English

The typical structure of oriented graphs and digraphs with forbidden blow-up of transitive tournaments

Combinatorics 2026-04-01 v2

Abstract

We study the typical structure of oriented graphs and digraphs that do not contain a blow-up T_{r+1}^t of a transitive tournament. For any integers r >= 2, t >= 1 and any real a in (3/2,2], we prove that almost all T_{r+1}^t-free oriented graphs and almost all T_{r+1}^t-free digraphs are r-partite. This extends the results of Kuhn, Osthus, Townsend and Zhao (2017) on forbidden transitive tournaments to their blow-ups, thereby confirming a generalised form of Cherlin's conjecture. Our proof combines the hypergraph container method, a weighted analogue of the Erdos-Stone theorem for digraphs, and a stability analysis for near-extremal T_{r+1}^t-free digraphs. The core of the proof is the interplay between the directed regularity lemma and an embedding lemma, which together provide a rigorous bridge from macroscopic extremal conditions to microscopic concrete structures.

Keywords

Cite

@article{arxiv.2603.18565,
  title  = {The typical structure of oriented graphs and digraphs with forbidden blow-up of transitive tournaments},
  author = {Jianxi Liu},
  journal= {arXiv preprint arXiv:2603.18565},
  year   = {2026}
}