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We prove that for lambda = beta_omega or just lambda strong limit singular of cofinality aleph_0, if there is a universal member in the class K^lf_lambda of locally finite groups of cardinality lambda, then there is a canonical one…

Logic · Mathematics 2023-03-08 Saharon Shelah

The structure of automorphism groups of $\kappa$-existentially closed groups are studied by Kaya-Kuzucuo\u{g}lu in 2022. It was proved that Aut(G) is the union of subgroups of level preserving automorphisms and $|Aut(G)|=2^\kappa$ whenever…

Logic · Mathematics 2024-09-04 Burak Kaya , Mahmut Kuzucuoğlu , Patrizia Longobardi , Mercede Maj

In S. 1 we deal with amalgamation bases, e.g., we define when an a.e.c. $k$ has $(\lambda,\kappa)$-amalgamation which means "many" M in $K^k_\lambda$ are amalgamation bases. We then consider what happens for the class of lf groups. In S. 2…

Logic · Mathematics 2019-01-29 Saharon Shelah

We characterize the fundamental group of a locally finite graph G with ends combinatorially, as a group of infinite words. Our characterization gives rise to a canonical embedding of this group in the inverse limit of the (free) fundamental…

Combinatorics · Mathematics 2009-10-30 Reinhard Diestel , Philipp Sprüssel

The concept of an omnigenous locally finite group was introduced in [2] as a generalization of Hall's universal countable locally finite group. In this paper we show that the class of all countable omnigenous locally finite groups is Borel…

Logic · Mathematics 2025-09-17 Su Gao , Feng Li

We prove that infinite definably simple locally finite groups of finite centraliser dimension are simple groups of Lie type over locally finite fields. Then, we identify conditions on automorphisms of a stable group that make it resemble…

Logic · Mathematics 2019-06-12 Ulla Karhumäki

Strongly bounded groups are those groups for which every action by isometries on a metric space has orbits of finite diameter. Many groups have been shown to have this property, and all the known infinite examples so far have cardinality at…

Group Theory · Mathematics 2020-10-07 Samuel M. Corson , Saharon Shelah

Let $G$ be an infinite locally compact group and $\aleph$ a cardinal satisfying $\aleph_0\le\aleph\le w(G)$ for the weight $w(G)$ of $G$. It is shown that there is a closed subgroup $N$ of $G$ with $w(N)=\aleph$. Sample consequences are:…

Group Theory · Mathematics 2012-01-19 Salvador Hernández , Karl H. Hofmann , Sidney A. Morris

A locally compact contraction group is a pair (G,f) where G is a locally compact group and f an automorphism of G which is contractive in the sense that the forward orbit under f of each g in G converges to the neutral element e, as n tends…

Group Theory · Mathematics 2018-04-05 Helge Glockner , George A. Willis

We study algebraic and model-theoretic properties of existentially closed fields with an action of a fixed finite group. Such fields turn out to be pseudo-algebraically closed in a rather strong sense. We place this work in a more general…

Logic · Mathematics 2019-05-24 Daniel Max Hoffmann , Piotr Kowalski

Existentially closed groups are, informally, groups that contain solutions to every consistent finite system of equations and inequations. They were introduced in 1951 in an algebraic context and subsequent research elucidated deep…

Logic · Mathematics 2024-04-18 I Scott

We investigate the automorphisms of some $\kappa$- existentially closed groups. In particular, we prove that $Aut(G)$ is the union of subgroups of level preserving automorphisms and $|Aut(G)|=2^{\kappa}$ whenever $\kappa$ is inaccessible…

Group Theory · Mathematics 2021-01-01 Burak Kaya , Mahmut Kuzucuoğlu

We study the uniform Roe algebras associated to locally finite groups. We show that for two countable locally finite groups $\Gamma$ and $\Lambda$, the associated uniform Roe algebras $C^*_u(\Gamma)$ and $C^*_u(\Lambda)$ are $*$-isomorphic…

Operator Algebras · Mathematics 2017-05-11 Kang Li , Hung-Chang Liao

A finitely generated group $G$ is said to be condensed if its isomorphism class in the space of finitely generated marked groups has no isolated points. We prove that every product variety $\mathcal{UV}$, where $\mathcal{U}$ (respectively,…

Group Theory · Mathematics 2021-02-16 D. Osin

We introduce a new class of locally compact groups, namely the strongly compactly covered groups, which are the Hausdorff topological groups $G$ such that every element of $G$ is contained in a compact open normal subgroup of $G$. For…

General Topology · Mathematics 2018-05-25 Anna Giordano Bruno , Menachem Shlossberg , Daniele Toller

This is an introduction to the class of groups that are locally embeddable into finite groups.

Group Theory · Mathematics 2020-04-17 Melvyn B. Nathanson

We give a construction of a family of locally finite residually finite groups with just-infinite C*-algebra. This answers a question from [2]. Additionally, we show that residually finite groups of finite exponent are never just-infinite.

Operator Algebras · Mathematics 2016-06-27 V. Belyaev , R. Grigorchuk , P. Shumyatsky

We discuss the finiteness of the topological entropy of continuous endomorphims for some classes of locally compact groups. Firstly, we focus on the abelian case, imposing the condition of being compactly generated, and note an interesting…

Group Theory · Mathematics 2024-03-01 Francesco G. Russo , Olwethu Waka

A group homomorphism eta:H-->G is called a localization of H if every homomorphism phi:H-->G can be `extended uniquely' to a homomorphism Phi:G-->G in the sense that Phi eta=phi. Libman showed that a localization of a finite group need not…

Logic · Mathematics 2007-05-23 Ruediger Goebel , Jose L. Rodriguez , Saharon Shelah

We study algebraic properties on a group G such that if the discrete group G has these properties then every locally compact shift continuous topology on G with adjoined zero is either compact, or discrete. We introduce electorally flexible…

Group Theory · Mathematics 2020-06-30 Kateryna Maksymyk
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