A new method for twist theorems

Abstract We present a new method to prove twist theorems. The method applies to $ C^{3+γ} $, measure-preserving twist maps which are not necessarily perturbations of the classical Twist, but it assumes “good behavior” for some finite orbit (which is guaranteed in particular if the map is a perturbat...
Ausführliche Beschreibung

Abstract We present a new method to prove twist theorems. The method applies to $ C^{3+γ} $, measure-preserving twist maps which are not necessarily perturbations of the classical Twist, but it assumes “good behavior” for some finite orbit (which is guaranteed in particular if the map is a perturbation or if F has a good rotation number on a boundary circle) and guarantees a set of positive measure of $ C^{2+γ−ε} $ invariant curves. Ausführliche Beschreibung