements are parabolic; we find…

Group Theory · Mathematics 2012-03-27 Dan-Titus Salajan

We give the first examples of groups which admit a tame combing with linear radial tameness function with respect to any choice of finite presentation, but which are not minimally almost convex on a standard generating set. Namely, we…

Group Theory · Mathematics 2018-03-19 Sean Cleary , Susan Hermiller , Melanie Stein , Jennifer Taback

Brown has defined the generalised Thompson's group $F_n$, $T_n$, where $n$ is an integer at least $2$ and Thompson's groups $F= F_2$ and $T =T_2$ in the 80's. Burillo, Cleary and Stein have found that there is a quasi-isometric embedding…

Group Theory · Mathematics 2022-09-27 Xiaobing Sheng

In this paper it is proved that the group $F\left(\frac32\right)$, a Thompson-style group with breaks in $\mathbb{Z}\left[\frac16\right]$ but whose slopes are restricted only to powers of $\frac32$, is finitely generated, with a generating…

Group Theory · Mathematics 2024-09-17 José Burillo , Marc Felipe

We extend the concept of two-way forest diagrams, introduced by Belk and Brown in 2003, to represent elements of $F(n)$ as a pair of infinite, bounded $n$-ary forests together with an order-preserving bijection of the leaves. This…

Group Theory · Mathematics 2026-05-11 Martín Gómez Reynolds

We give an example of a Cayley graph $\Gamma$ for the group $F_{2}\times F_{2}$ which is not minimally almost convex (MAC). On the other hand, the standard Cayley graph for $F_{2}\times F_{2}$ does satisfy the falsification by fellow…

Group Theory · Mathematics 2024-06-07 Andrew Elvey Price