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Erd{\H o}s (1963) initiated extensive graph discrepancy research on 2-edge-colored graphs. Gishboliner, Krivelevich, and Michaeli (2023) launched similar research on oriented graphs. They conjectured the following extension of Dirac's…

Combinatorics · Mathematics 2026-02-12 Jiangdong Ai , Qiwen Guo , Gregory Gutin , Yongxin Lan , Qi Shao , Anders Yeo , Yacong Zhou

In this paper we give an approximate answer to a question of Nash-Williams from 1970: we show that for every \alpha > 0, every sufficiently large graph on n vertices with minimum degree at least (1/2 + \alpha)n contains at least n/8…

Combinatorics · Mathematics 2015-03-13 Demetres Christofides , Daniela Kühn , Deryk Osthus

The paper is concerned with directed versions of Posa's theorem and Chvatal's theorem on Hamilton cycles in graphs. We show that for each a>0, every digraph G of sufficiently large order n whose outdegree and indegree sequences d_1^+ \leq…

Combinatorics · Mathematics 2010-02-23 Demetres Christofides , Peter Keevash , Daniela Kühn , Deryk Osthus

Kelly, Kuehn and Osthus conjectured that for any l>3 and the smallest number k>2 that does not divide l, any large enough oriented graph G with minimum indegree and minimum outdegree at least \lfloor |V(G)|/k\rfloor +1 contains a directed…

Combinatorics · Mathematics 2012-10-24 Daniela Kühn , Deryk Osthus , Diana Piguet

Chen, Faudree, Gould, Jacobson, and Lesniak determined the minimum degree threshold for which a balanced $k$-partite graph has a Hamiltonian cycle. We give an asymptotically tight minimum degree condition for Hamiltonian cycles in arbitrary…

Combinatorics · Mathematics 2019-10-10 Louis DeBiasio , Robert A. Krueger , Dan Pritikin , Eli Thompson

An antidirected cycle in a digraph $G$ is a subdigraph whose underlying graph is a cycle, and in which no two consecutive edges form a directed path in $G$. Let $\sigma_{+-}(G)$ be the minimum value of $d^+(x)+d^-(y)$ over all pairs of…

Combinatorics · Mathematics 2026-01-01 Junqing Cai , Guanghui Wang , Yun Wang , Zhiwei Zhang

A Hamiltonian graph $G$ of order $n$ is $k$-ordered, $2\leq k \leq n$, if for every sequence $v_1, v_2, \ldots ,v_k$ of $k$ distinct vertices of $G$, there exists a Hamiltonian cycle that encounters $v_1, v_2, \ldots , v_k$ in this order.…

Combinatorics · Mathematics 2016-09-07 Gabor N. Sarkozy , Stanley Selkow

For any $k\ge 3$ and $\ell \in [k-1]$ such that $(k,\ell) \ne (3,1)$, we show that any sufficiently large $k$-graph $G$ must contain a Hamilton $\ell$-cycle provided that it has no isolated vertices and every set of $k-1$ vertices contained…

Combinatorics · Mathematics 2025-12-10 Shoham Letzter , Arjun Ranganathan

We show that a number of conditions on oriented graphs, all of which are satisfied with high probability by randomly oriented graphs, are equivalent. These equivalences are similar to those given by Chung, Graham and Wilson in the case of…

Combinatorics · Mathematics 2011-08-12 Simon Griffiths

In this paper we consider the existence of Hamilton cycles in the random graph $G=G_{n,m}^{\delta\geq 3}$. This a random graph chosen uniformly from the set of graphs with vertex set $[n]$, $m$ edges and minimum degree at least 3. Our…

Combinatorics · Mathematics 2020-06-23 Michael Anastos , Alan Frieze

Given a digraph D, the minimum semi-degree of D is the minimum of its minimum indegree and its minimum outdegree. D is k-ordered Hamiltonian if for every ordered sequence of k distinct vertices there is a directed Hamilton cycle which…

Combinatorics · Mathematics 2007-07-12 Daniela Kühn , Deryk Osthus , Andrew Young

The study of graph discrepancy problems, initiated by Erd\H{o}s in the 1960s, has received renewed attention in recent years. In general, given a $2$-edge-coloured graph $G$, one is interested in embedding a copy of a graph $H$ in $G$ with…

Combinatorics · Mathematics 2024-06-28 Andrea Freschi , Allan Lo

We study the number of edge-disjoint Hamilton cycles one can guarantee in a sufficiently large graph G on n vertices with minimum degree d = (1/2+a)n. For any constant a > 0, we give an optimal answer in the following sense: let…

Combinatorics · Mathematics 2012-11-15 Daniela Kühn , John Lapinskas , Deryk Osthus

We show that every 3-uniform hypergraph with $n$ vertices and minimum vertex degree at least $(5/9+o(1))\binom{n}2$ contains a tight Hamiltonian cycle. Known lower bound constructions show that this degree condition is asymptotically…

Combinatorics · Mathematics 2019-06-13 Christian Reiher , Vojtěch Rödl , Andrzej Ruciński , Mathias Schacht , Endre Szemerédi

A Hamilton cycle in a directed graph $G$ is a cycle that passes through every vertex of $G$. A Hamiltonian decomposition of $G$ is a partition of its edge set into disjoint Hamilton cycles. In the late $60$s Kelly conjectured that every…

Combinatorics · Mathematics 2016-10-03 Asaf Ferber , Eoin Long , Benny Sudakov

In this paper, we prove a tight minimum degree condition in general graphs for the existence of paths between two given endpoints, whose lengths form a long arithmetic progression with common difference one or two. This allows us to obtain…

Combinatorics · Mathematics 2021-01-27 Jun Gao , Qingyi Huo , Chun-Hung Liu , Jie Ma

We show that every $k$-uniform hypergraph on $n$ vertices whose minimum $(k-2)$-degree is at least $(5/9+o(1))n^2/2$ contains a Hamiltonian cycle. A construction due to Han and Zhao shows that this minimum degree condition is optimal. The…

Combinatorics · Mathematics 2022-07-08 Joanna Polcyn , Christian Reiher , Vojtěch Rödl , Bjarne Schülke

A well-known result due to Chvat\'al and Erd\H{o}s (1972) asserts that, if a graph $G$ satisfies $\kappa(G) \ge \alpha(G)$, where $\kappa(G)$ is the vertex-connectivity of $G$, then $G$ has a Hamilton cycle. We prove a similar result…

Combinatorics · Mathematics 2023-09-25 Shoham Letzter

We study minimum degree conditions under which a graph $G$ contains $k$th powers of paths and cycles of arbitrary specified lengths. We determine precise thresholds, assuming that the order of $G$ is large. This extends a result of Allen,…

Combinatorics · Mathematics 2023-06-05 Eng Keat Hng

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