Maximizing points and coboundaries for an irrational rotation on the Circle

Julien Brémont (1)

1 LAMA - Laboratoire d'Analyse et de Mathématiques Appliquées

Consider an irrational rotation of the unit circle and a real continuous function. A point is declared \maximizing" if the growth of the ergodic sums at this point is maximal up to an additive constant. In case of two-sided ergodic sums the existence of a maximizing point for a continuous function implies that it is the coboundary of a continuous function. In contrast, we build for the \usual" one-sided ergodic sums examples in Holder or smooth classes indicating that all kinds of behaviour of the function with respect to the dynamical system are possible. We also show that generic continuous functions are without maximizing points, not only for rotations, but for the transformation 2x mod 1 as well. For this latter transformation it is known that any Holder continuous function has a maximizing point.

Domaines: Systèmes dynamiques [math.DS]

Julien Brémont. Maximizing points and coboundaries for an irrational rotation on the Circle. ETDS, 2013, 33 (1), pp.24-48. ⟨hal-00794137⟩