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Let $G$ be a finite group and let $p$ be a prime. We continue the search for generic constructions of free products and free monoids in the unit group $\mathcal{U}(\mathbb{Z}G)$ of the integral group ring $\mathbb{Z}G$. For a nilpotent…

Rings and Algebras · Mathematics 2020-03-26 Geoffrey Janssens , Eric Jespers , Doryan Temmerman

In this paper, we introduce the notion of $L^2$-subgroup rigid groups and demonstrate that free groups are $L^2$-subgroup rigid. As a consequence, we establish the equivalence between compressibility, inertness, strong inertness, and…

Group Theory · Mathematics 2026-02-05 Andrei Jaikin-Zapirain

In this paper, we study the so-called diagram groups. Our main result is that diagram groups are free if and only if they do not contain any subgroup isomorphic to $\mathbb{Z}^2$. As an immediate corollary, we get that hyperbolic diagram…

Group Theory · Mathematics 2015-05-11 Anthony Genevois

We present a procedure of group cubization: It results in a group whose some features resemble the ones of a given group, and which acts without fixed points on a CAT(0) cubical complex. As a main application we establish lack of Kazhdan's…

Group Theory · Mathematics 2018-05-23 Damian Osajda

We show that every right-angled Artin group AG defined by a graph G of finite chromatic number is poly-free with poly-free length bounded between the clique number and the chromatic number of G. Further, a characterization of all…

Group Theory · Mathematics 2007-05-23 Susan Hermiller , Zoran Sunik

We prove that the outer automorphism group of a free group of countably infinite rank is complete.

Group Theory · Mathematics 2025-05-20 Vladimir A. Tolstykh

We prove that a CAT(0) free-by-cyclic tubular group with one vertex is virtually special, but many of them cannot virtually act freely and cocompactly on CAT(0) cube complexes. This partially confirms a question of Brady--Soroko…

Group Theory · Mathematics 2025-04-22 Xiaolei Wu , Shengkui Ye

We show that if $G$ is a non-archimedean, Roelcke precompact, Polish group, then $G$ has Kazhdan's property (T). Moreover, if $G$ has a smallest open subgroup of finite index, then $G$ has a finite Kazhdan set. Examples of such $G$ include…

Group Theory · Mathematics 2015-09-03 David M. Evans , Todor Tsankov

A $k$-free like group is a $k$-generated group $G$ with a sequence of $k$-element generating sets $Z_n$ such that the girth of $G$ relative to $Z_n$ is unbounded and the Cheeger constant of $G$ relative to $Z_n$ is bounded away from 0. By a…

Group Theory · Mathematics 2008-11-12 A. Yu. Olshanskii , M. V. Sapir

Let ${\bf F}$ be a field of characteristic zero. It is proved that for any finitely generated linear group $\Gamma<\mathsf{GL}_n({\bf F})$, every unipotent-free abelian subgroup of $\Gamma$ is separable.

Group Theory · Mathematics 2025-04-29 Konstantinos Tsouvalas

In this paper we start the inquiry into proving uniform exponential growth in the context of groups acting on CAT(0) cube complexes. We address free group actions on CAT(0) square complexes and prove a more general statement. This says that…

Group Theory · Mathematics 2019-05-29 Aditi Kar , Michah Sageev

We describe an effective procedure to compute the local subgroup zeta functions of the free class-$2$-nilpotent groups on $d$ generators, for all $d$. For $d=4$, this yields a new, explicit formula. For $d\in\{4,5\}$, we compute the…

Group Theory · Mathematics 2024-11-05 Viola Siconolfi , Marlies Vantomme , Christopher Voll

We study the free complexification operation for compact quantum groups, $G\to G^c$. We prove that, with suitable definitions, this induces a one-to-one correspondence between free orthogonal quantum groups of infinite level, and free…

Quantum Algebra · Mathematics 2008-11-02 Teodor Banica

We prove that no infinite field is definable in the theory of the free group

Logic · Mathematics 2015-12-29 Ayala Byron , Rizos Sklinos

We show that compact complex manifolds of algebraic dimension zero bearing a holomorphic Cartan geometry of algebraic type have infinite fundamental group. This generalizes the main Theorem in [DM] where the same result was proved for the…

Differential Geometry · Mathematics 2019-12-03 Indranil Biswas , Sorin Dumitrescu , Benjamin McKay

We characterize finitely generated torsion-free Kleinian groups for which the real length spectrum (without multiplicities) is discrete.

Geometric Topology · Mathematics 2007-05-23 Richard D. Canary , Christopher J. Leininger

A Lie algebra L is known to be nilpotent if it admits a grading by (Zp, +) with support X not containing 0. It is also known that the class of L can be bounded by some explicit function of |X|. We generalise this and other classical results…

Rings and Algebras · Mathematics 2016-08-04 Wolfgang Alexander Moens

We will show that if a proper complete CAT(0) space X has a visual boundary homeomorphic to the join of two Cantor sets, and X admits a geometric group action by a group containing a subgroup isomorphic to Z^2, then its Tits boundary is the…

Metric Geometry · Mathematics 2014-10-01 Khek Lun Harold Chao

We investigate free product structures in R. Thompson's group V, primarily by studying the topological dynamics associated with V's action on the Cantor Set. We show that the class of free products which can be embedded into V includes the…

Group Theory · Mathematics 2009-11-06 Collin Bleak , Olga Salazar-Diaz

In this paper we consider the palindromic width of free nilpotent groups. In particular, we prove that the palindromic width of a finitely generated free nilpotent group is finite. We also prove that the palindromic width of a free…

Group Theory · Mathematics 2014-02-25 Valeriy G. Bardakov , Krishnendu Gongopadhyay