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We study the 2-offer semirandom 3-uniform hypergraph model on $n$ vertices. At each step, we are presented with 2 uniformly random vertices. We choose any other vertex, thus creating a hyperedge of size 3. We show a strategy that constructs…

Combinatorics · Mathematics 2024-09-26 Michael Molloy , Pawel Pralat , Gregory B. Sorkin

An ordered graph $H$ on $n$ vertices is a graph whose vertices have been labeled bijectively with $\{1,...,n\}$. The ordered Ramsey number $r_<(H)$ is the minimum $n$ such that every two-coloring of the edges of the complete graph $K_n$…

Combinatorics · Mathematics 2019-10-31 Will Overman , Jeremy F. Alm , Kayla Coffey , Carolyn Langhoff

A central problem in extremal graph theory is to estimate, for a given graph $H$, the number of $H$-free graphs on a given set of $n$ vertices. In the case when $H$ is not bipartite, fairly precise estimates on this number are known. In…

Combinatorics · Mathematics 2017-10-13 Asaf Ferber , Gweneth Anne McKinley , Wojciech Samotij

We consider high-order connectivity in $k$-uniform hypergraphs defined as follows: Two $j$-sets are $j$-connected if there is a walk of edges between them such that two consecutive edges intersect in at least $j$ vertices. We describe the…

Combinatorics · Mathematics 2017-04-20 Oliver Cooley , Mihyun Kang , Christoph Koch

We present a variant of a universality result of R\"odl [On universality of graphs with uniformly distributed edges, Discrete Math. 59 (1986), no. 1-2, 125-134] for sparse, $3$-uniform hypergraphs contained in strongly jumbled hypergraphs.…

Combinatorics · Mathematics 2017-11-01 Yoshiharu Kohayakawa , Guilherme O. Mota , Mathias Schacht , Anusch Taraz

For a $d$-uniform random hypergraph on $n$ vertices in which hyperedges are included i.i.d.\ so that the average degree in the hypergraph is $n^{\delta+o(1)}$, the projection of such a hypergraph is a graph on the same $n$ vertices where an…

Statistics Theory · Mathematics 2026-04-03 Shuyang Gong , Zhangsong Li , Qiheng Xu

For ordered graphs $G$ and $H$, the ordered Ramsey number $r_<(G,H)$ is the smallest $n$ such that every red/blue edge coloring of the complete graph on vertices $\{1,\dots,n\}$ contains either a blue copy of $G$ or a red copy of $H$, where…

Combinatorics · Mathematics 2018-08-14 Dhruv Rohatgi

Let $G=(V,E)$ be a simple connected graph. A connected edge cover of $G$ is a subset $S\subseteq E$ such that every vertex of $G$ is incident with at least one edge in $S$ and the subgraph induced by $S$ is connected. The connected edge…

Combinatorics · Mathematics 2026-02-26 Ali Zeydi Abdian , Saeid Alikhani , Mahsa Zare

We prove a formula for the asymptotic number of edge-colored regular graphs with a prescribed set of allowed vertex-incidence structures. The formula depends on specific critical points of a polynomial encoding the vertex-incidences. As an…

Combinatorics · Mathematics 2026-01-28 Michael Borinsky , Chiara Meroni , Maximilian Wiesmann

In the last years, connection concepts such as rainbow connection and proper connection appeared in graph theory and obtained a lot of attention. In this paper, we investigate the loose edge-connection of graphs. A connected edge-coloured…

Combinatorics · Mathematics 2022-06-24 Christoph Brause , Stanislav Jendrol , Ingo Schiermeyer

We find a new structural feature of equilibrium complex random networks without multiple and self-connections. We show that if the number of connections is sufficiently high, these networks contain a core of highly interconnected vertices.…

Statistical Mechanics · Physics 2009-11-11 S. N. Dorogovtsev , J. F. F. Mendes , A. M. Povolotsky , A. N. Samukhin

We study the near-critical behavior of the sparse Erd\H{o}s-R\'enyi random graph $\mathcal{G}(n,p)$ on $n\gg1$ vertices, where the connection probability $p$ satisfies $np = 1+\theta(b_n^2/n)^{1/3}$, with $n^{3/10}\ll {b_n}\ll n^{1/2}$, and…

Probability · Mathematics 2023-12-29 Luisa Andreis , Gianmarco Bet , Maxence Phalempin

Let $Y_{3,2}$ be the $3$-uniform hypergraph with two edges intersecting in two vertices. Our main result is that any $n$-vertex 3-uniform hypergraph with at least $\binom{n}{3} - \binom{n-m+1}{3} + o(n^3)$ edges contains a collection of $m$…

Combinatorics · Mathematics 2021-10-12 Luyining Gan , Jie Han , Lin Sun , Guanghui Wang

Zarankiewicz's problem asks for the largest possible number of edges in a graph that does not contain a $K_{u,u}$ subgraph for a fixed positive integer $u$. Recently, Fox, Pach, Sheffer, Sulk and Zahl considered this problem for…

Combinatorics · Mathematics 2018-10-02 Thao Do

Given two $r$-uniform hypergraphs $F$ and $H$, we say that $H$ has an $F$-covering if every vertex in $H$ is contained in a copy of $F$. Let $c_{i}(n,F)$ be the least integer such that every $n$-vertex $r$-graph $H$ with…

Combinatorics · Mathematics 2023-08-22 Yue Ma , Xinmin Hou , Zhi Yin

Recently, we adapted exploration and martingale arguments of Nachmias and Peres, in turn based on ideas of Martin-L\"of, Karp and Aldous, to prove asymptotic normality of the number $L_1$ of vertices in the largest component $C$ of the…

Probability · Mathematics 2017-06-28 Béla Bollobás , Oliver Riordan

The theme of this paper is the derivation of analytic formulae for certain large combinatorial structures. The formulae are obtained via fluid limits of pure jump type Markov processes, established under simple conditions on the Laplace…

Probability · Mathematics 2007-05-23 R. W. R. Darling , J. R. Norris

Extensions of Erd\H{o}s-Gallai Theorem for general hypergraphs are well studied. In this work, we prove the extension of Erd\H{o}s-Gallai Theorem for linear hypergraphs. In particular, we show that the number of hyperedges in an $n$-vertex…

Combinatorics · Mathematics 2022-11-30 Ervin Győri , Nika Salia

We consider constrained variants of graph homomorphisms such as embeddings, monomorphisms, full homomorphisms, surjective homomorpshims, and locally constrained homomorphisms. We also introduce a new variation on this theme which derives…

Combinatorics · Mathematics 2014-04-23 Yangjing Long

A perfect matching in a 4-uniform hypergraph is a subset of $\lfloor\frac{n}{4}\rfloor$ disjoint edges. We prove that if $H$ is a sufficiently large 4-uniform hypergraph on $n=4k$ vertices such that every vertex belongs to more than…

Discrete Mathematics · Computer Science 2015-03-18 Imdadullah Khan