English

Preservation of AD via forcings

Logic 2023-04-04 v1

Abstract

We show that assuming ZF+AD++\mathsf{ZF}+\mathsf{AD}^+ + "V=L((R))V = \mathrm{L} \bigl(\wp (\mathbb{R})\bigr)", any poset which increases Θ\Theta does not preserve the truth of AD\mathsf{AD}. We also show that in ZF+AD\mathsf{ZF} + \mathsf{AD}, any non-trivial poset on R\mathbb{R} does not preserve the truth of AD\mathsf{AD}. This answers the question of Chan and Jackson. Furthermore, we show that under the assumptions ZF+AD++\mathsf{ZF}+\mathsf{AD}^+ + "V=L((R))V = \mathrm{L} \bigl(\wp (\mathbb{R})\bigr)" + "Θ is regular\Theta \text{ is regular}", there is a poset on Θ\Theta which adds a new subset of Θ\Theta while preserving the truth of AD\mathsf{AD}. This answers the question of Cunningham.

Keywords

Cite

@article{arxiv.2304.00449,
  title  = {Preservation of AD via forcings},
  author = {Daisuke Ikegami and Nam Trang},
  journal= {arXiv preprint arXiv:2304.00449},
  year   = {2023}
}