Frankl–Kupavskii conjecture for the shifted family P(m,s,)\mathcal P(m,s,\ell)

From papers

Let n=s(m+1)n=s(m+1)-\ell and define

P(m,s,)={F[n] ⁣:F+F[1]m+1}.\mathcal P(m,s,\ell)=\{F\subseteq[n]\colon |F|+|F\cap[\ell-1]|\ge m+1\}.

For s2s\ge2, m1m\ge1, and 1s/21\le\ell\le\lceil s/2\rceil, this family is a weighted construction with matching number less than ss. Frankl–Kupavskii conjecture. Suppose that s2s\ge2, m1m\ge1, and n=s(m+1)n=s(m+1)-\ell for some \ell with 1s/21\le\ell\le\lceil s/2\rceil. Then

e(n,s)=P(m,s,).e(n,s)=|\mathcal P(m,s,\ell)|.

The source reports proofs in several ranges, including asymptotic ranges of \ell, but does not state a complete resolution.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Cheng Chi and Yan Wang, “Extremal Families for the Erdős–Kleitman Problem: The Missing Constructions”, arXiv:2607.25611 (2026).

Solutions 0

No solutions have been posted yet.