How can we recognize potentially ${\bf\Pi}^0_\xi$ subsets of the plane?
Logic
2009-06-01 v1 Category Theory
General Topology
Abstract
Let be a countable ordinal. We study the Borel subsets of the plane that can be made by refining the Polish topology on the real line. These sets are called potentially . We give a Hurewicz-like test to recognize potentially sets.
Keywords
Cite
@article{arxiv.0905.4875,
title = {How can we recognize potentially ${\bf\Pi}^0_\xi$ subsets of the plane?},
author = {Dominique Lecomte},
journal= {arXiv preprint arXiv:0905.4875},
year = {2009}
}