English

Fractional hypergraph coloring

Combinatorics 2025-04-18 v1

Abstract

We investigate proper (a:b)(a:b)-fractional colorings of nn-uniform hypergraphs, which generalize traditional integer colorings of graphs. Each vertex is assigned bb distinct colors from a set of aa colors, and an edge is properly colored if no single color is shared by all vertices of the edge. A hypergraph is (a:b)(a:b)-colorable if every edge is properly colored. We prove that for any 2ba2n/lnn2\leq b\leq a-2\leq n/\ln n, every nn-uniform hypergraph HH with E(H)(ab3)1/2(nlogn)1/2(ab)n1 |E(H)| \leq (ab^3)^{-1/2}\left(\frac{n}{\log n}\right)^{1/2} \left(\frac{a}{b}\right)^{n-1} is proper (a:b)(a:b)-colorable. We also address specific cases, including (a:a1)(a:a-1)-colorability.

Keywords

Cite

@article{arxiv.2504.12430,
  title  = {Fractional hypergraph coloring},
  author = {Margarita Akhmejanova and Sean Longbrake},
  journal= {arXiv preprint arXiv:2504.12430},
  year   = {2025}
}

Comments

10 pages, 1 figure