English

Forcing the $\Pi^1_3$-Reduction Property and a Failure of $\Pi^1_3$-Uniformization

Logic 2026-04-15 v6

Abstract

We force over the constructible universe to obtain a model of the Π31\Pi^1_3-reduction property, thus lowering the best known large cardinal strength from the existence of M1#M_1^{\#} to just ZFC. In this model the Π31\Pi^1_3-uniformization property fails, which separates these two principles for the first time.

Keywords

Cite

@article{arxiv.2009.02209,
  title  = {Forcing the $\Pi^1_3$-Reduction Property and a Failure of $\Pi^1_3$-Uniformization},
  author = {Stefan Hoffelner},
  journal= {arXiv preprint arXiv:2009.02209},
  year   = {2026}
}

Comments

30 pages. Corrected last section