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In previous work, the first author established a natural bijection between minimal subshifts and maximal regular J-classes of free profinite semigroups. In this paper, the Sch\"utzenberger groups of such J-classes are investigated, in…

Group Theory · Mathematics 2013-03-01 Jorge Almeida , Alfredo Costa

We give a description of finitely generated prosoluble subgroups of the profinite completion of $3$-manifold groups and virtually compact special groups.

Geometric Topology · Mathematics 2025-12-22 Lucas C. Lopes , Pavel A. Zalesskii

This paper establishes strong profinite rigidity results for K\"ahler groups, showing that certain groups are determined within the class of residually finite K\"ahler groups by their profinite completion. Examples include products of…

Geometric Topology · Mathematics 2025-01-24 Sam Hughes , Claudio Llosa Isenrich , Pierre Py , Matthew Stover , Stefano Vidussi

Broadly speaking, a finiteness property of groups is any generalisation of the property of having finite order. A large part of infinite group theory is concerned with finiteness properties and the relationships between them. Profinite…

Group Theory · Mathematics 2010-02-16 Colin Reid

We define the profinite completion of a C*-algebra, which is a pro-C*-algebra, as well as the pro-C*-algebra of a profinite group. We show that the continuous representations of the pro-C*-algebra of a profinite group correspond to the…

Operator Algebras · Mathematics 2012-04-23 Rachid El Harti , N. Christopher Phillips , Paulo R. Pinto

The subgroup lattice of a group is a great source of information about the structure of the group itself. The aim of this paper is to use a similar tool for studying profinite groups. In more detail, we study the lattices of closed or open…

Group Theory · Mathematics 2024-01-12 Francesco de Giovanni , Iker de las Heras , Marco Trombetti

The article deals with profinite groups in which the centralizers are abelian (CA-groups), that is, with profinite commutativity-transitive groups. It is shown that such groups are virtually pronilpotent. More precisely, let G be a…

Group Theory · Mathematics 2018-07-09 Pavel Shumyatsky , Pavel Zalesskii , Theo Zapata

We define a filtration of the smooth concordance group based on the genus of representative knots. We use the Heegaard Floer epsilon and Upsilon invariants to prove the quotient groups with respect to this filtration are infinitely…

Geometric Topology · Mathematics 2016-11-30 Shida Wang

A group $G$ is said to be a $C$-group if every subgroup $H$ has a permutable complement, i.e. if there exists a subgroup $K$ of $G$ such that $G=HK$ and $H \cap K=1$. In this paper, we study the profinite counterpart of this concept. We say…

Group Theory · Mathematics 2025-07-29 Gustavo A. Fernández-Alcober , Giulia Sabatino

We construct the first example of a finitely-presented, residually-finite group that contains an infinite sequence of non-isomorphic finitely-presented subgroups such that each of the inclusion maps induces an isomorphism of profinite…

Group Theory · Mathematics 2015-01-08 Martin R. Bridson

Let $p$ be a prime. We resolve a question posed by Min\'a\v{c}-Rogelstad-T\^an. We relate the Zassenhaus and the lower central series of pro-$p$ groups under a torsion-freeness condition. We also study graph products of (pro-$p$) groups…

Group Theory · Mathematics 2026-01-30 Oussama Hamza

We prove that certain Fuchsian triangle groups are profinitely rigid in the absolute sense, i.e. each is distinguished from all other finitely generated, residually finite groups by its set of finite quotients. We also develop a method…

Group Theory · Mathematics 2021-10-04 M. R. Bridson , D. B. McReynolds , A. W. Reid , R. Spitler

We say that a group $G$ is of \textit{profinite type} if it can be realized as a Galois group of some field extension. Using Krull's theory, this is equivalent to the ability of $G$ to be equipped with a profinite topology. We also say that…

Group Theory · Mathematics 2024-03-14 Tamar Bar-On , Nikolay Nikolov

The article deals with profinite groups in which the centralizers are pronilpotent (CN-groups). It is shown that such groups are virtually pronilpotent. More precisely, let G be a profinite CN-group, and let F be the maximal normal…

Group Theory · Mathematics 2018-09-13 Pavel Shumyatsky

We describe free prosoluble subgroups of a free product of profinite groups by strengthening the theorem of Frorian Pop and answering two questions of K. Ersoy and W. Herfort. Relatively projective prosoluble groups are also described.

Group Theory · Mathematics 2024-11-20 Pavel Zalesskii

We develop the theory of Mackey profunctors, a version of Mackey functors for profinite groups.

K-Theory and Homology · Mathematics 2022-09-20 D. Kaledin

Hyperelliptic mapping class groups are defined either as the centralizers of hyperelliptic involutions inside mapping class groups of oriented surfaces of finite type or as the inverse images of these centralizers by the natural…

Geometric Topology · Mathematics 2024-02-12 Marco Boggi

We prove that if a Cartesian product of alternating groups is topologically finitely generated, then it is the profinite completion of a finitely generated residually finite group. The same holds for Cartesian producs of other simple groups…

Group Theory · Mathematics 2007-05-23 Martin Kassabov , Nikolay Nikolov

For a formation $\mathfrak{F}$ of finite groups, tight connections are established between the pro-$\mathfrak{F}$-topology of a finitely generated free group $F$ and the geometry of the Cayley graph $\Gamma(\hat{F_{\mathfrak{F}}})$ of the…

Group Theory · Mathematics 2016-01-22 K. Auinger

The set of all closed subgroups of a profinite carries a natural profinite topology. This space of subgroups can be classified up to homeomorphism in many cases, and tight bounds placed on its complexity as expressed by its scattered…

Group Theory · Mathematics 2008-09-30 Paul Gartside , Michael Smith