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We study the automorphism group of graphons (graph limits). We prove that after an appropriate "standardization" of the graphon, the automorphism group is compact. Furthermore, we characterize the orbits of the automorphism group on…

Combinatorics · Mathematics 2021-02-17 László Lovász , Balázs Szegedy

We find a constructive bound for the word length of a generating set for the centralizer of an element of the Mapping Class Group. As a consequence, we show that it is algorithmically decidable whether two postcritically finite branched…

Geometric Topology · Mathematics 2019-02-08 Kasra Rafi , Nikita Selinger , Michael Yampolsky

We observe that, for each positive integer n > 2, each of the Artin groups of finite type A_n, B_n=C_n, and affine type \tilde A_{n-1} and \tilde C_{n-1} is a central extension of a finite index subgroup of the mapping class group of the…

Group Theory · Mathematics 2007-05-23 Ruth Charney , John Crisp

We discuss some finite homogeneous structures, addressing the question of universality of their automorphism groups. We also study the existence of so-called Kat\v{e}tov functors in finite categories of embeddings or homomorphisms.

Logic · Mathematics 2020-04-29 Wiesław Kubiś , Boriša Kuzeljević

A remarkable result of Thompson states that a finite group is soluble if and only if its two-generated subgroups are soluble. This result has been generalized in numerous ways, and it is in the core of a wide area of research in the theory…

Group Theory · Mathematics 2019-08-12 P. Hauck , L. S. Kazarin , A. Martínez-Pastor , M. D. Pérez-Ramos

We study finite p-groups G of coclass upto 4 for which the group Aut_z(G) of all central automorphisms of G is of minimal possible order. As a consequence, we obtain very short and elementary proofs of main results of Sharma and Gumber [7].

Group Theory · Mathematics 2015-03-17 Deepak Gumber , Hemant Kalra

We determine the abstract commensurator com(F) of Thompson's group F and describe it in terms of piecewise linear homeomorphisms of the real line and in terms of tree pair diagrams. We show com (F) is not finitely generated and determine…

Group Theory · Mathematics 2014-11-11 José Burillo , Sean Cleary , Claas E. Röver

Locally finite groups having the property that every non-cyclic subgroup contains its centralizer are completely classified.

Group Theory · Mathematics 2016-06-07 Costantino Delizia , Urban Jezernik , Primoz Moravec , Chiara Nicotera , Chris Parker

We complete the program begun by Brin and Squier of characterising conjugacy in Thompson's group $F$ using the standard action of $F$ as a group of piecewise linear homeomorphisms of the unit interval.

Group Theory · Mathematics 2008-04-25 Nick Gill , Ian Short

We offer a criterion for showing that the automorphism group of an ultrahomogeneous structure is topologically 2-generated and even has a cyclically dense conjugacy class. We then show how finite topological rank of the automorphism group…

Group Theory · Mathematics 2019-08-26 Itay Kaplan , Pierre Simon

We prove that for any automorphism $\alpha$ of a free group F of finite rank, one can efficiently compute a basis of the fixed point subgroup Fix(\alpha).

Group Theory · Mathematics 2014-01-16 Oleg Bogopolski , Olga Maslakova

We show how all topological full groups coming from a one-sided irreducible shift of finite type, as studied by Matui, can be re-interpreted as groups of colour-preserving tree almost automorphisms. As an application, we show that they…

Group Theory · Mathematics 2018-06-05 Waltraud Lederle

We show that if a group automorphism of a Cremona group of arbitrary rank is also a homeomorphism with respect to either the Zariski or the Euclidean topology, then it is inner up to a field automorphism of the base-field. Moreover, we show…

Algebraic Geometry · Mathematics 2019-09-25 Christian Urech , Susanna Zimmermann

In this short article, we prove that any automorphism of the R. Thompson's group $F$ has infinitely many twisted conjugacy classes. The result follows from the work of Matthew Brin, together with a standard facts on R. Thompson's group $F$,…

Group Theory · Mathematics 2007-05-23 Collin Bleak , Alexander Fel'shtyn , Daciberg L. Gonçalves

In this paper, we show that all Coleman automorphisms of a finite group with self-central minimal non-trivial characteristic subgroup are inner; therefore the normalizer property holds for these groups. Using our methods we show that the…

Group Theory · Mathematics 2017-04-21 Arne Van Antwerpen

We study asymptotic behavior of the dimensions of the homology groups of subgroups of finite index in finitely generated subgroups of pro-$p$ extension of centralizers of free pro-$p$ groups. We also prove group theoretic structure…

Group Theory · Mathematics 2013-09-11 Dessislava Kochloukova , Pavel Zalesskii

We show that generic automorphisms of stable groups are supertight in a strong sense. In particular, we obtain the existence of supertight automorphisms. We also answer a question concerning the relationship between supertight automorphisms…

Group Theory · Mathematics 2026-04-23 Piotr Kowalski , Pınar Uğurlu Kowalski

We demonstrate the existence of a family of finitely generated subgroups of Richard Thompson's group $F$ which is strictly well-ordered by the embeddability relation in type $\epsilon_0 +1$. All except the maximum element of this family…

Group Theory · Mathematics 2021-02-09 Collin Bleak , Matthew G. Brin , Justin Tatch Moore

Let $\mathbb{G}$ be a Lie group with solvable connected component and finitely-generated component group and $\alpha\in H^2(\mathbb{G},\mathbb{S}^1)$ a cohomology class. We prove that if $(\mathbb{G},\alpha)$ is of type I then the same…

Group Theory · Mathematics 2022-09-07 Alexandru Chirvasitu

We give an explicit description of the category of central extensions of a group scheme by a sheaf of Abelian groups. Based on this, we describe a framework for computing with central extensions of finite commutative group schemes, torsors…

Algebraic Geometry · Mathematics 2022-07-26 Peter Bruin
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