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We construct irreducible unitary representations of a finitely generated free group which are weakly contained in the left regular representation and in which a given linear combination of the generators has an eigenvalue. When the…

Operator Algebras · Mathematics 2007-05-23 William L. Paschke

Let $G$ be $S_{\mathbb{N}}$, the finitary permutation (i.e. permutations with finite support) group on positive integers $\mathbb{N}$. We prove that $G$ has the invariant von Neumann subalgebras rigidity (ISR, for short) property as…

Operator Algebras · Mathematics 2024-04-04 Yongle Jiang , Xiaoyan Zhou

In $2019$ Hyde and the second author constructed the first family of finitely generated, simple, left orderable groups. We prove that these groups are not finitely presentable, non-inner amenable, don't have Kazhdan's property $(T)$ (yet…

Group Theory · Mathematics 2025-09-15 Pawel Aleksander Fedorynski , Yash Lodha

A group is metabelian if its commutator subgroup is abelian. For finitely generated metabelian groups, classical commutative algebra, algebraic geometry and geometric group theory, especially the latter two subjects, can be brought to bear…

Group Theory · Mathematics 2012-03-27 Gilbert Baumslag , Roman Mikhailov , Kent E. Orr

By classifying $S$-maximal amenable subgroups of algebraic groups over a global field of characteristic zero, we obtain a complete classification of maximal amenable subgroups up to commensurability in the respective arithmetic groups.…

Group Theory · Mathematics 2022-10-21 Vadim Alekseev , Alessandro Carderi

Let $R$ be a ring, let $G$ be an amenable group and let $R\ast G$ be a crossed product. The goal of this paper is to construct, starting with a suitable additive function $L$ on the category of left modules over $R$, an additive function on…

Rings and Algebras · Mathematics 2017-10-24 Simone Virili

We say that a finite group $G$ satisfies the independence property if, for every pair of distinct elements $x$ and $y$ of $G$, either $\{x,y\}$ is contained in a minimal generating set for $G$ or one of $x$ and $y$ is a power of the other.…

Group Theory · Mathematics 2023-05-30 Saul D. Freedman , Andrea Lucchini , Daniele Nemmi , Colva M. Roney-Dougal

For a torsion free finitely generated nilpotent group G we naturally associate four finite dimensional nilpotent Lie algebras over a field of characteristic zero. We show that if G is a relatively free group of some variery of nilpotent…

Group Theory · Mathematics 2009-03-10 C. Kofinas , V. Metaftsis , A. I. Papistas

We show that, if $H$ is a random subgroup of a finitely generated free group $F_k$, only inner automorphisms of $F_k$ may leave $H$ invariant. A similar result holds for random subgroups of toral relatively hyperbolic groups, more generally…

Group Theory · Mathematics 2019-06-26 Vincent Guirardel , Gilbert Levitt

For any countable torsion subgroup $H$ of an unbounded Abelian group $G$ there is a complete Hausdorff group topology $\tau$ such that $H$ is the von Neumann radical of $(G,\tau)$. In particular, any unbounded torsion countable Abelian…

Group Theory · Mathematics 2010-02-07 S. S. Gabriyelyan

In [9] we proved that the space of countable torsion-free abelian groups is Borel complete. In this paper we show that our construction from [9] satisfies several additional properties of interest. We deduce from this that countable…

Logic · Mathematics 2026-01-27 Gianluca Paolini , Saharon Shelah

Let $G$ be a group and $H\leqslant G$ a subgroup. The free extension of an $H$-subshift $X$ to $G$ is the $G$-subshift $\widetilde{X}$ whose configurations are those for which the restriction to every coset of $H$ is a configuration from…

Dynamical Systems · Mathematics 2025-02-25 Sebastián Barbieri , Mathieu Sablik , Ville Salo

We provide new examples of $\mathrm{C}^*$-selfless groups and inclusions. In particular, we prove that the commensurator group ${\rm Comm}(H)$ of a torsion-free hyperbolic group $H$ is $\mathrm{C}^*$-selfless. Our approach involves showing…

Group Theory · Mathematics 2026-05-14 Aaratrick Basu , Felipe Flores

An $integral$ of a group $G$ is a group $H$ whose commutator subgroup is isomorphic to $G$. This paper continues the investigation on integrals of groups started in the work arXiv:1803.10179. We study: (1) A sufficient condition for a bound…

Group Theory · Mathematics 2024-05-29 João Araújo , Peter J. Cameron , Carlo Casolo , Francesco Matucci , Claudio Quadrelli

We study gradings by noncommutative groups on finite dimensional Lie algebras over an algebraically closed field of characteristic zero. It is shown that if $L$ is gradeg by a non-abelian finite group $G$ then the solvable radical $R$ of…

Rings and Algebras · Mathematics 2016-02-19 Dušan Pagon , Dušan Repovš , Mikhail Zaicev

Utilizing an embedding theorem of Obraztsov we construct groups as described in the title. This provides an affirmative answer to a problem of D. O. Revin. The constructed groups also provide a negative answer to a question highlighted by…

Group Theory · Mathematics 2025-06-23 Samuel M. Corson

For any topological group $G$ the dual object $\hat G$ is defined as the set of equivalence classes of irreducible unitary representations of $G$ equipped with the Fell topology. If $G$ is compact, $\hat G$ is discrete, and we investigate…

General Topology · Mathematics 2021-08-30 M. Ferrer , S. Hernández , V. Uspenskij

Let $G$ be a finite solvable group. Then $G$ always has a useful presentation, which we call a "long presentation". Using a "long presentation" of $G$, we present an inductive method of constructing the irreducible representations of $G$…

Representation Theory · Mathematics 2018-10-11 Ravi S. Kulkarni , Soham Swadhin Pradhan

We construct first examples of infinite groups having property (T) whose Kazhdan constants admit a lower bound independent of the choice of a finite generating set.

Group Theory · Mathematics 2007-05-23 D. Osin , D. Sonkin

We classify finitely generated, residually finite automorphism-induced HNN-extensions in terms of the residual separability of a single associated subgroup. This classification provides a method to construct automorphism-induced…

Group Theory · Mathematics 2018-10-25 Alan D. Logan