Largest-component conjecture for Boolean sublattices

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 F2[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 0kn0\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

F2k(nk(nk)/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.

Sources & referencesView supporting material

Primary source

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

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