Dimensional characteristics of invariant measures for circle diffeomorphisms

Victoria Sadovskaya

Published 2008-09-02Version 1

We consider pointwise, box, and Hausdorff dimensions of invariant measures for circle diffeomorphisms. We discuss the cases of rational, Diophantine, and Liouville rotation numbers. Our main result is that for any Liouville number $\tau$ there exists a $C^\infty$ circle diffeomorphism with rotation number $\tau$ such that the pointwise and box dimensions of its unique invariant measure do not exist. Moreover, the lower pointwise and lower box dimensions can equal any value $0\le \beta \le 1$.