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It is shown that a closed solvable subgroup of a connected Lie group is compactly generated. In particular, every discrete solvable subgroup of a connected Lie group is finitely generated. Generalizations to locally compact groups are…

Group Theory · Mathematics 2011-02-19 Karl Heinrich Hofmann , Karl-Hermann Neeb

We prove a Mackey formula for representations of finite groups of Lie type, in the case where the groups come from disconnected reductive groups.

Representation Theory · Mathematics 2024-03-21 Sergio Cía

We study verbally closed subgroups of free solvable groups. A number of results is proved that give sufficient conditions under whose a verbally closed subgroup is turned to be a retract and so algebraically closed of the full group.

Group Theory · Mathematics 2019-06-28 V. A. Roman'kov , E. I. Timoshenko

The purpose of this paper is to extend some useful results, such as the multiplication being open, previously known for suitable finitely generated relatively free profinite semigroups, to relatively free profinite semigroupoids over…

Group Theory · Mathematics 2025-07-14 Jorge Almeida , Alfredo Costa , Herman Goulet-Ouellet

We study subsets of groups and monoids defined by language-theoretic means, generalizing the classical approach to the word problem. We expand on results by Herbst from 1991 to a more general setting, and for a class of languages…

Group Theory · Mathematics 2025-04-01 André Carvalho , Carl-Fredrik Nyberg-Brodda

We introduce the notion of a ``sofic $\mathcal{C}$-action'' of one group on another by automorphisms, for $\mathcal{C}$ a class of groups. We show that if $\mathcal{C}$ is the class of (i) sofic, (ii) hyperlinear, (iii) linear sofic or (iv)…

Group Theory · Mathematics 2026-01-27 Vadim Alekseev , Henry Bradford

We first establish several general properties of modality of algebraic group actions. In particular, we introduce the notion of a modality-regular action and prove that every visible action is modality-regular. Then, using these results, we…

Representation Theory · Mathematics 2017-07-26 Vladimir L. Popov

We study equicontinuous actions of semisimple groups and some generalizations. We prove that any such action is universally closed, and in particular proper. We derive various applications, both old and new, including closedness of…

Group Theory · Mathematics 2017-06-16 Uri Bader , Tsachik Gelander

We give a new, simple proof of the trace formula for Hecke operators on modular forms for finite index subgroups of the modular group. The proof uses algebraic properties of certain universal Hecke operators acting on period polynomials of…

Number Theory · Mathematics 2017-06-09 Alexandru A. Popa

The study of verbal subgroups within a group is well-known for being an effective tool to obtain structural information about a group. Therefore, conditions that allow the classification of words in a free group are of paramount importance.…

Group Theory · Mathematics 2025-11-03 Costantino Delizia , Michele Gaeta , Carmine Monetta

The notion of an open quantum subgroup of a locally compact quantum group is introduced and given several equivalent characterizations in terms of group-like projections, inclusions of quantum group C*-algebras and properties of respective…

Operator Algebras · Mathematics 2016-08-15 Mehrdad Kalantar , Paweł Kasprzak , Adam Skalski

We generalize a result by Cunningham-Salmasian to a Mackey-type formula for the compact restriction of a semisimple perverse sheaf produced by parabolic induction from a character sheaf, under certain conditions on the parahoric group used…

Representation Theory · Mathematics 2010-11-09 Pramod N. Achar , Clifton L. R. Cunningham

We generalize a result of Hochman in two simultaneous directions: Instead of realizing an effectively closed $\mathbb{Z}^d$ action as a factor of a subaction of a $\mathbb{Z}^{d+2}$-SFT we realize an action of a finitely generated group…

Dynamical Systems · Mathematics 2019-04-26 Sebastián Barbieri , Mathieu Sablik

We extend Dwyer's sharp subgroup homology decomposition of the classifying space of a finite group to arbitrary saturated fusion systems and arbitrary Mackey functors.

Algebraic Topology · Mathematics 2015-09-04 Antonio Díaz , Sejong Park

The known facts about solvability of equations over groups are considered from a more general point of view. A generalized version of the theorem about solvability of unimodular equations over torsion-free groups is proved. In a special…

Group Theory · Mathematics 2007-05-23 Anton A. Klyachko

The article $-$ part of a larger thesis which aims to give a detailed description of the generalisation to the category of groups with operators of the classical theory of semisimplicity for modules $-$ presents a straightforward…

Group Theory · Mathematics 2020-12-15 Sebastian Cristian Lesnic

We prove an entropy formula for certain expansive actions of a countable discrete residually finite group $\Gamma $ by automorphisms of compact abelian groups in terms of Fuglede-Kadison determinants. This extends an earlier result proved…

Dynamical Systems · Mathematics 2007-05-23 Christopher Deninger , Klaus Schmidt

Definition of a smooth action of a CQG on a compact, smooth manifold is given and studied. It is shown that a smooth action is always injective. Furthermore A necessary and sufficient condition for a lift of the smooth action as a bimodule…

Quantum Algebra · Mathematics 2015-07-31 Debashish Goswami , Soumalya Joardar

An elementary proof is given for the fact that every locally compact subsemigroup of a compact topological group is a closed subgroup. A sample consequence is that every commutative cancellative pseudocompact locally compact Hausdorff…

General Topology · Mathematics 2020-10-13 Julio César Hernández Arzusa

An implicit operation of a class of similar algebras $\mathsf{K}$ is a collection of first order definable partial functions on the members of $\mathsf{K}$ that is globally preserved by homomorphisms. For instance, "taking inverses" can be…

Rings and Algebras · Mathematics 2026-03-17 Luca Carai , Miriam Kurtzhals , Tommaso Moraschini