English

A note on embedding hypertrees

Combinatorics 2009-05-26 v3

Abstract

A classical result from graph theory is that every graph with chromatic number \chi > t contains a subgraph with all degrees at least t, and therefore contains a copy of every t-edge tree. Bohman, Frieze, and Mubayi recently posed this problem for r-uniform hypergraphs. An r-tree is an r-uniform hypergraph with no pair of edges intersecting in more than one vertex, and no sequence of distinct vertices and edges (v_1, e_1, ..., v_k, e_k) with all e_i \ni {v_i, v_{i+1}}, where we take v_{k+1} to be v_1. Bohman, Frieze, and Mubayi proved that \chi > 2rt is sufficient to embed every r-tree with t edges, and asked whether the dependence on r was necessary. In this note, we completely solve their problem, proving the tight result that \chi > t is sufficient to embed any r-tree with t edges.

Keywords

Cite

@article{arxiv.0901.2988,
  title  = {A note on embedding hypertrees},
  author = {Po-Shen Loh},
  journal= {arXiv preprint arXiv:0901.2988},
  year   = {2009}
}

Comments

4 pages; minor revisions, with updated references

R2 v1 2026-06-21T12:02:42.925Z