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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…

Combinatorics · Mathematics 2026-04-01 Jianxi Liu

For integers \(r\ge 2\), \(t\ge 1\) and a real number \(a\in(3/2,2]\), 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. We prove that almost every…

Combinatorics · Mathematics 2026-05-26 Meili Liang , Yue Guan , Ruiling Zheng , Jianxi Liu

In a seminal work, K\"uhn, Osthus, Townsend, and Zhao used the hypergraph container method to determine the typical structure of oriented graphs and digraphs avoiding a fixed tournament or cycle. Their main tool, a container theorem for…

Combinatorics · Mathematics 2026-05-20 Meili Liang , Yue Guan , Ruiling Zheng , Jianxi Liu

It is an intriguing question to see what kind of information on the structure of an oriented graph $D$ one can obtain if $D$ does not contain a fixed oriented graph $H$ as a subgraph. The related question in the unoriented case has been an…

Combinatorics · Mathematics 2010-11-22 Omid Amini , Simon Griffiths , Florian Huc

In an earlier paper the first two authors have shown that self-complementary graphs can always be oriented in such a way that the union of the oriented version and its isomorphically oriented complement gives a transitive tournament. We…

Combinatorics · Mathematics 2018-06-05 Attila Sali , Gábor Simonyi , Gábor Tardos

For a fixed finite set of finite tournaments ${\mathcal F}$, the ${\mathcal F}$-free orientation problem asks whether a given finite undirected graph $G$ has an $\mathcal F$-free orientation, i.e., whether the edges of $G$ can be oriented…

Combinatorics · Mathematics 2024-09-02 Manuel Bodirsky , Santiago Guzmán-Pro

In this work, we establish an analogue result of the Erd\"os-Stone theorem of weighted digraphs using Regularity Lemma of digraphs. We give a stability result of oriented graphs and digraphs with forbidden blow-up transitive triangle and…

Combinatorics · Mathematics 2017-03-10 Jianxi Liu

Thomason [$\textit{Trans. Amer. Math. Soc.}$ 296.1 (1986)] proved that every sufficiently large tournament contains Hamilton paths and cycles with all possible orientations, except possibly the consistently oriented Hamilton cycle. This…

Combinatorics · Mathematics 2024-07-22 Debsoumya Chakraborti , Jaehoon Kim , Hyunwoo Lee , Jaehyeon Seo

The orientation completion problem for a class of oriented graphs asks whether a given partially oriented graph can be completed to an oriented graph in the class by orienting the unoriented edges of the partially oriented graph.…

Combinatorics · Mathematics 2022-11-07 Kevin Hsu , Jing Huang

A classical Tur\'an problem asks for the maximum possible number of edges in a graph of a given order that does not contain a particular graph $H$ as a subgraph. It is well-known that the chromatic number of $H$ is the graph parameter which…

We prove a strong dichotomy result for countably-infinite oriented graphs; that is, we prove that for all countably-infinite oriented graphs $G$, either (i) there is a countably-infinite tournament $K$ such that $G\not\subseteq K$, or (ii)…

Combinatorics · Mathematics 2024-05-02 Alistair Benford , Louis DeBiasio , Paul Larson

The method of hypergraph containers, introduced recently by Balogh, Morris, and Samotij, and independently by Saxton and Thomason, has proved to be an extremely useful tool in the study of various monotone graph properties. In particular, a…

Combinatorics · Mathematics 2018-06-12 Robert Morris , Wojciech Samotij , David Saxton

In this survey we describe a recently-developed technique for bounding the number (and controlling the typical structure) of finite objects with forbidden substructures. This technique exploits a subtle clustering phenomenon exhibited by…

Combinatorics · Mathematics 2018-01-16 József Balogh , Robert Morris , Wojciech Samotij

In this thesis we consider ordered graphs (that is, graphs with a fixed linear ordering on their vertices). We summarize and further investigations on the number of edges an ordered graph may have while avoiding a fixed forbidden ordered…

Discrete Mathematics · Computer Science 2009-07-16 Craig Weidert

In 1974, Erd\H{o}s posed the following problem. Given an oriented graph $H$, determine or estimate the maximum possible number of $H$-free orientations of an $n$-vertex graph. When $H$ is a tournament, the answer was determined precisely…

Combinatorics · Mathematics 2021-06-17 Matija Bucić , Oliver Janzer , Benny Sudakov

We study variants of Sidorenko's conjecture in tournaments, where new phenomena arise that do not have clear analogues in the setting of undirected graphs. We first consider oriented graphs that are systematically under-represented in…

Combinatorics · Mathematics 2024-02-14 Jacob Fox , Zoe Himwich , Nitya Mani , Yunkun Zhou

We show that digraphs with no transitive tournament on $3$ vertices and in which every induced directed cycle has length $3$ can have arbitrarily large dichromatic number. This answers to the negative a question of Carbonero, Hompe, Moore,…

Combinatorics · Mathematics 2022-02-03 Pierre Aboulker , Nicolas Bousquet , Rémi de Verclos

Directed graphs occur throughout statistical modeling of networks, and exchangeability is a natural assumption when the ordering of vertices does not matter. There is a deep structural theory for exchangeable undirected graphs, which…

Statistics Theory · Mathematics 2016-12-19 Diana Cai , Nathanael Ackerman , Cameron Freer

In 1974, Erd\H{o}s asked the following question: given a graph $G$ and a directed graph $\vec{H}$, how many ways are there to orient the edges of $G$ such that it does not contain $\vec{H}$ as a subgraph? We denote this value by $D(G,…

Combinatorics · Mathematics 2025-04-04 Hannah Sheats

For a set F of finite tournaments, the F-free orientation problem is the problem of deciding if a given finite undirected graph can be oriented in such a way that the resulting oriented graph does not contain any member of F. Using the…

Combinatorics · Mathematics 2025-09-03 Roman Feller , Michael Pinsker
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