English

Polish group actions and computability

Logic 2009-08-09 v2

Abstract

Let G be a closed subgroup of the group of all permutations of a countably infinite set. Let X be a Polish G-space with a countable basis A of clopen sets. Each x from X defines a characteristic function f on A by f(U)=1 iff x belongs to U (where U is from A). We consider computable complexity of f and some related questions.

Keywords

Cite

@article{arxiv.0903.1070,
  title  = {Polish group actions and computability},
  author = {Aleksander Ivanov and Barbara Majcher-Iwanow},
  journal= {arXiv preprint arXiv:0903.1070},
  year   = {2009}
}

Comments

AMS LaTeX file, Section 2.2 is corrected, there are some minor changes in other places

R2 v1 2026-06-21T12:18:51.428Z