Turning Borel sets into clopen sets effectively
Volume 219 / 2012
Fundamenta Mathematicae 219 (2012), 119-143
MSC: Primary 03E15, 54H05, 03D55.
DOI: 10.4064/fm219-2-4
Abstract
We present the effective version of the theorem about turning Borel sets in Polish spaces into clopen sets while preserving the Borel structure of the underlying space. We show that under some conditions the emerging parameters can be chosen in a hyperarithmetical way and using this we obtain some uniformity results.
