On continuous Polish group actions and equivalence relations
Logic
2015-03-17 v4
Abstract
Let X={P∈[0,1]N:(∀ν∈N)(P({ν})>0)∧ν=0∑∞P({ν})=1} be the Polish space of probability measures on N, each of which assigns positive probability to every elementary event, while for any P∈X, let ΓP={ξ∈L1(N,P):(∀ν∈N)(ξ(ν)>0)∧ν=0∑∞ξ(ν)P({ν})=1} and let ΦP:ΓP∋ξ↦ΦP(ξ)∈X be defined by the relation (ΦP(ξ))({ν})=ξ(ν)P({ν}), whenever ν∈N. If we consider the equivalence relation E={(P,Q)∈X2:(∃ξ∈ΓP)(Q=ΦP(ξ))}, the Polish space P={x∈ℓ1(R):(∀n∈N)(x(n)>0)} and the commutative Polish group G={g∈(0,∞)N:n→∞limg(n)=1}, while we set (g⋅x)(n)=g(n)x(n), whenever g∈G, x∈P and n∈N, then E is definable and it admits a strong approximation by the turbulent Polish group action of G on P.
Cite
@article{arxiv.1408.2097,
title = {On continuous Polish group actions and equivalence relations},
author = {Nikolaos E. Sofronidis},
journal= {arXiv preprint arXiv:1408.2097},
year = {2015}
}