English

Cofinal families of finite VC-dimension

Logic 2025-10-03 v2 Combinatorics

Abstract

Given infinite cardinals θκ\theta\leq \kappa, we ask for the minimal VC-dimension of a cofinal family F[κ]<θ\mathcal{F}\subseteq[\kappa]^{<\theta}. We show that for θ=ω\theta=\omega and κ=n\kappa=\aleph_n it is consistent with ZFC that there exists such a family of VC-dimension n+1n+1, which is known to be the lower bound. For θ>ω\theta>\omega we answer this question completely, demonstrating a strong dichotomy between the case of singular and regular θ\theta. We furthermore answer some relative and generalized versions of the above question for singular θ\theta, and answer a related question which appears in \cite{BBNKS}.

Keywords

Cite

@article{arxiv.2509.24744,
  title  = {Cofinal families of finite VC-dimension},
  author = {Omer Ben-Neria and Itay Kaplan and George Peterzil},
  journal= {arXiv preprint arXiv:2509.24744},
  year   = {2025}
}

Comments

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