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Given $\alpha>0$ and an integer $\ell\geq5$, we prove that every sufficiently large $3$-uniform hypergraph $H$ on $n$ vertices in which every two vertices are contained in at least $\alpha n$ edges contains a copy of $C_\ell^{-}$, a tight…

Combinatorics · Mathematics 2022-11-24 Simón Piga , Marcelo Sales , Bjarne Schülke

We say that a Hamilton cycle $C=(x_1,\ldots,x_n)$ in a graph $G$ is $k$-symmetric, if the mapping $x_i\mapsto x_{i+n/k}$ for all $i=1,\ldots,n$, where indices are considered modulo $n$, is an automorphism of $G$. In other words, if we lay…

Combinatorics · Mathematics 2023-09-15 Petr Gregor , Arturo Merino , Torsten Mütze

In the standard random graph process, edges are added to an initially empty graph one by one uniformly at random. A classic result by Ajtai, Koml\'os, and Szemer\'edi, and independently by Bollob\'as, states that in the standard random…

Combinatorics · Mathematics 2026-03-24 Seonghyuk Im , Minseo Kim

Wu in 1999 conjectured that if $H$ is a subgraph of the complete graph $K_{2n+1}$ with $n$ edges, then there is a Hamiltonian cycle decomposition of $K_{2n+1}$ such that each edge of $H$ is in a separate Hamiltonian cycle. The conjecture…

Combinatorics · Mathematics 2024-03-27 Ramin Javadi , Meysam Miralaei

It has been conjectured that for any fixed $r\geq 2$ and sufficiently large $n$, there is a monochromatic Hamiltonian Berge-cycle in every $(r-1)$-coloring of the edges of $K_{n}^{r}$, the complete $r$-uniform hypergraph on $n$ vertices. In…

Combinatorics · Mathematics 2017-10-31 G. R. Omidi

For integers $k\ge 2$ and $\ell\ge 0$, a $k$-uniform hypergraph is called a loose path of length $\ell$, and denoted by $P_\ell^{(k)}$, if it consists of $\ell $ edges $e_1,\dots,e_\ell$ such that $|e_i\cap e_j|=1$ if $|i-j|=1$ and $e_i\cap…

Combinatorics · Mathematics 2023-06-22 Andrzej Dudek , Andrzej Ruciński

For a graph $G$ the random $n$-lift of $G$ is obtained by replacing each of its vertices by a set of $n$ vertices, and joining a pair of sets by a random matching whenever the corresponding vertices of $G$ are adjacent. We show that…

Combinatorics · Mathematics 2014-01-07 Tomasz Łuczak , Łukasz Witkowski , Marcin Witkowski

An {\em ordered $r$-graph} is an $r$-uniform hypergraph whose vertex set is linearly ordered. Given $2\leq k\leq r$, an ordered $r$-graph $H$ is {\em interval} $k$-{\em partite} if there exist at least $k$ disjoint intervals in the ordering…

Combinatorics · Mathematics 2020-04-13 Zoltán F\" uredi , Tao Jiang , Alexandr Kostochka , Dhruv Mubayi , Jacques Verstraëte

A packing of a graph G with Hamilton cycles is a set of edge-disjoint Hamilton cycles in G. Such packings have been studied intensively and recent results imply that a largest packing of Hamilton cycles in G_n,p a.a.s. has size \lfloor…

Combinatorics · Mathematics 2013-07-25 Dan Hefetz , Daniela Kühn , John Lapinskas , Deryk Osthus

For an integer $r\geqslant 3$, a hypergraph on vertex set $[n]$ is $r$-uniform if each edge is a set of $r$ vertices, and is said to be linear if every two distinct edges share at most one vertex. Given a family $\mathcal{H}$ of linear…

Combinatorics · Mathematics 2026-01-28 Fang Tian , Yiting Yang , Xiying Yuan

Let $X_1,X_2,\ldots,X_n$ be chosen independently and uniformly at random from the unit $d$-dimensional cube $[0,1]^d$. Let $r$ be given and let $\cal X=\{X_1,X_2,\ldots,X_n\}$. The random geometric graph $G=G_{\cal X,r}$ has vertex set…

Combinatorics · Mathematics 2023-09-14 Alan Frieze , Xavier Pérez-Giménez

We present a tight extremal threshold for the existence of Hamilton cycles in graphs with large minimum degree and without a large ``bipartite hole`` (two disjoint sets of vertices with no edges between them). This result extends Dirac's…

Combinatorics · Mathematics 2016-04-20 Colin McDiarmid , Nikola Yolov

We introduce a new setting of algorithmic problems in random graphs, studying the minimum number of queries one needs to ask about the adjacency between pairs of vertices of ${\mathcal G}(n,p)$ in order to typically find a subgraph…

Combinatorics · Mathematics 2016-08-05 Asaf Ferber , Michael Krivelevich , Benny Sudakov , Pedro Vieira

Sidorenko's conjecture states that, for all bipartite graphs $H$, quasirandom graphs contain asymptotically the minimum number of copies of $H$ taken over all graphs with the same order and edge density. While still open for graphs, the…

Combinatorics · Mathematics 2024-05-28 David Conlon , Joonkyung Lee , Alexander Sidorenko

A tuple $(G_1,\dots,G_n)$ of graphs on the same vertex set of size $n$ is said to be Hamilton-universal if for every map $\chi: [n]\to[n]$ there exists a Hamilton cycle whose $i$-th edge comes from $G_{\chi(i)}$. Bowtell, Morris, Pehova and…

Combinatorics · Mathematics 2026-02-26 Micha Christoph , Anders Martinsson , Aleksa Milojević

We show that provided $\log^{50} n/n \leq p \leq 1 - n^{-1/4}\log^9 n$ we can with high probability find a collection of $\lfloor \delta(G)/2 \rfloor$ edge-disjoint Hamilton cycles in $G \sim G_{n, p}$, plus an additional edge-disjoint…

Combinatorics · Mathematics 2013-05-09 Fiachra Knox , Daniela Kühn , Deryk Osthus

We prove that there exists a positive constant \epsilon such that if \log n / n \le p \le n^{-1+\epsilon}, then asymptotically almost surely the random graph G ~ G(n,p) contains a collection of \lfloor \delta(G)/2 \rfloor edge-disjoint…

Combinatorics · Mathematics 2011-09-27 Michael Krivelevich , Wojciech Samotij

We show that if pn >> log n, the binomial random graph G_{n,p} has an approximate Hamilton decomposition. More precisely, we show that in this range G_{n,p} contains a set of edge-disjoint Hamilton cycles covering almost all of its edges.…

Combinatorics · Mathematics 2013-07-05 Fiachra Knox , Daniela Kühn , Deryk Osthus

We consider Hamilton cycles in the random digraph $D_{n,m}$ where the orientation of edges follows a pattern other than the trivial orientation in which the edges are oriented in the same direction as we traverse the cycle. We show that if…

Combinatorics · Mathematics 2020-10-19 Alan Frieze , Xavier Perez-Gimenez , Pawel Pralat

We study Hamilton cycles and perfect matchings in a uniform attachment graph. In this random graph, vertices are added sequentially, and when a vertex $t$ is created, it makes $k$ independent and uniform choices from $\{1,\dots,t-1\}$ and…

Combinatorics · Mathematics 2019-08-13 Huseyin Acan