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A group is small if it has countably many complete $n$-types over the empty set for each natural number n. More generally, a group $G$ is weakly small if it has countably many complete 1-types over every finite subset of G. We show here…

Logic · Mathematics 2019-03-01 Cédric Milliet

We study groups having the property that every non-cyclic subgroup contains its centralizer. The structure of nilpotent and supersolvable groups in this class is described. We also classify finite $p$-groups and finite simple groups with…

Group Theory · Mathematics 2014-01-28 Costantino Delizia , Urban Jezernik , Primož Moravec , Chiara Nicotera

It is important to classify covering subgroups of the fundamental group of a topological space using their topological properties in the topologized fundamental group. In this paper, we introduce and study some topologies on the fundamental…

Algebraic Topology · Mathematics 2018-07-04 M. Ab dullahi Rashid , N. Jamali , B. Mashayekhy , S. Z. Pashaei , H. Torabi

We study universal groups for right-angled buildings. Inspired by Simon Smith's work on universal groups for trees, we explicitly allow local groups that are not necessarily finite nor transitive. We discuss various topological and…

Group Theory · Mathematics 2021-01-28 Jens Bossaert , Tom De Medts

We introduce the coherent algebra of a compact metric measure space by analogy with the corresponding concept for a finite graph. As an application we show that upon topologizing the collection of isomorphism classes of compact metric…

Operator Algebras · Mathematics 2018-12-04 Alexandru Chirvasitu

A finite group G is said to be a cut group if all central units in the integral group ring ZG are trivial. In this article, we extend the notion of cut groups, by introducing extended cut groups. We study the properties of extended cut…

Group Theory · Mathematics 2025-03-21 Àngel García-Blàzquez , Gurleen Kaur , Sugandha Maheshwary

A closed subgroup of a semisimple algebraic group is called irreducible if it lies in no proper parabolic subgroup. In this paper we classify all irreducible subgroups of exceptional algebraic groups $G$ which are connected, closed and…

Group Theory · Mathematics 2022-09-22 Adam Thomas

We describe certain almost-simple algebraic supergroups over an algebraically closed field of odd or zero characteristic. In addition to supergroups with simple Lie superalgebras from Kac's theorem, we construct new supergroups whose Lie…

Rings and Algebras · Mathematics 2025-11-21 S. Bouarroudj , A. N. Zubkov

Let $G$ be a subgroup of a discrete (countable) group $\Gamma$. We introduce a notion of relative inner amenability of $G$ in $\Gamma$, we prove some equivalent conditions and provide examples as well as counter-examples. We also discuss…

Group Theory · Mathematics 2013-12-03 Paul Jolissaint

A common fixed point property for semigroups is applied to show that the group algebra $L^1(G)$ of a locally compact group $G$ is $2m$-weakly amenable for each integer $m\geq 1$.

Functional Analysis · Mathematics 2012-07-20 Yong Zhang

In this paper, we are interested in study subgroups of topologized fundamental groups and their influences on generalized covering maps. More precisely, we find some relationships between generalized covering subgroups and the other famous…

Algebraic Topology · Mathematics 2016-02-26 Mehdi Abdullahi Rashid , Behrooz Mashayekhy , Hamid Torabi , Seyyed Zeynal Pashaei

We consider the class of finitely generated groups which have a normal form computable in logspace. We prove that the class of such groups is closed under finite extensions, finite index subgroups, direct products, wreath products, and also…

Group Theory · Mathematics 2014-01-28 Murray Elder , Gillian Elston , Gretchen Ostheimer

In this paper we look into the structure of finite-dimensional graded superalgebras of various types such as associative, Lie and Jordan over an algebraically closed field of characteristic zero.

Rings and Algebras · Mathematics 2007-09-13 M. Tvalavadze , T. Tvalavadze

We investigate classifications of quasitrivial semigroups defined by certain equivalence relations. The subclass of quasitrivial semigroups that preserve a given total ordering is also investigated. In the special case of finite semigroups,…

Rings and Algebras · Mathematics 2020-05-21 Jimmy Devillet , Jean-Luc Marichal , Bruno Teheux

The goal of this note is to classify the weakly closed unipotent subgroups in the split Chevalley groups. In an application we show under some mild assumptions on the characteristic that the Lie algebra of a connected simple algebraic group…

Group Theory · Mathematics 2007-05-23 R. Guralnick , G Roehrle

We describe a class (called regular) of invariant generalized complex structures on a real semisimple Lie group G. The problem reduces to the description of admissible pairs (\gk, \omega), where \gk is an appropriate regular subalgebra of…

Differential Geometry · Mathematics 2014-02-26 Dmitri V. Alekseevsky , Liana David

We consider a convenient category of "quadratic" multirings, that allows simple functorial relations with categories associated with abstract quadratic forms theories and shares many good aspects of the theories of Special Groups and of…

Rings and Algebras · Mathematics 2017-03-30 Kaique Matias de Andrade Roberto , Hugo Rafael Ribeiro , Hugo Luiz Mariano

We present a new notion of non-positively curved groups: the collection of discrete countable groups acting (AU-)acylindrically on finite products of $\delta$-hyperbolic spaces with general type factors. Inspired by the classical theory of…

Group Theory · Mathematics 2025-12-30 Sahana Balasubramanya , Talia Fernos

Motivated by intuitive properties of physical quantities, the notion of a non-anomalous semigroup is formulated. These are totally ordered semigroups where there are no `infinitesimally close' elements. The real numbers are then defined as…

History and Overview · Mathematics 2016-07-21 Damon Binder

In many instances in first order logic or computable algebra, classical theorems show that many problems are undecidable for general structures, but become decidable if some rigidity is imposed on the structure. For example, the set of…

Discrete Mathematics · Computer Science 2017-08-08 Emmanuel Jeandel