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We construct free Lie algebras which, together with the algebra of spatial rotations, form infinite-dimensional extensions of finite-dimensional Galilei Maxwell algebras appearing as global spacetime symmetries of extended non-relativistic…

High Energy Physics - Theory · Physics 2020-06-23 Joaquim Gomis , Axel Kleinschmidt , Jakob Palmkvist

Given a variety of universal algebras. A method is suggested for describing automorphisms of a category of free algebras of this variety. Applying this general method all automorphisms of such categories are found in two cases: 1) for the…

Rings and Algebras · Mathematics 2007-05-23 Boris Plotkin , Grigori Zhitomirski

We establish a combination theorem for parafree groups. These groups were introduced by Baumslag in the sixties. One of the current motivations for a better understanding of their structure is that they show up naturally in connection with…

Group Theory · Mathematics 2024-03-04 Andrei Jaikin-Zapirain , Ismael Morales

We introduce separability properties corresponding to generalized versions of the conjugacy, twisted conjugacy, Brinkmann and Brinkmann's conjugacy problems and how they relate when finite and cyclic extensions of groups are taken. In…

Group Theory · Mathematics 2025-02-03 André Carvalho

The article gives the second part of the treatise on Regular Algebraic $K$-theory (Sections V & VI) of the author. Regular algebraic $K$-theory for groups is a homology theory for discrete groups closely connected to (but different from)…

K-Theory and Homology · Mathematics 2024-10-11 Ulrich Haag

In this paper we present a new characterization of free group actions (in classical differential geometry), involving dynamical systems and representations of the corresponding transformation groups. In fact, given a dynamical system, we…

Differential Geometry · Mathematics 2025-12-24 Stefan Wagner

In the present paper we develop a small cancellation theory for associative algebras with a basis of invertible elements. Namely, we study quotients of a group algebra of a free group and introduce three axioms for the corresponding…

Rings and Algebras · Mathematics 2024-01-17 A. Atkarskaya , A. Kanel-Belov , E. Plotkin , E. Rips

We study graphs of (generalized) joins and intersections of finitely generated subgroups of a free group. We show how to disprove a lemma of Imrich and M\"uller on these graphs and how to repair this lemma.

Group Theory · Mathematics 2016-07-19 Sergei V. Ivanov

These are lecture notes on the algebraic approach to regular languages. The classical algebraic approach is for finite words; it uses semigroups instead of automata. However, the algebraic approach can be extended to structures beyond…

Formal Languages and Automata Theory · Computer Science 2020-08-27 Mikołaj Bojańczyk

Given a complex semisimple Lie algebra ${\mathfrak g}$ and a commutative ${\mathbb C}$-algebra $A$, let ${\mathfrak g}[A] = {\mathfrak g} \otimes A$ be the corresponding generalized current algebra. In this paper we explore questions…

Representation Theory · Mathematics 2015-11-03 Brian D. Boe , Christopher M. Drupieski , Tiago R. Macedo , Daniel K. Nakano

We give a self-contained introduction to linear algebraic and semialgebraic groups over real closed fields, and we generalize several key results about semisimple Lie groups to algebraic and semialgebraic groups over real closed fields. We…

Group Theory · Mathematics 2026-01-13 Raphael Appenzeller

The main result of this article is a refinement of the well-known subgroup separability results of Hall and Scott for free and surface groups. We show that for any finitely generated subgroup, there is a finite dimensional representation of…

Group Theory · Mathematics 2018-11-14 Larsen Louder , D. B. McReynolds , Priyam Patel

We initiate the study of torsion-free algebraically hyperbolic groups; these groups generalise torsion-free hyperbolic groups and are intricately related to groups with no Baumslag--Solitar subgroups. Indeed, for groups of cohomological…

Group Theory · Mathematics 2025-04-29 Giles Gardam , Dawid Kielak , Alan D. Logan

We show the existence of and explicitly construct generic polynomials for various groups, over fields of positive characteristic. The methods we develop apply to a broad class of connected linear algebraic groups defined over finite fields…

Number Theory · Mathematics 2016-01-19 Eric Y. Chen , J. T. Ferrara , Liam Mazurowski

We give a complete classification of finitely generated virtually free groups up to $\forall\exists$-elementary equivalence. As a corollary, we give an algorithm that takes as input two finite presentations of virtually free groups, and…

Group Theory · Mathematics 2019-10-21 Simon André

We describe the development of the theory of automatic groups. We begin with a historical introduction, define the concepts of automatic, biautomatic and combable groups, derive basic properties, then explain how hyperbolic groups and the…

Group Theory · Mathematics 2022-05-31 Sarah Rees

By analogy with the classical construction due to Forrest, Samei and Spronk we associate to every compact quantum group $\mathbb{G}$ a completely contractive Banach algebra $A_\Delta(\mathbb{G})$, which can be viewed as a deformed Fourier…

Operator Algebras · Mathematics 2016-09-29 Uwe Franz , Hun Hee Lee , Adam Skalski

The survey contains a brief description of the ideas, constructions, results, and prospects of the theory of hypergroups and generalized translation operators. Representations of hypergroups are considered, being treated as continuous…

Representation Theory · Mathematics 2011-09-30 Grigory L. Litvinov

We indicate a natural generalization of the concept of subgroup commutativity degree of a finite group and a list of open problems on these new concepts.

Group Theory · Mathematics 2018-06-01 Marius Tărnăuceanu

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