Herman's Theory Revisited (Extension)

Abstract

We prove that a $C^{3+\beta }$-smooth orientation-preserving circle diffeomorphism with rotation number in Diophantine class $D_{\delta }$, $0<\beta <\delta <1$, is $C^{2+\beta -\delta }$-smoothly conjugate to a rigid rotation.

12 pages, this paper is a logical continuation of its first reference; aknowledgement added