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We classify finite groups that can act by automorphisms and birational automorphisms on non-trivial Severi-Brauer surfaces over fields of characteristic zero.

Algebraic Geometry · Mathematics 2020-12-18 Constantin Shramov

We consider algebraic actions of a cyclic group of order p on a K3 surface defined over an algebraically closed field of characteristic p. We classify possible loci of fixed points as well as possible quotient surfaces.

Algebraic Geometry · Mathematics 2007-05-23 I. Dolgachev , J. Keum

We study finite abelian groups acting on three-dimensional rationally connected varieties. We concentrate on the groups of K3 type, that is, abelian extensions by a cyclic group of groups that faithfully act on a K3 surface. In particular,…

Algebraic Geometry · Mathematics 2026-02-24 Konstantin Loginov , Antoine Pinardin , Zhijia Zhang

In this note, we study rigid complex manifolds that are realized as quotients of a product of curves by a free action of a finite group. They serve as higher-dimensional analogues of Beauville surfaces. Using uniformization, we outline the…

Algebraic Geometry · Mathematics 2025-04-16 Federico Fallucca , Christian Gleissner , Noah Ruhland

If $X$ is a locally compact space which admits commuting free and proper actions of locally compact groups $G$ and $H$, then the Brauer groups $\Br_H(G/X)$ and $\Br_G(X/H)$ are naturally isomorphic.

funct-an · Mathematics 2008-02-03 Alexander Kumjian , Iain Raeburn , Dana P. Williams

We derive a formula connecting the orders of the automorphism groups of a finite group and of its covering groups.

Group Theory · Mathematics 2017-07-21 Avinoam Mann

We construct k-parameter families of rational surface automorphisms for any k. These are automorphisms of surfaces X, which are constructed from iterated blowups over the projective plane. In certain cases: we are able to determine the…

Complex Variables · Mathematics 2009-02-28 Eric Bedford , Kyounghee Kim

We classify the normal CR structures on $S^3$ and their automorphism groups. Together with [3], this closes the classification of normal CR structures on contact 3-manifolds. We give a criterion to compare 2 normal CR structures, and we…

Differential Geometry · Mathematics 2007-05-23 Florin Alexandru Belgun

In this paper, the problem formulated in [8] is solved. We prove, that the group of automorphisms of the category of free associative algebras is generated by semi-inner and mirror automorphisms

Rings and Algebras · Mathematics 2007-05-23 Aivars Berzins

To any free group automorphism, we associate a real pretree with several nice properties. First, it has a rigid/non-nesting action of the free group with trivial arc stabilizers. Secondly, there is an expanding pretree-automorphism of the…

Group Theory · Mathematics 2024-05-29 Jean Pierre Mutanguha

We survey some results and questions about free actions of infinite groups on products of spheres and euclidean spaces, and give some new co-compact examples.

Geometric Topology · Mathematics 2013-01-31 Ian Hambleton , Erik K. Pedersen

An abelian group acting freely on a $\mathrm{CAT}(0)$ cube complex is free abelian.

Group Theory · Mathematics 2022-11-29 Zachary Munro

We classify abelian subgroups of the automorphism group of any compact simple Lie algebra whose centralizer has the same dimension as the dimension of the subgroup. This leads to a classification of the maximal abelian subgroups of compact…

Group Theory · Mathematics 2021-02-08 Jun Yu

We study the automorphism groups of free-by-cyclic groups and show these are finitely generated in the following cases: (i) when defining automorphism has linear growth and (ii) when the rank of the underlying free group has rank at most 3.…

Group Theory · Mathematics 2022-11-10 Naomi Andrew , Armando Martino

In this paper we survey some recent results on actions of finite groups on topological manifolds. Given an action of a finite group $G$ on a manifold $X$, these results provide information on the restriction of the action to a subgroup of…

Geometric Topology · Mathematics 2023-12-19 Ignasi Mundet i Riera

We list all finite abelian groups which act effectively on smooth cubic fourfolds.

Algebraic Geometry · Mathematics 2013-09-03 Evgeny Mayanskiy

Let $G$ be a compact Hausdorff topological group acting on a compact Hausdorff topological space $X$. Within the $C^{*}$-algebra $C(X)$ of all continuous complex-valued functions on $X$, there is the Peter-Weyl algebra $\mathcal{P}_G(X)$…

Algebraic Topology · Mathematics 2014-06-09 Paul F. Baum , Piotr M. Hajac

We classify all group topologies coarser than the topology of stabilizers of finite sets in the case of automorphism groups of countable free-homogeneous structures, Urysohn space and Urysohn sphere, among other related results.

Logic · Mathematics 2024-02-21 Zaniar Ghadernezhad , Javier de la Nuez González

We study Hamiltonian actions of compact Lie groups K on Kaehler manifolds which extend to a holomorphic action of the complexified group K^C. For a closed normal subgroup L of K we show that the Kaehlerian reduction with respect to L is a…

Symplectic Geometry · Mathematics 2011-04-13 Daniel Greb , Peter Heinzner

This article initiates a geometric study of the automorphism groups of general graph products of groups, and investigates the algebraic and geometric structure of automorphism groups of cyclic product of groups. For a cyclic product of at…

Group Theory · Mathematics 2018-03-21 Anthony Genevois , Alexandre Martin