Outer billiards in the spaces of oriented geodesics of the three dimensional space forms

Fuente: arXiv
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Main Authors: Godoy, Yamile, Harrison, Michael, Salvai, Marcos
Format: Preprint
Published: 2021
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author Godoy, Yamile
Harrison, Michael
Salvai, Marcos
author_facet Godoy, Yamile
Harrison, Michael
Salvai, Marcos
contents Let $M_{κ}$ be the three-dimensional space form of constant curvature $κ=0,1,-1$, that is, Euclidean space $\mathbb{R}^{3}$, the sphere $S^{3} $, or hyperbolic space $H^{3}$. Let $S$ be a smooth, closed, strictly convex surface in $M_{κ}$. We define an outer billiard map $B$ on the four dimensional space $\mathcal{G}_{κ}$ of oriented complete geodesics of $M_{κ}$, for which the billiard table is the subset of $\mathcal{G}_{κ}$ consisting of all oriented geodesics not intersecting $S$. We show that $B$ is a diffeomorphism when $S$ is quadratically convex. For $κ=1,-1$, $\mathcal{G}_{κ}$ has a Kähler structure associated with the Killing form of $\operatorname{Iso}(M_{κ})$. We prove that $B$ is a symplectomorphism with respect to its fundamental form and that $B$ can be obtained as an analogue to the construction of Tabachnikov of the outer billiard in $\mathbb{R}^{2n}$ defined in terms of the standard symplectic structure. We show that $B$ does not preserve the fundamental symplectic form on $\mathcal{G}_{κ}$ associated with the cross product on $M_{κ}$, for $κ=0,1,-1$. We initiate the dynamical study of this outer billiard in the hyperbolic case by introducing and discussing a notion of holonomy for periodic points.
format Preprint
id arxiv_https___arxiv_org_abs_2110_01679
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Outer billiards in the spaces of oriented geodesics of the three dimensional space forms
Godoy, Yamile
Harrison, Michael
Salvai, Marcos
Dynamical Systems
Differential Geometry
Primary: 37C83, 53C29, 53D22. Secondary: 53A35, 53C22, 53C35
Let $M_{κ}$ be the three-dimensional space form of constant curvature $κ=0,1,-1$, that is, Euclidean space $\mathbb{R}^{3}$, the sphere $S^{3} $, or hyperbolic space $H^{3}$. Let $S$ be a smooth, closed, strictly convex surface in $M_{κ}$. We define an outer billiard map $B$ on the four dimensional space $\mathcal{G}_{κ}$ of oriented complete geodesics of $M_{κ}$, for which the billiard table is the subset of $\mathcal{G}_{κ}$ consisting of all oriented geodesics not intersecting $S$. We show that $B$ is a diffeomorphism when $S$ is quadratically convex. For $κ=1,-1$, $\mathcal{G}_{κ}$ has a Kähler structure associated with the Killing form of $\operatorname{Iso}(M_{κ})$. We prove that $B$ is a symplectomorphism with respect to its fundamental form and that $B$ can be obtained as an analogue to the construction of Tabachnikov of the outer billiard in $\mathbb{R}^{2n}$ defined in terms of the standard symplectic structure. We show that $B$ does not preserve the fundamental symplectic form on $\mathcal{G}_{κ}$ associated with the cross product on $M_{κ}$, for $κ=0,1,-1$. We initiate the dynamical study of this outer billiard in the hyperbolic case by introducing and discussing a notion of holonomy for periodic points.
title Outer billiards in the spaces of oriented geodesics of the three dimensional space forms
topic Dynamical Systems
Differential Geometry
Primary: 37C83, 53C29, 53D22. Secondary: 53A35, 53C22, 53C35
url https://arxiv.org/abs/2110.01679