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We establish a precise characterisation of $4$-uniform hypergraphs with minimum codegree close to $n/2$ which contain a Hamilton $2$-cycle. As an immediate corollary we identify the exact Dirac threshold for Hamilton $2$-cycles in…

Combinatorics · Mathematics 2018-04-27 Frederik Garbe , Richard Mycroft

We show that the probability that a random graph $G\sim G(n,p)$ contains no Hamilton cycle is $(1+o(1))Pr(\delta (G) < 2)$ for all values of $p = p(n)$. We also prove an analogous result for perfect matchings.

Combinatorics · Mathematics 2019-12-20 Yahav Alon , Michael Krivelevich

As one of the most fundamental and well-known NP-complete problems, the Hamilton cycle problem has been the subject of intensive research. Recent developments in the area have highlighted the crucial role played by the notions of expansion…

Combinatorics · Mathematics 2014-05-26 Daniela Kühn , Deryk Osthus

Consider the random subgraph process on a base graph $G$ with $n$ vertices: we generate a sequence $\{G_t\}_{t=0}^{|E(G)|}$ by taking a uniformly random ordering of the edges of $G$ and then adding these edges one by one to the empty graph…

Combinatorics · Mathematics 2026-03-06 Yaobin Chen , Yu Chen , Seonghyuk Im , Yiting Wang

Given a symmetric $n\times n$ matrix $P$ with $0 \le P(u, v)\le 1$, we define a random graph $G_{n, P}$ on $[n]$ by independently including any edge $\{u, v\}$ with probability $P(u, v)$. For $k\ge 1$ let $\mathcal{A}_k$ be the property of…

Combinatorics · Mathematics 2020-12-23 Tony Johansson

We investigate minimum vertex degree conditions for $3$-uniform hypergraphs which ensure the existence of loose Hamilton cycles. A loose Hamilton cycle is a spanning cycle in which only consecutive edges intersect and these intersections…

Combinatorics · Mathematics 2016-03-16 E. Buß , H. Hàn , M. Schacht

We show how to adjust a very nice coupling argument due to McDiarmid in order to prove/reprove in a novel way results concerning Hamilton cycles in various models of random graph and hypergraphs. In particular, we firstly show that for…

Combinatorics · Mathematics 2015-02-09 Asaf Ferber

We study Hamiltonicity in the union of an $n$-vertex graph $H$ with high minimum degree and a binomial random graph on the same vertex set. In particular, we consider the case when $H$ has minimum degree close to $n/2$. We determine the…

Combinatorics · Mathematics 2024-10-21 Alberto Espuny Díaz , Richarlotte Valérà Razafindravola

C. Thomassen in \cite{[11]} suggested (see also \cite{[2]}, J. C.Bermond, C. Thomassen, Cycles in Digraphs - A survey, J. Graph Theory 5 (1981) 1-43, Conjectures 1.6.7 and 1.6.8) the following conjectures : 1. Every 3-strongly connected…

Combinatorics · Mathematics 2018-01-17 S. Kh. Darbinyan

Motivated by the Gray code interpretation of Hamiltonian cycles in Cayley graphs, we investigate the existence of Hamiltonian cycles in tope graphs of hyperplane arrangements, with a focus on simplicial, reflection, and supersolvable…

Combinatorics · Mathematics 2026-04-10 Veronika Körber , Tobias Schnieders , Jan Stricker , Jasmin Walizadeh

Finding general conditions which ensure that a graph is Hamiltonian is a central topic in graph theory. An old and well known conjecture in the area states that any $d$-regular $n$-vertex graph $G$ whose second largest eigenvalue in…

Combinatorics · Mathematics 2023-03-10 Stefan Glock , David Munhá Correia , Benny Sudakov

We show that, for a natural notion of quasirandomness in $k$-uniform hypergraphs, any quasirandom $k$-uniform hypergraph on $n$ vertices with constant edge density and minimum vertex degree $\Omega(n^{k-1})$ contains a loose Hamilton cycle.…

Combinatorics · Mathematics 2015-09-15 John Lenz , Dhruv Mubayi , Richard Mycroft

A classical theorem of Ghouila-Houri from 1960 asserts that every directed graph on $n$ vertices with minimum out-degree and in-degree at least $n/2$ contains a directed Hamilton cycle. In this paper we extend this theorem to a random…

Combinatorics · Mathematics 2014-04-21 Dan Hefetz , Angelika Steger , Benny Sudakov

A subset $C$ of edges in a $k$-uniform hypergraph $H$ is a \emph{loose Hamilton cycle} if $C$ covers all the vertices of $H$ and there exists a cyclic ordering of these vertices such that the edges in $C$ are segments of that order and such…

Combinatorics · Mathematics 2016-08-04 Asaf Ferber , Kyle Luh , Daniel Montealegre , Oanh Nguyen

We prove that a random graph $G(n,p)$, with $p$ above the Hamiltonicity threshold, is typically such that for any $r$-colouring of its edges there exists a Hamilton cycle with at least $(2/(r+ 1)-o(1))n$ edges of the same colour. This…

Combinatorics · Mathematics 2021-04-22 Lior Gishboliner , Michael Krivelevich , Peleg Michaeli

Given graphs $G_1,\ldots,G_s$ all on a common vertex set and a graph $H$ with $e(H) = s$, a copy of $H$ is \emph{transversal} or \emph{rainbow} if it contains one edge from each $G_i$. We establish a stability result for transversal…

Combinatorics · Mathematics 2024-03-18 Yangyang Cheng , Katherine Staden

We give an algorithmic proof for the existence of tight Hamilton cycles in a random r-uniform hypergraph with edge probability p=n^{-1+eps} for every eps>0. This partly answers a question of Dudek and Frieze [Random Structures Algorithms],…

Combinatorics · Mathematics 2013-01-25 Peter Allen , Julia Böttcher , Yoshiharu Kohayakawa , Yury Person

We investigate the asymptotic structure of a random perfect graph $P_n$ sampled uniformly from the perfect graphs on vertex set $\{1,\ldots,n\}$. Our approach is based on the result of Pr\"omel and Steger that almost all perfect graphs are…

Combinatorics · Mathematics 2017-09-07 Colin McDiarmid , Nikola Yolov

For integers $k \geq 3$ and $r\geq 2$, we show that for every $\alpha> 0$, there exists $\varepsilon > 0$ such that the union of $k$-uniform hypergraph on $n$ vertices with minimum codegree at least $\alpha n$ and a binomial random…

Combinatorics · Mathematics 2022-11-07 Yulin Chang , Jie Han , Lubos Thoma

Let $\{G_i\}$ be the random graph process: starting with an empty graph $G_0$ with $n$ vertices, in every step $i \geq 1$ the graph $G_i$ is formed by taking an edge chosen uniformly at random among the non-existing ones and adding it to…

Combinatorics · Mathematics 2018-08-31 Rajko Nenadov , Angelika Steger , Miloš Trujić