Torsion of instability zones for conservative twist maps on the annulus
Résumé
For a twist map f of the annulus preserving the Lebesgue measure, we give sufficient conditions to assure the existence of a set of positive measure of points with non-zero asymptotic torsion. In particular, we deduce that every bounded instability region for f contains a set of positive measure of points with non-zero asymptotic torsion. Moreover, for an exact symplectic twist map f , we provide a simple, geometric proof of a result by Cheng and Sun (see [CS96]) which characterizes C 0-integrability of f by the absence of conjugate points.
Domaines
Mathématiques [math]
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Florio et Calvez - 2021 - Torsion of instability zones for conservative twis.pdf (990.8 Ko)
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