Hegedüs's balanced Sperner family conjecture

From papers

Let [n]={1,,n}[n]=\{1,\dots,n\}. A family F2[n]\mathcal{F}\subseteq 2^{[n]} is Sperner if no two distinct members are comparable under inclusion. It is 22-balanced if there are pairwise disjoint nonempty sets I1,I2[m]I_1,I_2\subseteq[m], where F={F1,,Fm}\mathcal{F}=\{F_1,\dots,F_m\}, such that

iI1Fi=iI2Fi\bigcup_{i\in I_1}F_i=\bigcup_{i\in I_2}F_i

and

iI1Fi=iI2Fi.\bigcap_{i\in I_1}F_i=\bigcap_{i\in I_2}F_i.

Hegedüs's conjecture. If F2[n]\mathcal{F}\subseteq 2^{[n]} is a Sperner family and Fn+1|\mathcal{F}|\ge n+1, then F\mathcal{F} is 22-balanced.

The conjecture was proposed after Hegedüs proved the corresponding statement for uniform families. The supplied abstract states that the result for r=2r=2 has been proved with the sharp threshold n+1n+1, so this conjecture is solved.

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Sources & referencesView supporting material

Primary source

Chong Shangguan, Zixiang Xu and Yulin Yang, “Balanced Sperner families via the topological Tverberg theorem”, arXiv:2606.10885 (2026).

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