Non-meager free sets and independent families
Abstract
Our main result is that, given a collection $\mathcal{R}$ of meager relations on a Polish space $X$ such that $|\mathcal{R}|\leq\omega$, there exists a dense Baire subspace $F$ of $X$ (equivalently, a nowhere meager subset $F$ of $X$) such that $F$ is $R$-free for every $R\in\mathcal{R}$. This generalizes a recent result of Banakh and Zdomskyy. As an application, we show that there exists a non-meager independent family on $\omega$, and define the corresponding cardinal invariant. Furthermore, assuming Martin's Axiom for countable posets, our result can be strengthened by substituting "$|\mathcal{R}|\leq\omega$" with "$|\mathcal{R}|<\mathfrak{c}$" and "Baire" with "completely Baire".
- Publication:
-
arXiv e-prints
- Pub Date:
- August 2015
- DOI:
- 10.48550/arXiv.1508.00124
- arXiv:
- arXiv:1508.00124
- Bibcode:
- 2015arXiv150800124M
- Keywords:
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- Mathematics - General Topology;
- Mathematics - Logic;
- 54E50;
- 54E52;
- 03E05;
- 03E50
- E-Print:
- 13 pages