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Related papers: On embeddings into compactly generated groups

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We describe the global structure of totally disconnected locally compact groups having a linear open compact subgroup. Among the applications, we show that if a non-discrete, compactly generated, topologically simple, totally disconnected…

Group Theory · Mathematics 2019-01-17 Pierre-Emmanuel Caprace , Thierry Stulemeijer

We present a contribution to the structure theory of locally compact groups. The emphasis is on compactly generated locally compact groups which admit no infinite discrete quotient. It is shown that such a group possesses a characteristic…

Group Theory · Mathematics 2012-07-10 Pierre-Emmanuel Caprace , Nicolas Monod

Wreath products of non-discrete locally compact groups are usually not locally compact groups, nor even topological groups. We introduce a natural extension of the wreath product construction to the setting of locally compact groups. As an…

Group Theory · Mathematics 2019-07-10 Yves Cornulier

We investigate what it means for a (Hausdorff, second-countable) topological group to be computable. We compare several potential definitions in the literature. We relate these notions with the well-established definitions of effective…

Logic · Mathematics 2025-04-16 Heer Tern Koh , Alexander Melnikov , Keng Meng Ng

In the last years, there has been a large amount of research on embeddability properties of finitely generated hyperbolic groups. In this paper, we elaborate on the more general class of locally compact hyperbolic groups. We compute the…

Group Theory · Mathematics 2014-06-23 Dennis Dreesen , Chris Cave

We construct a locally compact groupoid with the properties in the title. Our example is based closely on constructions used by Higson, Lafforgue, and Skandalis in their work on counterexamples to the Baum-Connes conjecture. It is a bundle…

Operator Algebras · Mathematics 2015-05-25 Rufus Willett

We investigate whether semigroups with a given property which are also locally embeddable into finite semigroups can be locally embedded into finite semigroups with the same property, obtaining a positive answer for completely simple and…

Group Theory · Mathematics 2025-10-27 Dmitry Kudryavtsev

We establish three independent results on groups acting on trees. The first implies that a compactly generated locally compact group which acts continuously on a locally finite tree with nilpotent local action and no global fixed point is…

Group Theory · Mathematics 2018-12-19 Pierre-Emmanuel Caprace , Phillip Wesolek

Motivated by the study of the large-scale geometry of topological groups, we investigate particular families of subsets of topological groups named group ideals. We compare different group ideals in the realm of locally compact groups. In…

Metric Geometry · Mathematics 2024-08-16 Dmitri Shakhmatov , Takamitsu Yamauchi , Nicolò Zava

Over each nontrivial finite group $G$, there exists a finite system of equations having no solutions in larger finite groups but having a solution in a periodic group containing $G$. We prove several similar facts about amenable, orderable,…

Group Theory · Mathematics 2025-03-04 Alexander Buturlakin , Anton Klyachko , Denis Osin

We prove that the group G=Hom(P,Z) of all homomorphisms from the Baer-Specker group P to the group Z of integer numbers endowed with the topology of pointwise convergence contains no infinite compact subsets. We deduce from this fact that…

General Topology · Mathematics 2017-05-18 Maria Vincenta Ferrer , Salvador Hernández , Dmitri Shakhmatov

We identify the class of elementary groups: the smallest class of totally disconnected locally compact second countable (t.d.l.c.s.c.) groups that contains the profinite groups and the discrete groups, is closed under group extensions of…

Group Theory · Mathematics 2015-06-12 Phillip Wesolek

We prove that over an algebraically closed field there is a representation embedding from the category of classical Kronecker-modules without the simple injective into the category of finite-dimensional modules over any…

Representation Theory · Mathematics 2023-05-30 Klaus Bongartz

We study totally disconnected locally compact second countable (t.d.l.c.s.c.) groups that contain a compact open subgroup with finite rank. We show such groups that additionally admit a pro-$\pi$ compact open subgroup for some finite set of…

Group Theory · Mathematics 2019-02-20 Phillip Wesolek

We announce various results concerning the structure of compactly generated simple locally compact groups. We introduce a local invariant, called the structure lattice, which consists of commensurability classes of compact subgroups with…

Group Theory · Mathematics 2014-05-15 Pierre-Emmanuel Caprace , Colin D. Reid , George A. Willis

We show that it is consistent with ZFC that every compact group has a non-Haar-measurable subgroup. In addition, we demonstrate a natural construction, and we conjecture that this construction always produces a non-measurable subgroup of a…

Group Theory · Mathematics 2015-03-05 W. R. Brian , M. W. Mislove

In the theory of combinatorial algebras, there is a sequence of embeddings between Kleene's second model, van Oosten's model, and Scott's graph model. We prove that none of these embeddings can be reversed. We also prove nonembedding…

Logic · Mathematics 2026-05-15 Patrick Lutz , Paul Shafer , Sebastiaan A. Terwijn

We continue the study of computable embeddings for pairs of structures, i.e. for classes containing precisely two non-isomorphic structures. Surprisingly, even for some pairs of simple linear orders, computable embeddings induce a…

Logic · Mathematics 2020-09-03 Nikolay Bazhenov , Stefan Vatev

Answering some of the main questions from [MR13], we show that whenever $\kappa$ is a cardinal satisfying $\kappa^{< \kappa} = \kappa > \omega$, then the embeddability relation between $\kappa$-sized structures is strongly invariantly…

Logic · Mathematics 2021-02-18 Filippo Calderoni , Heike Mildenberger , Luca Motto Ros

We prove that every locally compact second countable group $G$ arises as the outer automorphism group Out $M$ of a II$_1$ factor, which was so far only known for totally disconnected groups, compact groups and a few isolated examples. We…

Group Theory · Mathematics 2024-06-11 Stefaan Vaes