Recurrent points and hyperarithmetic sets

Abstract

We give an example of an iteration with recursive data which stabilises exactly at the first non-recursive ordinal. We characterise the points in the final set as those attacked by recurrent points, and use that characterisation to show that recurrent points must exist for any iteration with recursive data which does not stabilise at a recursive ordinal.

Cite this paper

@inproceedings{MathiasRecurrentPA, title={Recurrent points and hyperarithmetic sets}, author={A. R. D. Mathias} }