English

Projective measure without projective Baire

Logic 2022-10-11 v2

Abstract

We prove that it is consistent (relative to a Mahlo cardinal) that all projective sets of reals are Lebesgue measurable, but there is a Δ31\Delta^1_3 set without the Baire property. The complexity of the set which provides a counterexample to the Baire property is optimal.

Cite

@article{arxiv.1401.6808,
  title  = {Projective measure without projective Baire},
  author = {Sy Friedman and David Schrittesser},
  journal= {arXiv preprint arXiv:1401.6808},
  year   = {2022}
}
R2 v1 2026-06-22T02:55:19.346Z