English

Packing the largest trees in the tree packing conjecture

Combinatorics 2026-04-13 v2

Abstract

The famous tree packing conjecture of Gy\'arf\'as from 1976 says that any sequence of trees T1,,TnT_1,\ldots,T_n such that Ti=i|T_i|=i for each i[n]i\in [n] packs into the complete nn-vertex graph KnK_n. Packing even just the largest trees in such a sequence has proven difficult, with Bollob\'as drawing attention to this in 1995 by conjecturing that, for each kk, if nn is sufficiently large then the largest kk trees in any such sequence can be packed into KnK_n. This has only been shown for k5k\leq 5, by \.{Z}ak, despite many partial results and much related work on the full tree packing conjecture. We prove Bollob\'as's conjecture, by showing that, moreover, a linear number of the largest trees can be packed in the tree packing conjecture.

Keywords

Cite

@article{arxiv.2403.10515,
  title  = {Packing the largest trees in the tree packing conjecture},
  author = {Barnabás Janzer and Richard Montgomery},
  journal= {arXiv preprint arXiv:2403.10515},
  year   = {2026}
}

Comments

34 pages, 5 figures. Version accepted for publication

R2 v1 2026-06-28T15:22:07.862Z