English

Almost continuous orbit equivalence for non-singular homeomorphisms

Dynamical Systems 2008-11-25 v1

Abstract

Let XX and YY be Polish spaces with non-atomic Borel measures μ\mu and ν\nu of full support. Suppose that TT and SS are ergodic non-singular homeomorphisms of (X,μ)(X,\mu) and (Y,ν)(Y,\nu) with continuous Radon-Nikodym derivatives. Suppose that either they are both of type III1III_1 or that they are both of type IIIλIII_\lambda, 0<λ<10<\lambda<1 and, in the IIIλIII_\lambda case, suppose in addition that both `topological asymptotic ranges' (defined in the article) are logλZ\log\lambda\cdot\Bbb Z. Then there exist invariant dense GδG_\delta-subsets XXX'\subset X and YYY'\subset Y of full measure and a non-singular homeomorphism ϕ:XY\phi: X' \to Y' which is an orbit equivalence between TXT|_{X'} and SYS|_{Y'}, that is ϕ{Tix}={Six}\phi\{T^{i}x\} = \{S^{i}x\} for all xXx \in X'. Moreover the Radon-Nikodym derivative dνϕ/dμd\nu\circ\phi/d\mu is continuous on XX' and, letting S=ϕ1SϕS' = \phi^{-1}S \phi we have Tx=Sn(x)xTx= {S'}^{n(x)}x and S=Tm(x)xS' = T^{m(x)}x where nn and mm are continuous on XX'.

Keywords

Cite

@article{arxiv.0811.3917,
  title  = {Almost continuous orbit equivalence for non-singular homeomorphisms},
  author = {Alexandre I. Danilenko and Andrés del Junco},
  journal= {arXiv preprint arXiv:0811.3917},
  year   = {2008}
}
R2 v1 2026-06-21T11:44:46.759Z