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A subgraph of an edge-coloured graph is called rainbow if all its edges have different colours. We prove a rainbow version of the blow-up lemma of Koml\'os, S\'ark\"ozy and Szemer\'edi that applies to almost optimally bounded colourings. A…

Combinatorics · Mathematics 2019-07-24 Stefan Ehard , Stefan Glock , Felix Joos

Let $f(n,r,k)$ be the minimal number such that every hypergraph larger than $f(n,r,k)$ contained in $\binom{[n]}{r}$ contains a matching of size $k$, and let $g(n,r,k)$ be the minimal number such that every hypergraph larger than $g(n,r,k)$…

Combinatorics · Mathematics 2016-05-24 Ron Aharoni , David Howard

An edge-colouring of a graph $G$ can fail to be rainbow for two reasons: either it contains a monochromatic cherry (a pair of incident edges), or a monochromatic matching of size two. A colouring is a proper colouring if it forbids the…

Combinatorics · Mathematics 2025-11-18 Allan Lo , Klas Markström , Dhruv Mubayi , Katherine Staden , Maya Stein , Lea Weber

The anti-Ramsey number, $ar(G, H)$ is the minimum integer $k$ such that in any edge colouring of $G$ with $k$ colours there is a rainbow subgraph isomorphic to $H$, i.e., a copy of $H$ with each of its edges assigned a different colour. The…

Discrete Mathematics · Computer Science 2019-10-28 L Sunil Chandran , Abhiruk Lahiri , Nitin Singh

For graphs $G$ and $H$, let $G {\displaystyle\smash{\begin{subarray}{c} \hbox{$\tiny\rm rb$} \\ \longrightarrow \\ \hbox{$\tiny\rm p$} \end{subarray}}}H$ denote the property that for every proper edge-colouring of $G$ there is a rainbow $H$…

Combinatorics · Mathematics 2023-01-20 Yoshiharu Kohayakawa , Guilherme Oliveira Mota , Olaf Parczyk , Jakob Schnitzer

A graph is said to be \emph{total-colored} if all the edges and the vertices of the graph are colored. A total-colored graph is \emph{total-rainbow connected} if any two vertices of the graph are connected by a path whose edges and internal…

Combinatorics · Mathematics 2017-03-31 Wenjing Li , Xueliang Li , Colton Magnant , Jingshu Zhang

An edge-colored graph is called rainbow if all the colors on its edges are distinct. Given a positive integer n and a graph G, the anti-Ramsey number ar(n,G) is the maximum number of colors in an edge-coloring of K_{n} with no rainbow copy…

Combinatorics · Mathematics 2022-01-12 Fangfang Wu , Shenggui Zhang , Binlong Li , Jimeng Xiao

A path in an edge-colored graph is called {\em rainbow} if no two edges of it are colored the same. For an $\ell$-connected graph $G$ and an integer $k$ with $1\leq k\leq \ell$, the {\em rainbow $k$-connection number} $rc_k(G)$ of $G$ is…

Combinatorics · Mathematics 2012-04-12 Xueliang Li , Sujuan Liu

The rainbow Tur\'an number $\mathrm{ex}^*(n,H)$ of a graph $H$ is the maximum possible number of edges in a properly edge-coloured $n$-vertex graph with no rainbow subgraph isomorphic to $H$. We prove that for any integer $k\geq 2$,…

Combinatorics · Mathematics 2021-04-13 Oliver Janzer

A path in an edge-coloured graph is called \emph{rainbow path} if its edges receive pairwise distinct colours. An edge-coloured graph is said to be \emph{rainbow connected} if any two distinct vertices of the graph are connected by a…

Combinatorics · Mathematics 2019-11-05 Trung Duy Doan , Ingo Schiermeyer

An edge-colored graph $G$ is rainbow connected if every pair of vertices of $G$ are connected by a path whose edges have distinct colors. The rainbow connection number $rc(G)$ of $G$ is defined to be the minimum integer $t$ such that there…

Combinatorics · Mathematics 2012-11-06 Xueliang Li , Sujuan Liu

The rainbow connection number of a graph G is the least number of colours in a (not necessarily proper) edge-colouring of G such that every two vertices are joined by a path which contains no colour twice. Improving a result of Caro et al.,…

A subgraph of an edge-coloured complete graph is called rainbow if all its edges have different colours. The study of rainbow decompositions has a long history, going back to the work of Euler on Latin squares. In this paper we discuss…

Combinatorics · Mathematics 2018-03-20 Alexey Pokrovskiy , Benny Sudakov

In this work, we investigate the fewest number of colors needed to guarantee a rainbow solution to the equation $x_1 + x_2 = k x_3$ in $\mathbb{Z}_n$. This value is called the Rainbow number and is denoted by $rb(\mathbb{Z}_n, k)$ for…

Combinatorics · Mathematics 2018-09-13 Erin Bevilacqua , Samuel King , Jürgen Kritschgau , Michael Tait , Suzannah Tebon , Michael Young

An edge-coloured graph $G$ is rainbow connected if there exists a rainbow path between any two vertices. A graph $G$ is said to be $k$-rainbow connected if there exists an edge-colouring of $G$ with at most $k$ colours that is rainbow…

Combinatorics · Mathematics 2015-06-11 Allan Lo

Given a graph $H$, we say that a graph $G$ is properly rainbow $H$-saturated if: (1) There is a proper edge colouring of $G$ containing no rainbow copy of $H$; (2) For every $e \notin E(G)$, every proper edge colouring of $G+e$ contains a…

Combinatorics · Mathematics 2024-10-15 Andrew Lane , Natasha Morrison

Rainbow connection number rc(G) of a connected graph G is the minimum number of colours needed to colour the edges of G, so that every pair of vertices is connected by at least one path in which no two edges are coloured the same. In this…

Combinatorics · Mathematics 2012-02-21 L. Sunil Chandran , Anita Das , Deepak Rajendraprasad , Nithin M. Varma

The rainbow Tur{\'a}n number of a fixed graph $H$, denoted by ${\text{ex}}^*(n,H)$, is the maximum number of edges in an $n$-vertex graph such that it admits a proper edge coloring with no rainbow $H$. We study this problem in planar…

Combinatorics · Mathematics 2025-11-07 Xiaonan Liu

Let $k>1$, and let $\mathcal{F}$ be a family of $2n+k-3$ non-empty sets of edges in a bipartite graph. If the union of every $k$ members of $\mathcal{F}$ contains a matching of size $n$, then there exists an $\mathcal{F}$-rainbow matching…

Combinatorics · Mathematics 2021-12-30 Ron Aharoni , Joseph Briggs , Minho Cho , Jinha Kim

We study the rainbow version of the graph commonness property: a graph $H$ is $r$-rainbow common if the number of rainbow copies of $H$ (where all edges have distinct colors) in an $r$-coloring of edges of $K_n$ is maximized asymptotically…

Combinatorics · Mathematics 2024-07-11 Yihang Sun
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