English

Boolean lattice without small rainbow subposets

Combinatorics 2026-02-03 v1

Abstract

A Boolean lattice Bn=(2X,)\mathcal{B}_n=(2^X, \leq) is the power set of an nn-element ground set XX equipped with inclusion relation. For two posets P\mathcal{P} and Q\mathcal{Q}, we say that Q\mathcal{Q} contains an \emph{induced copy} of P\mathcal{P} if there exists an injection f:PQf : \mathcal{P} \to \mathcal{Q} such that f(X)f(Y)f(X) \le f(Y) if and only if XYX \le Y in P\mathcal{P}. A kk-coloring is exact if all colors are used at least once. For posets Q\mathcal{Q} and P\mathcal{P}, the \emph{Boolean Gallai-Ramsey number} GRk(Q:P)\operatorname{GR}_{k}(\mathcal{Q}:\mathcal{P}) is defined as the smallest nn such that any exact kk-coloring of the sets in Bn\mathcal{B}_n contains either a rainbow induced copy of Q\mathcal{Q} or a monochromatic induced copy of P\mathcal{P} and the \emph{Boolean rainbow Ramsey number} RR(Q:P)\operatorname{RR}(\mathcal{Q}:\mathcal{P}) is defined as the smallest nn such that any coloring of the sets in Bn\mathcal{B}_n contains either a rainbow induced copy of Q\mathcal{Q} or a monochromatic induced copy of P\mathcal{P}. In this paper, we first study the structural properties of exact kk-colorings of the sets in Boolean lattice without rainbow induced copy of small posets. As the application of these results, we give exact values and some bounds of Boolean Gallai-Ramsey numbers and Boolean rainbow Ramsey numbers, which improve a result of Chen, Cheng, Li, and Liu in 2020 and give an answer of a question proposed by Chang, Gerbner, Li, Methuku, Nagy, Patk\'{o}s, and Vizer in 2022.

Cite

@article{arxiv.2602.00680,
  title  = {Boolean lattice without small rainbow subposets},
  author = {Gyula O. H. Katona and Yaping Mao and Kenta Ozeki and Zhao Wang and Gang Yang},
  journal= {arXiv preprint arXiv:2602.00680},
  year   = {2026}
}
R2 v1 2026-07-01T09:29:22.353Z