Largest component in Boolean sublattices
Abstract
For a subfamily of the Boolean lattice, consider the graph on based on the pairwise inclusion relations among its members. Given a positive integer , how large can be before must contain some component of order greater than ? For , this question was answered exactly almost a century ago by Sperner: the size of a middle layer of the Boolean lattice. For , this question is trivial. We are interested in what happens between these two extremes. For with being any integer function that satisfies as , we give an asymptotically sharp answer to the above question: not much larger than the size of a middle layer. This constitutes a nontrivial generalisation of Sperner's theorem. We do so by a reduction to a Tur\'an-type problem for rainbow cycles in properly edge-coloured graphs. Among other results, we also give a sharp answer to the question, how large can be before must be connected?
Cite
@article{arxiv.2411.07985,
title = {Largest component in Boolean sublattices},
author = {Julian Galliano and Ross J. Kang},
journal= {arXiv preprint arXiv:2411.07985},
year = {2025}
}
Comments
23 pages, 2 figures; v2 includes minor corrections from review; to appear in Acta Mathematica Hungarica