English

Ramsey numbers for partially-ordered sets

Combinatorics 2025-12-17 v1

Abstract

We say that a poset QQ contains a copy (resp.~an induced copy) of a poset PP if there is an injection f:PQf : P \to Q such that for any x,yPx,y \in P, f(x)f(y)f(x)\leq f(y) in QQ if (resp.~if and only if) xyx\leq y in PP. Let Q={Qn:n1}\mathcal{Q}=\{Q_{n} : n\geq 1\} be a family of posets such that QnQn+1Q_n\subseteq Q_{n+1} and Qn<Qn+1|Q_n|<|Q_{n+1}| for each nn. For given kk posets P1,P2,,PkP_1, P_2, \dots , P_k, the \emph{weak (resp.~strong) poset Ramsey number for tt-chains} is the smallest number nn such that for any coloring of tt-chains in QnQQ_n\in \mathcal{Q} with kk colors, say 1,2,,k1,2, \dots, k, there is a monochromatic (resp.~induced) copy of the poset PiP_i in color ii for some 1ik1\leq i\leq k. In this paper, we give several lower and upper bounds on the weak and strong poset Ramsey number for tt-chains.

Keywords

Cite

@article{arxiv.2512.14638,
  title  = {Ramsey numbers for partially-ordered sets},
  author = {Gyula O. H. Katona and Yaping Mao and Kenta Ozeki and Zhao Wang},
  journal= {arXiv preprint arXiv:2512.14638},
  year   = {2025}
}
R2 v1 2026-07-01T08:27:45.751Z