English

On the closed Ramsey numbers $R^{cl}(\omega+n,3)$

Logic 2022-04-20 v1 Combinatorics

Abstract

In this paper, we contribute to the study of topological partition relations for pairs of countable ordinals and prove that, for all integers n3n \geq 3, \begin{align*} R^{cl}(\omega+n,3) &\geq \omega^2 \cdot n + \omega \cdot (R(n,3)-n)+n\\ R^{cl}(\omega+n,3) &\leq \omega^2 \cdot n + \omega \cdot (R(2n-3,3)+1)+1 \end{align*} where Rcl(,)R^{cl}(\cdot,\cdot) and R(,)R(\cdot,\cdot) denote the closed Ramsey numbers and the classical Ramsey numbers respectively. We also establish the following asymptotically weaker upper bound Rcl(ω+n,3)ω2n+ω(n24)+1 R^{cl}(\omega+n,3) \leq \omega^2 \cdot n + \omega \cdot (n^2-4)+1 eliminating the use of Ramsey numbers. These results improve the previously known upper and lower bounds.

Keywords

Cite

@article{arxiv.2005.09519,
  title  = {On the closed Ramsey numbers $R^{cl}(\omega+n,3)$},
  author = {Burak Kaya and Irmak Saglam},
  journal= {arXiv preprint arXiv:2005.09519},
  year   = {2022}
}