English

Note on $s_0$ nonmeasurable unions

Logic 2023-01-25 v1

Abstract

In this note we consider an arbitrary families of sets of s0s_0 ideal introduced by Marczewski-Szpilrajn. We show that in any uncountable Polish space XX and under some combinatorial and set theoretical assumptions (cov(s_0)=\c for example), that for any family \cas0\ca\subseteq s_0 with \ca=X\bigcup\ca =X, we can find a some subfamily \ca\ca\ca'\subseteq\ca such that the union \ca\bigcup\ca' is not ss-measurable. We have shown a consistency of the cov(s_0)=\omega_1<\c and existence a partition of the size ω1\omega_1 \ca[s0]ω\ca\in [s_0]^{\omega} of the real line \bbr\bbr, such that there exists a subfamily \ca\ca\ca'\subseteq\ca for which \ca\bigcup\ca' is ss-nonmeasurable. We also showed that it is relatively consistent with ZFC theory that \omega_1<\c and existence of m.a.d. family \ca\ca such that \ca\bigcup\ca is ss-nonmeasurable in Cantor space 2ω2^\omega or Baire space ωω\omega^\omega. The consistency of a<cov(s0)a<cov(s_0) and cov(s0)<acov(s_0)<a is proved also.

Cite

@article{arxiv.1305.6404,
  title  = {Note on $s_0$ nonmeasurable unions},
  author = {Robert Ralowski},
  journal= {arXiv preprint arXiv:1305.6404},
  year   = {2023}
}

Comments

12 pages

R2 v1 2026-06-22T00:23:37.423Z