English

Antidirected trees in directed graphs

Combinatorics 2025-07-04 v2

Abstract

The Koml\'os-S\'ark\"ozy-Szemer\'edi (KSS) theorem establishes that a certain bound on the minimum degree of a graph guarantees it contains all bounded degree trees of the same order. Recently several authors put forward variants of this result, where the tree is of smaller order than the host graph, and the host graph also obeys a maximum degree condition. Also, Kathapurkar and Montgomery extended the KSS theorem to digraphs. We bring these two directions together by establishing minimum and maximum degree bounds for digraphs that ensure the containment of oriented trees of smaller order. Our result is restricted to balanced antidirected trees of bounded degree. More precisely, we show that for every γ>0\gamma > 0, cRc\in\mathbb{R}, 2\ell\geq 2 sufficiently large nn and all kγnk\geq\gamma n, the following holds for every nn-vertex digraph DD and every balanced antidirected tree TT with kk arcs whose total maximum degree is bounded by (logn)c(\log n)^c. If DD has a vertex of outdegree at least (1+γ)(1)k(1+\gamma)(\ell -1)k, a vertex of indegree at least (1+γ)(1)k(1+\gamma)(\ell -1)k and minimum semidegree δ0(D)(21+γ)k\delta^0(D)\geq\left(\frac{\ell}{2\ell -1}+\gamma\right)k, then DD contains TT.

Keywords

Cite

@article{arxiv.2501.11726,
  title  = {Antidirected trees in directed graphs},
  author = {George Kontogeorgiou and Giovanne Santos and Maya Stein},
  journal= {arXiv preprint arXiv:2501.11726},
  year   = {2025}
}

Comments

Minor improvements in exposition

R2 v1 2026-06-28T21:11:44.668Z