Meunier's stability conjecture for stable Kneser hypergraphs

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Let [n]={1,…,n}[n]=\{1,\ldots,n\}, and let KGr(n,k)s-stab\mathrm{KG}^r(n,k)_{s\textup{-stab}} be the induced rr-uniform Kneser hypergraph whose vertices are the ss-stable kk-subsets of [n][n], where ss-stability means s≤∣i−j∣≤n−ss\leq|i-j|\leq n-s for distinct elements i,ji,j. Meunier's conjecture. If r,s≥2r,s\geq2 and n≥max⁡{r,s}kn\geq\max\{r,s\}k, then

χ(KGr(n,k)s-stab)=⌈n−max⁡{r,s}(k−1)r−1⌉.\chi\left(\mathrm{KG}^r(n,k)_{s\textup{-stab}}\right)=\left\lceil\frac{n-\max\{r,s\}(k-1)}{r-1}\right\rceil.

This extends Ziegler's conjecture from rr-stable to ss-stable Kneser hypergraphs. The source does not specify the general resolution status; it also notes that an alternative generalization was later found incorrect.

References

Primary source

Hamid Reza Daneshpajouh, “On the Chromatic Number of Stable Kneser Hypergraphs: Verifying the Conjecture for New Families”, arXiv:2509.22026 (2025).

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