English

There is a P-measure in the random model

Logic 2022-04-26 v1

Abstract

We say that a finitely additive probability measure μ\mu on ω\omega is \emph{a P-measure} if it vanishes on points and for each decreasing sequence (En)(E_n) of infinite subsets of ω\omega there is EωE\subseteq\omega such that EEnE\subseteq^* E_n for each nωn\in\omega and μ(E)=limnμ(En)\mu(E) = \lim_{n\to\infty}\mu(E_n). Thus, P-measures generalize in a natural way P-points and it is known that, similarly as in the case of P-points, their existence is independent of ZFC\mathsf{ZFC}. In this paper we show that there is a P-measure in the model obtained by adding any number of random reals to a model of CH\mathsf{CH}. As a corollary, we obtain that in the classical random model ω\omega^* contains a nowhere dense ccc closed P-set.

Keywords

Cite

@article{arxiv.2204.11694,
  title  = {There is a P-measure in the random model},
  author = {Piotr Borodulin-Nadzieja and Damian Sobota},
  journal= {arXiv preprint arXiv:2204.11694},
  year   = {2022}
}
R2 v1 2026-06-24T10:57:52.156Z