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We study large groups of birational transformations Bir(X), where X is a variety of dimension at least 3, defined over C or a subfield of C. Two prominent cases are when X is the projective space, in which case Bir(X) is the Cremona group…

Algebraic Geometry · Mathematics 2021-10-08 Jérémy Blanc , Stéphane Lamy , Susanna Zimmermann

We initiate the study of the ''algebraic growth'' of groups of automorphisms and birational transformations of algebraic varieties. Our main result concerns $\text{Bir}(\mathbb{P}^2)$, the Cremona group in $2$ variables. This group is the…

Algebraic Geometry · Mathematics 2025-03-07 Alberto Calabri , Serge Cantat , Alex Massarenti , François Maucourant , Massimiliano Mella

Let $X$ be a projective variety of dimension $r$ over an algebraically closed field. It is proven that two birational embeddings of $X$ in $\P^n$, with $n\geq r+2$ are equivalent up to Cremona transformations of $\P^n$.

Algebraic Geometry · Mathematics 2014-02-26 Massimiliano Mella , Elena Polastri

This paper contains a new proof of the classification of elements of prime order in the Cremona group Bir(P^2), up to conjugation. In addition, we give explicit geometric constructions of these Cremona transformations, and provide a…

Algebraic Geometry · Mathematics 2007-05-23 Tommaso de Fernex

The Cremona group $\mathrm{Bir}(\mathbb{P}^2_\mathbb{C})$ is the group of birational self-maps of $\mathbb{P}^2_\mathbb{C}$. Using the action of $\mathrm{Bir}(\mathbb{P}^2_\mathbb{C})$ on the Picard-Manin space of $\mathbb{P}^2_\mathbb{C}$…

Algebraic Geometry · Mathematics 2016-08-02 Julie Déserti

We recall some properties, unfortunately not all, of the Cremona group. We first begin by presenting a nice proof of the amalgamated product structure of the well-known subgroup of the Cremona group made up of the polynomial automorphisms…

Algebraic Geometry · Mathematics 2016-02-17 Julie Déserti

We describe the nilpotent subgroups of the group Bir(P^2(C)) of birational transformations of the complex projective plane. Let N be a nilpotent subgroup of class k>1; then either each element of N has finite order, or N is virtually…

Group Theory · Mathematics 2007-05-23 Julie Deserti

Motivated by the study of the Kahan--Hirota--Kimura discretisation of the Euler top, we characterise the growth and integrability properties of a collection of elements in the Cremona group of a complex projective 3-space using techniques…

Algebraic Geometry · Mathematics 2023-06-06 Michele Graffeo , Giorgio Gubbiotti

Let $\mathbf{K}$ be an algebraically closed field. The Cremona group $\operatorname{Cr}_2(\mathbf{K})$ is the group of birational transformations of the projective plane $\mathbb{P}^2_{\mathbf{K}}$. We carry out an overall study of…

Algebraic Geometry · Mathematics 2021-01-21 ShengYuan Zhao

For an algebraic variety $X$ we study the behavior of algebraic morphisms from an algebraic variety to the group $\bir(X)$ of birational maps of $X$ and obtain, as application, some insight about the relationship between the so-called…

Algebraic Geometry · Mathematics 2013-09-17 Ivan Pan , Alvaro Rittatore

The Cremona group of birational transformations of $\mathbb{P}^2_\mathbb{C}$ acts on the space $\mathbb{F}(2)$ of holomorphic foliations on the complex projective plane. Since this action is not compatible with the natural graduation of…

Dynamical Systems · Mathematics 2015-12-29 Dominique Cerveau , Julie Déserti

We study embeddings of symmetric groups to the space Cremona group.

Algebraic Geometry · Mathematics 2022-03-24 Yuri Prokhorov

This article studies the group generated by automorphisms of the projective space of dimension $n$ and by the standard birational involution of degree $n$. Every element of this group only contracts rational hypersurfaces, but in odd…

Algebraic Geometry · Mathematics 2019-02-14 Jérémy Blanc , Isac Hedén

Let M be a connected generic real-analytic CR-submanifold of a finite-dimensional complex vector space E. Suppose that for every point a in M the Lie algebra hol(M,a) of germs of all infinitesimal real-analytic CR-automorphisms of M at a is…

Complex Variables · Mathematics 2009-06-18 A. Isaev. , W. Kaup

A Cremona transformation is a birational self-map of the projective space $ \mathbb{P}^{n} $. Cremona transformations of $ \mathbb{P}^{n} $ form a group and this group has a rational action on subvarieties of $ \mathbb{P}^{n} $ and hence on…

Algebraic Geometry · Mathematics 2019-06-05 Elena Angelini , Massimiliano Mella

We study linearizability properties of finite subgroups of the Cremona group ${\mathrm{Cr}}_n(k)$ in the case where $k$ is a global field, with the focus on the local-global principle. For every global field $k$ of characteristic different…

Algebraic Geometry · Mathematics 2025-08-12 Boris Kunyavskii

Using a filtration on the Grothendieck ring of triangulated categories, we define the categorical dimension of a birational map between smooth projective varieties. We show that birational automorphisms of bounded categorical dimension form…

Algebraic Geometry · Mathematics 2020-10-06 Marcello Bernardara

Let k be an algebraically closed field. We show that the Cremona group of all birational transformations of the projective plane P^2 over k is not a simple group. The strategy makes use of hyperbolic geometry, geometric group theory, and…

Algebraic Geometry · Mathematics 2018-04-24 Serge Cantat , Stéphane Lamy

We prove that any two algebraic embeddings of $\mathbb{C}$ into $\textrm{SL}_n(\mathbb{C})$ are the same up to an algebraic automorphism of $\textrm{SL}_n(\mathbb{C})$, provided that $n$ is at least $3$. Moreover, we prove that two…

Algebraic Geometry · Mathematics 2016-11-24 Immanuel Stampfli

We present some (unfortunately not all) known properties on the Cremona group; when it's possible we mentioned links with the most known group of polynomial automorphisms of the affine plane. The mentioned properties are essentially…

Algebraic Geometry · Mathematics 2009-09-22 Julie Déserti
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