English

Strong colorings over partitions

Logic 2023-06-22 v2

Abstract

A strong coloring on a cardinal κ\kappa is a function f:[κ]2κf:[\kappa]^2\to \kappa such that for every AκA\subseteq \kappa of full size κ\kappa, every color γ<κ\gamma<\kappa is attained by f[A]2f\upharpoonright[A]^2. The symbol κ[κ]κ2\kappa\nrightarrow [\kappa]^2_\kappa asserts the existence of a strong coloring on κ\kappa. We introduce the symbol κp[κ]κ2\kappa\nrightarrow_p[\kappa]^2_\kappa which asserts the existence of a coloring f:[κ]2κf:[\kappa]^2\to \kappa which is strong over a partition p:[κ]2θp:[\kappa]^2\to\theta. A coloring ff is strong over pp if for every A[κ]κA\in [\kappa]^\kappa there is i<θi<\theta so that every color γ<κ\gamma<\kappa is attained by f([A]2p1(i))f\upharpoonright ([A]^2\cap p^{-1}(i)). We prove that whenever κ[κ]κ2\kappa\nrightarrow[\kappa]^2_\kappa holds, also κp[κ]κ2\kappa\nrightarrow_p[\kappa]^2_\kappa holds for an arbitrary finite partition pp. Similarly, arbitrary finite pp-s can be added to stronger symbols which hold in any model of ZFC. If κθ=κ\kappa^\theta=\kappa, then κp[κ]κ2\kappa\nrightarrow_p[\kappa]^2_\kappa and stronger symbols, like Pr1(κ,κ,κ,χ)\mathrm{Pr}_1(\kappa,\kappa,\kappa,\chi) or Pr0(κ,κ,κ,0)\mathrm{Pr}_0(\kappa,\kappa,\kappa,\aleph_0), hold also for an arbitrary partition pp to θ\theta parts.

Cite

@article{arxiv.2002.06705,
  title  = {Strong colorings over partitions},
  author = {William Chen-Mertens and Menachem Kojman and Juris Steprans},
  journal= {arXiv preprint arXiv:2002.06705},
  year   = {2023}
}

Comments

Version accepted for publication in the Bulletin of Symbolic Logic

R2 v1 2026-06-23T13:43:22.823Z