Largest-component conjecture for Boolean sublattices

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Let [n]={1,…,n}[n]=\{1,\ldots,n\}, let 2[n]2^{[n]} be its power set, and let GFG_{\mathcal{F}} be the graph whose vertex set is a family F⊆2[n]\mathcal{F}\subseteq 2^{[n]}, with two vertices adjacent exactly when they form a 22-chain under inclusion. Let k,nk,n be integers with 0≤k≤n0\le k\le n such that k=0k=0, k=1k=1 or kk has the same parity as nn. Largest-component conjecture. If the components of GFG_{\mathcal{F}} have order at most 2k2^k, then

∣F∣≤2k(n−k⌊(n−k)/2⌋).|\mathcal{F}|\le 2^k\binom{n-k}{\lfloor (n-k)/2\rfloor}.

This conjecture asks for the maximum size of a family whose comparability graph has no connected component larger than 2k2^k, extending the threshold perspective around Sperner's theorem. Its resolution status is not specified in the supplied text.

References

Primary source

Julian Galliano and Ross J. Kang, “Largest component in Boolean sublattices”, arXiv:2411.07985 (2025).

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