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Related papers: A precise threshold for quasi-Ramsey numbers

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The anti-Ramsey numbers are a fundamental notion in graph theory, introduced in 1978, by Erd\" os, Simonovits and S\' os. For given graphs $G$ and $H$ the \emph{anti-Ramsey number} $\textrm{ar}(G,H)$ is defined to be the maximum number $k$…

Computational Complexity · Computer Science 2020-07-06 Saeed Akhoondian Amiri , Alexandru Popa , Mohammad Roghani , Golnoosh Shahkarami , Reza Soltani , Hossein Vahidi

We prove that $s_r(K_k) = O(k^5 r^{5/2})$, where $s_r(K_k)$ is the Ramsey parameter introduced by Burr, Erd\H{o}s and Lov\'{a}sz in 1976, which is defined as the smallest minimum degree of a graph $G$ such that any $r$-colouring of the…

Combinatorics · Mathematics 2022-10-25 John Bamberg , Anurag Bishnoi , Thomas Lesgourgues

Given $k\ge 2$ and two $k$-graphs ($k$-uniform hypergraphs) $F$ and $H$, an $F$-factor in $H$ is a set of vertex disjoint copies of $F$ that together cover the vertex set of $H$. Lenz and Mubayi were first to study the $F$-factor problems…

Combinatorics · Mathematics 2026-02-02 Shumin Sun

The degree anti-Ramsey number $AR_d(H)$ of a graph $H$ is the smallest integer $k$ for which there exists a graph $G$ with maximum degree at most $k$ such that any proper edge colouring of $G$ yields a rainbow copy of $H$. In this paper we…

Combinatorics · Mathematics 2017-05-15 Shoni Gilboa , Dan Hefetz

An immersion of a graph $H$ into a graph $G$ is a one-to-one mapping $f:V(H) \to V(G)$ and a collection of edge-disjoint paths in $G$, one for each edge of $H$, such that the path $P_{uv}$ corresponding to edge $uv$ has endpoints $f(u)$ and…

Combinatorics · Mathematics 2011-01-14 Matt DeVos , Zdeněk Dvořák , Jacob Fox , Jessica McDonald , Bojan Mohar , Diego Scheide

If $G$ is a graph and $\vec H$ is an oriented graph, we write $G\to \vec H$ to say that every orientation of the edges of $G$ contains $\vec H$ as a subdigraph. We consider the case in which $G=G(n,p)$, the binomial random graph. We…

The Kohayakawa-Nagle-R\"odl-Schacht conjecture roughly states that every sufficiently large locally $d$-dense graph $G$ on $n$ vertices must contain at least $(1-o(1))d^{|E(H)|}n^{|V(H)|}$ copies of a fixed graph $H$. Despite its important…

Combinatorics · Mathematics 2019-08-12 Joonkyung Lee

In 1983, Burr and Erd\H{o}s initiated the study of Ramsey goodness problems.Nikiforov and Rousseau (2009) resolved almost all goodness questions raised by Burr and Erd\H{o}s, in which the bounds on the parameters are of tower type since…

Combinatorics · Mathematics 2022-04-08 Chunchao Fan , Qizhong Lin

Given a graph $H$, the Ramsey number $r(H)$ is the smallest natural number $N$ such that any two-colouring of the edges of $K_N$ contains a monochromatic copy of $H$. The existence of these numbers has been known since 1930 but their…

Combinatorics · Mathematics 2015-05-12 David Conlon , Jacob Fox , Benny Sudakov

A Berge copy of a graph is a hypergraph obtained by enlarging the edges arbitrarily. Gr\'osz, Methuku and Tompkins in 2020 showed that for any graph $F$, there is an integer $r_0=r_0(F)$, such that for any $r\ge r_0$, any $r$-uniform…

Combinatorics · Mathematics 2021-11-02 Dániel Gerbner

Given a graph $H$, let $\chi_H(\mathbb{R}^n)$ be the smallest positive integer $r$ such that there exists an $r$-coloring of $\mathbb{R}^n$ with no monochromatic unit-copy of $H$, that is a set of $|V(H)|$ vertices of the same color such…

Combinatorics · Mathematics 2025-12-19 Maria Axenovich , Dingyuan Liu , Arsenii Sagdeev

We say that a graph $F$ can be embedded into a graph $G$ if $G$ contains an isomorphic copy of $F$ as a subgraph. Guo and Volkmann \cite{GV} conjectured that if $G$ is a connected graph with at least $n$ vertices and minimum degree at least…

Combinatorics · Mathematics 2022-01-03 Zilong Yan , Yuejian Peng

Given a graph $G$ and a positive integer $k$, define the \emph{Gallai-Ramsey number} to be the minimum number of vertices $n$ such that any $k$-edge coloring of $K_n$ contains either a rainbow (all different colored) triangle or a…

Combinatorics · Mathematics 2019-05-30 Yaping Mao , Zhao Wang , Colton Magnant , Ingo Schiermeyer

The $r$-color size-Ramsey number of a $k$-uniform hypergraph $H$, denoted by $\hat{R}_r(H)$, is the minimum number of edges in a $k$-uniform hypergraph $G$ such that for every $r$-coloring of the edges of $G$ there exists a monochromatic…

Combinatorics · Mathematics 2024-03-13 Deepak Bal , Louis DeBiasio , Allan Lo

Let K_4 denote the complete 3-uniform hypergraph on 4 vertices. Ajtai, Erd\H{o}s, Koml\'os, and Szemer\'edi (1981) asked if there is a function \omega(d) tending to infinity such that every 3-uniform, K_4-free hypergraph N vertices and…

Combinatorics · Mathematics 2014-07-24 Jeff Cooper , Dhruv Mubayi

A celebrated result of Chv\'atal, R\"odl, Szemer\'edi and Trotter states (in slightly weakened form) that, for every natural number $\Delta$, there is a constant $r_\Delta$ such that, for any connected $n$-vertex graph $G$ with maximum…

Combinatorics · Mathematics 2010-10-26 Peter Allen , Graham Brightwell , Jozef Skokan

In 1984, Thomassen conjectured that for every constant $k \in \mathbb{N}$, there exists $d$ such that every graph with average degree at least $d$ contains a balanced subdivision of a complete graph on $k$ vertices, i.e. a subdivision in…

Combinatorics · Mathematics 2023-02-09 Yan Wang

Let $d,n\in \mathbb{N}$ be such that $d=\omega(1)$, and $d\le n^{1-a}$ for some constant $a>0$. Consider a $d$-regular graph $G=(V, E)$ and the random graph process that starts with the empty graph $G(0)$ and at each step $G(i)$ is obtained…

Combinatorics · Mathematics 2024-09-25 Sahar Diskin , Anna Geisler

Let $G$ be a $d$-regular graph on $n$ vertices. Frieze, Gould, Karo\'nski and Pfender began the study of the following random spanning subgraph model $H=H(G)$. Assign independently to each vertex $v$ of $G$ a uniform random number $x(v) \in…

Combinatorics · Mathematics 2022-07-28 Jacob Fox , Sammy Luo , Huy Tuan Pham

R\"odl, Ruci\'nski, and Szemer\'edi determined the minimum $(k-1)$-degree threshold for the existence of fractional perfect matchings in $k$-uniform hypergrahs, and K\"uhn, Osthus, and Townsend extended this result by asymptotically…

Combinatorics · Mathematics 2021-04-02 Hongliang Lu , Xingxing Yu
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