Flexibility of the adjoint action of the group of Hamiltonian diffeomorphisms

Fuente: arXiv
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Main Authors: Buhovsky, Lev, Stokić, Maksim
Format: Preprint
Published: 2023
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author Buhovsky, Lev
Stokić, Maksim
author_facet Buhovsky, Lev
Stokić, Maksim
contents On a closed and connected symplectic manifold, the group of Hamiltonian diffeomorphisms has the structure of an infinite-dimensional Fréchet Lie group, where the Lie algebra is naturally identified with the space of smooth and zero-mean normalized functions, and the adjoint action is given by pullbacks. We show that this action is flexible: for every non-zero smooth and zero-mean normalized function $ u $, any other smooth and zero-mean function $ f $ can be written as a finite sum of elements in the orbit of $u$ under the adjoint action. Additionally, the number of elements in this sum is dominated by the uniform norm of $f$. This result can be interpreted as a (bounded) infinitesimal version of Banyaga's theorem on the simplicity of the group of Hamiltonian diffeomorphisms.
format Preprint
id arxiv_https___arxiv_org_abs_2303_04106
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Flexibility of the adjoint action of the group of Hamiltonian diffeomorphisms
Buhovsky, Lev
Stokić, Maksim
Symplectic Geometry
53D05, 22E65, 58D19
On a closed and connected symplectic manifold, the group of Hamiltonian diffeomorphisms has the structure of an infinite-dimensional Fréchet Lie group, where the Lie algebra is naturally identified with the space of smooth and zero-mean normalized functions, and the adjoint action is given by pullbacks. We show that this action is flexible: for every non-zero smooth and zero-mean normalized function $ u $, any other smooth and zero-mean function $ f $ can be written as a finite sum of elements in the orbit of $u$ under the adjoint action. Additionally, the number of elements in this sum is dominated by the uniform norm of $f$. This result can be interpreted as a (bounded) infinitesimal version of Banyaga's theorem on the simplicity of the group of Hamiltonian diffeomorphisms.
title Flexibility of the adjoint action of the group of Hamiltonian diffeomorphisms
topic Symplectic Geometry
53D05, 22E65, 58D19
url https://arxiv.org/abs/2303.04106