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Related papers: Continuous automorphisms of Cremona groups

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This is a survey on the automorphism groups in various classes of affine algebraic surfaces and the algebraic group actions on such surfaces. Being infinite-dimensional, these automorphism groups share some important features of algebraic…

Algebraic Geometry · Mathematics 2025-03-06 Sergei Kovalenko , Alexander Perepechko , Mikhail Zaidenberg

The group of 2-by-2 matrices with integer entries and determinant $\pm > 1$ can be identified either with the group of outer automorphisms of a rank two free group or with the group of isotopy classes of homeomorphisms of a 2-dimensional…

Group Theory · Mathematics 2007-05-23 Martin R Bridson , Karen Vogtmann

We prove that in dimensions not equal to 4, 5, or 7, the homology and homotopy groups of the classifying space of the topological group of diffeomorphisms of a disk fixing the boundary are finitely generated in each degree. The proof uses…

Algebraic Topology · Mathematics 2019-10-23 Alexander Kupers

A survey article that presents some recent algebraic and model-theoretic results on the automorphism groups of relatively free groups of infinite rank. The topics include topological aspects, generating sets, descripition of automorpisms…

Group Theory · Mathematics 2008-07-29 Vladimir Tolstykh

We study topological groups of monotonic autohomeomorphisms on a generalized ordered space $L$. We find a condition that is necessary and sufficient for the set of all monotonic autohomeomorphisms on $L$ along with the function composition…

General Topology · Mathematics 2022-12-20 Raushan Buzyakova

We study so called weakly-periodic twisted-multiplicative automorphisms of the free skew-field. In particular, we show that any automorphism of a free skew-field that is defined by a periodic automorphism of a free group is equivalent to a…

Group Theory · Mathematics 2023-04-18 Gregor Podlogar

Building on work of Farb and the second author, we prove that the group of automorphisms of the fine curve graph for a surface is isomorphic to the group of homeomorphisms of the surface. This theorem is analogous to the seminal result of…

Geometric Topology · Mathematics 2021-08-12 Adele Long , Dan Margalit , Anna Pham , Yvon Verberne , Claudia Yao

In this paper, we prove that each automorphism of a surface braid group is induced by a homeomorphism of the underlying surface, provided that this surface is a closed, connected, orientable surface of genus at least 2, and the number of…

Geometric Topology · Mathematics 2007-05-23 Elmas Irmak , Nikolai V. Ivanov , John D. McCarthy

A bounded automorphism of a field or a group with trivial approximate centre is definable. In an expansion of a field by a Pfaffian family F of additive endomorphisms such that algebraic closure in the expansion coincides with relative…

Logic · Mathematics 2024-12-09 Frank Olaf Wagner

A description of group automorphisms of all two-dimensional algebras, considered up to isomorphism, over any basic field is provided.

Rings and Algebras · Mathematics 2024-11-19 Sh. Eshmirzayev , U. Bekbaev

A detailed proof is given of a theorem describing the centraliser of a transitive permutation group, with applications to automorphism groups of objects in various categories of maps, hypermaps, dessins, polytopes and covering spaces, where…

Group Theory · Mathematics 2018-05-25 Gareth A. Jones

In this paper, we construct explicitely polynomial automorphisms of affine n-space for certain n. More precisely, we construct algebraic subgroups of the general polynomial group GA_n(k) where k is an arbitrary base ring of characteristic…

Algebraic Geometry · Mathematics 2016-10-26 Stefan Günther

A natural topology on the space of left orderings of an arbitrary semi-group is introduced. It is proved that this space is compact and that for free abelian groups it is homeomorphic to the Cantor set. An application of this result is a…

Group Theory · Mathematics 2015-05-27 Adam S. Sikora

We address the question of finding algebraic properties that are respectively equivalent, for a morphism between algebraic varieties over an algebraically closed field of characteristic zero, to be an homeomorphism for the Zariski topology…

Algebraic Geometry · Mathematics 2022-11-16 François Bernard , Goulwen Fichou , Jean-Philippe Monnier , Ronan Quarez

We study topological group theoretic properties of algebraic groups over local fields. In particular, we find conditions under which such groups have closed images under arbitrary continuous homomorphisms into arbitrary topological groups.

Group Theory · Mathematics 2023-01-04 Uri Bader , Elyasheev Leibtag

We give a method for constructing many examples of automorphisms with positive entropy on rational complex surfaces. The general idea is to begin with a quadratic Cremona transformation that fixes a reduced cubic curve and then use the…

Algebraic Geometry · Mathematics 2010-07-28 Jeffrey Diller

We show that conjugation by an automorphism of the complex numbers (as an abstract field) may change the topological fundamental group of a locally symmetric variety over C. As a consequence, we obtain a large class of algebraic varieties…

Algebraic Geometry · Mathematics 2021-01-19 James S. Milne , Junecue Suh

We show that any isomorphism between mapping class groups of orientable infinite-type surfaces is induced by a homeomorphism between the surfaces. Our argument additionally applies to automorphisms between finite-index subgroups of these…

Group Theory · Mathematics 2018-05-01 Juliette Bavard , Spencer Dowdall , Kasra Rafi

We show that plane Cremona groups over finite fields embed as dense subgroups into Neretin groups, i.e. groups of almost automorphisms of rooted trees. We also show that if the finite base field has even characteristic and contains at least…

Group Theory · Mathematics 2023-01-13 Anthony Genevois , Anne Lonjou , Christian Urech

We show that the action of Cremona transformations on the real points of quadrics exhibits the full complexity of the diffeomorphisms of the sphere, the torus, and of all non-orientable surfaces. The main result says that if X is rational,…

Algebraic Geometry · Mathematics 2009-06-08 János Kollár , Frédéric Mangolte