Asymptotic chromatic-number conjecture for Kneser hypergraphs of triangulations

From papers

For an integer r2r\geq 2, let KGr(Tn)\operatorname{KG}^{r}(\mathcal{T}_n) be the Kneser rr-uniform hypergraph whose vertices are the triangulations in Tn\mathcal{T}_n and whose edges are collections of rr pairwise disjoint triangulations. Let χ\chi denote its chromatic number.

Asymptotic chromatic-number conjecture. For any r2r\geq 2, there exists an integer n0(r)n_0(r) such that, for all nn0(r)n\geq n_0(r),

χ(KGr(Tn))=nrr1.\chi(\operatorname{KG}^{r}(\mathcal{T}_n))=\left\lceil\frac{n-r}{r-1}\right\rceil.

The conjecture is motivated by an upper bound obtained by extending the star construction, while the preceding equality does not hold for all n3n\geq 3. The supplied status evidence says the proposed equality was disproved, so the conjecture is refuted.

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Sources & referencesView supporting material

Primary source

Anton Molnar, Cosmin Pohoata, Michael Zheng and Daniel G. Zhu, “A Lovász-Kneser theorem for triangulations”, arXiv:2510.27689 (2025).

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