Ergodic optimization for noncompact dynamical systems
Titel:
Ergodic optimization for noncompact dynamical systems
Auteur:
Jenkinson, O. Mauldin, R. D. Urbanski, M.
Verschenen in:
Dynamical systems
Paginering:
Jaargang 22 (2007) nr. 3 pagina's 379-388
Jaar:
2007-09
Inhoud:
The purpose of this note is to initiate the study of ergodic optimization for general topological dynamical systems T:X→ X, where the topological space X need not be compact. Given [image omitted], four possible notions of largest ergodic average are defined; for compact metrisable X these notions coincide, while for general Polish spaces X they are related by inequalities, each of which may be strict. We seek conditions on f which guarantee the existence of a normal form, in order to characterize its maximizing measures in terms of their support. For compact metrisable X it suffices to find a fixed point form. For general Polish X this is not the case, but an extra condition on f, essential compactness, is shown to imply the existence of a normal form. When T:X→ X is the full shift on a countable alphabet, essential compactness yields an easily checkable criterion for the existence of a normal form.