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Hypergraph Edge Coloring


A hypergraph edge coloring assigns colors to the hyperedges of a hypergraph so that intersecting hyperedges have different colors. The least number of colors in such a coloring is its chromatic index chi^'(H). Repeated hyperedges are allowed when H is a multihypergraph. The degree of a graph vertex is the number of incident hyperedges, counted with multiplicity, and Delta(H) is the maximum of these degrees.

Alon and Kim (1997) conjectured the following asymptotic bound. For fixed integers k>=t>=1 and every epsilon>0, a k-uniform multihypergraph in which distinct hyperedges intersect in at most t vertices satisfies

 chi^'(H)<=(t-1+1/t+epsilon)Delta(H)

when Delta(H) is sufficiently large, with its threshold depending on k, t, and epsilon. Here k-uniform means that each hyperedge has exactly k vertices. Qiao et al. (2026) report a proof of this bound. For a linear hypergraph, the intersection condition holds with t=1, giving an asymptotic coefficient 1.


See also

Edge Coloring, Hypergraph, Linear Hypergraph

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References

Alon, N. and Kim, J. H. "On the Degree, Size, and Chromatic Index of a Uniform Hypergraph." J. Combin. Th. Ser. A 77, 165-170, 1997. https://doi.org/10.1006/jcta.1996.2728.Qiao, C.; Lu, Z.; and Song, H. "The Proof of the Alon-Kim Conjecture." 10 Nov 2026. https://arxiv.org/abs/2611.13698v1.

Cite this as:

Weisstein, Eric W. "Hypergraph Edge Coloring." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/HypergraphEdgeColoring.html

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