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Let A denote the algebraic closure of the rationals Q in the complex numbers C. Suppose G is a torsion-free group which contains a congruence subgroup as a normal subgroup of finite index and denote by U(G) the C-algebra of closed densely…

Rings and Algebras · Mathematics 2007-05-23 Daniel R. Farkas , Peter A. Linnell

Given a reflection $r$ in a Coxeter group $W$ (possibly of infinite rank), we consider the subgroup of $W$ generated by the reflections in $W$ having (-1)-eigenvectors orthogonal to the (-1)-eigenvector of $r$. In this paper, we determine…

Group Theory · Mathematics 2012-01-18 Koji Nuida

A one-relator group with lower central series of length \omega^2 is constructed. This answers a problem of G. Baumslag.

Group Theory · Mathematics 2014-06-11 Roman Mikhailov

Given a group-word w and a group G, the verbal subgroup w(G) is the one generated by all w-values in G. The word w is said to be concise if w(G) is finite whenever the set of w-values in G is finite. In the sixties P. Hall asked whether…

Group Theory · Mathematics 2017-11-21 Eloisa Detomi , Marta Morigi , Pavel Shumyatsky

Let $\Gamma$ be a finitely generated cocompact lattice of a totally disconnected locally compact group $G$, and $C$ a dense subgroup of $G$ that contains and commensurates $\Gamma$. We study the problem of describing all finitely generated…

Group Theory · Mathematics 2026-04-08 Adrien Le Boudec , Colin Reid

We prove a freeness theorem for low-rank subgroups of one-relator groups. Let $F$ be a free group, and let $w\in F$ be a non-primitive element. The primitivity rank of $w$, $\pi(w)$, is the smallest rank of a subgroup of $F$ containing $w$…

Group Theory · Mathematics 2021-05-07 Larsen Louder , Henry Wilton

We extend several results of Helfer, Wise, Louder and Wilton related to coherence in one-relator groups to the more general setting of one-relator products of locally indicable groups. The methods developed to do so also give rise to a new…

Group Theory · Mathematics 2025-07-15 James Howie , Hamish Short

We construct finitely generated simple torsion-free groups with strong homological control. Our main result is that every subset of $\mathbb{N} \cup \{\infty\}$, with some obvious exceptions, can be realized as the set of dimensions of…

Group Theory · Mathematics 2025-04-14 Francesco Fournier-Facio , Bin Sun

Adding two generators and one arbitrary relator to a nontrivial torsion-free group, we always obtain an SQ-universal group. In the course of the proof of this theorem, we obtain some other results of independent interest. For instance,…

Group Theory · Mathematics 2007-07-29 Anton A. Klyachko

Conjugacy separability of any group of the class of one-relator groups given by the presentation $<a, b; [a^m,b^n]=1>$ ($m,n>1$) is proven.

Group Theory · Mathematics 2007-05-23 D. Tieudjo , D. I. Moldavanskii

We exhibit finitely generated torsion-free groups for which any action on any finite-dimensional CW-complex with finite Betti numbers has a global fixed point.

Group Theory · Mathematics 2025-09-25 Nansen Petrosyan

The general {\bf surface group conjecture} asks whether a one-relator group where every subgroup of finite index is again one-relator and every subgroup of infinite index is free (property IF) is a surface group. We resolve several related…

Group Theory · Mathematics 2012-08-21 Laura Ciobanu , Ben Fine , Gerhard Rosenberger

Suppose that G is a nontrivial torsion-free group and w is a word over the alphabet G\cup\{x_1^{\pm1},...,x_n^{\pm1}\}. It is proved that for n\ge2 the group \~G=<G,x_1,x_2,...,x_n | w=1> always contains a nonabelian free subgroup. For n=1…

Group Theory · Mathematics 2007-09-02 Anton A. Klyachko

We prove that the word problem for the infinite cyclic group is not EDT0L, and obtain as a corollary that a finitely generated group with EDT0L word problem must be torsion. In addition, we show that the property of having an EDT0L word…

Group Theory · Mathematics 2026-01-21 Alex Bishop , Murray Elder , Alex Evetts , Paul Gallot , Alex Levine

Motivated by the notion of boundary for hyperbolic and $CAT(0)$ groups, M. Bestvina in "Local Homology Properties of Boundaries of Groups" introduced the notion of a (weak) $\mathcal Z$-structure and (weak) $\mathcal Z$-boundary for a group…

Geometric Topology · Mathematics 2022-07-20 M. Cárdenas , F. F. LasHeras , A. Quintero

A word $w$ is said to be concise in a class of groups if, for every $G$ in that class such that the set of $w$-values $w\{G\}$ is finite, the verbal subgroup $w(G)$ is also finite. In the context of profinite groups, the notion of strong…

Group Theory · Mathematics 2025-02-12 Iker de las Heras , Andoni Zozaya

The goal of this note is to provide yet another proof of the following theorem of Golod: there exists an infinite finitely generated group $G$ such that every element of $G$ has finite order. Our proof is based on the Nielsen-Schreier index…

Group Theory · Mathematics 2023-06-02 D. Osin

We link distinct concepts of geometric group theory and homotopy theory through underlying combinatorics. For a flag simplicial complex $K$, we specify a necessary and sufficient combinatorial condition for the commutator subgroup $RC_K'$…

Algebraic Topology · Mathematics 2023-06-22 Jelena Grbić , Marina Ilyasova , Taras Panov , George Simmons

We study a characteristic subgroup of finitely generated groups, consisting of elements with uniform upper bound for word-lengths. For a group $G$, we denote this subgroup by $G_{bound}$. We give sufficient criteria for triviality and…

Group Theory · Mathematics 2021-02-23 Yanis Amirou

We show that the finitely generated simple left orderable groups $G_{\rho}$ constructed by the first two authors in arXiv:1807.06478 are uniformly perfect - each element in the group can be expressed as a product of three commutators of…

Group Theory · Mathematics 2020-11-25 James Hyde , Yash Lodha , Andrés Navas , Cristóbal Rivas