PreprintCC BY 4.0arXiv
Almost All 3-uniform Hypergraphs are Class 1
Abstract
The chromatic index χ'(H) of a hypergraph H is the smallest number of colors needed to color its edges so that no two adjacent edges share the same color. The chromatic index is trivially bounded below by the maximum degree Δ(H), and when χ'(H)= Δ(H), we say that H is Class 1. It is well known that almost every 2-graph is Class 1, and we extend this result to 3-graphs. We show for n−2/3−1/200≤ p ≤ 0.99 that the $3$-uniform binomial random hypergraph H∼ Hn,p(3) is Class 1 with high probability. We also show that this result doesn't hold for uniformities above $3$. For a broad range of p, when k ≥ 4 and k nmid n, the hypergraph H ∼ Hn,p(k) is with high probability not Class 1.
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BibTeX
@misc{chaterjee2026almost,
title = {{Almost All 3-uniform Hypergraphs are Class 1}},
author = {Arnab Chaterjee and Asaf Ferber and Marcelo Sales and Mason Shurman},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.05622},
eprint = {2611.05622},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.05622},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Almost All 3-uniform Hypergraphs are Class 1
AU - Arnab Chaterjee
AU - Asaf Ferber
AU - Marcelo Sales
AU - Mason Shurman
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2611.05622
UR - https://arxiv.org/abs/2611.05622
AB - The chromatic index χ'(H) of a hypergraph H is the smallest number of colors needed to color its edges so that no two adjacent edges share the same color. The chromatic index is trivially bounded below by the maximum degree Δ(H), and when χ'(H)= Δ(H), we say that H is Class 1. It is well known that almost every 2-graph is Class 1, and we extend this result to 3-graphs. We show for n^−2/3−1/200≤ p ≤ 0.99 that the $3$-uniform binomial random hypergraph H∼ H_n,p^(3) is Class 1 with high probability. We also show that this result doesn't hold for uniformities above $3$. For a broad range of p, when k ≥ 4 and k nmid n, the hypergraph H ∼ H_n,p^(k) is with high probability not Class 1.
ER -