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A subgraph of an edge-coloured graph is called rainbow if all its edges have distinct colours. Our main result implies that, given any optimal colouring of a sufficiently large complete graph $K_{2n}$, there exists a decomposition of…

Combinatorics · Mathematics 2020-03-09 Stefan Glock , Daniela Kühn , Richard Montgomery , Deryk Osthus

Motivated by a problem in theoretical computer science suggested by Wigderson, Alon and Ben-Eliezer studied the following extremal problem systematically one decade ago. Given a graph $H$, let $C(n,H)$ be the minimum number $k$ such that…

Combinatorics · Mathematics 2023-02-06 Xinbu Cheng , Zixiang Xu

An edge-colored multigraph $G$ is rainbow connected if every pair of vertices is joined by at least one rainbow path, i.e., a path where no two edges are of the same color. In the context of multilayered networks we introduce the notion of…

Combinatorics · Mathematics 2025-03-04 Josep Díaz , Öznur Yaşar Diner , Maria Serna , Oriol Serra

Let $G$ be a graph of order $n$ with an edge-coloring $c$, and let $\delta^c(G)$ denote the minimum color degree of $G$. A subgraph $F$ of $G$ is called rainbow if all edges of $F$ have pairwise distinct colors. There have been a lot…

Combinatorics · Mathematics 2020-10-23 Xiaozheng Chen , Xueliang Li

A graph has a locating rainbow coloring if every pair of its vertices can be connected by a path passing through internal vertices with distinct colors and every vertex generates a unique rainbow code. The minimum number of colors needed…

Combinatorics · Mathematics 2024-10-15 Ariestha Widyastuty Bustan , A. N. M Salman , Pritta Etriana Putri

Let $G = (V, E)$ be an $n$-vertex edge-colored graph. In 2013, H. Li proved that if every vertex $v \in V$ is incident to at least $(n+1)/2$ distinctly colored edges, then $G$ admits a rainbow triangle. We establish a corresponding result…

Combinatorics · Mathematics 2019-12-05 Andrzej Czygrinow , Theodore Molla , Brendan Nagle , Roy Oursler

Let $G$ be an edge-colored graph on $n$ vertices. For a vertex $v$, the \emph{color degree} of $v$ in $G$, denoted by $d^c(v)$, is the number of colors appearing on the edges incident with $v$. Denote by $\delta^c(G)=\min\{d^c(v):v\in…

Combinatorics · Mathematics 2025-10-14 Xiaozheng Chen , Bo Ning

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

Given a family $\mathcal G$ of graphs on a common vertex set $X$, we say that $\mathcal G$ is rainbow connected if for every vertex pair $u,v \in X$, there exists a path from $u$ to $v$ that uses at most one edge from each graph in…

Combinatorics · Mathematics 2021-07-15 Peter Bradshaw , Bojan Mohar

Let $G$ be an edge-colored graph. We use $e(G)$ and $c(G)$ to denote the number of edges of $G$ and the number of colors appearing on $E(G)$, respectively. For a vertex $v\in V(G)$, the \emph{color neighborhood} of $v$ is defined as the set…

Combinatorics · Mathematics 2019-05-07 Shinya Fujita , Bo Ning , Chuandong Xu , Shenggui Zhang

An edge-colored graph $G$ is rainbow connected if any two vertices are connected by a path whose edges have distinct colors. The rainbow connection number of a connected graph $G$, denoted by $rc(G)$, is the smallest number of colors that…

Combinatorics · Mathematics 2011-10-07 Jiuying Dong , Xueliang Li

A path in an edge colored graph is said to be a rainbow path if no two edges on the path have the same color. An edge colored graph is (strongly) rainbow connected if there exists a (geodesic) rainbow path between every pair of vertices.…

Discrete Mathematics · Computer Science 2011-10-10 Prabhanjan Ananth , Meghana Nasre , Kanthi K Sarpatwar

A rainbow subgraph in an edge-coloured graph is a subgraph such that its edges have distinct colours. The minimum colour degree of a graph is the smallest number of distinct colours on the edges incident with a vertex over all vertices.…

Combinatorics · Mathematics 2012-07-11 Allan Lo , Ta Sheng Tan

An edge-colored graph $G$ is said to be rainbow connected if between each pair of vertices there exists a path which uses each color at most once. The rainbow connection number, denoted by $rc(G)$, is the minimum number of colors needed to…

Discrete Mathematics · Computer Science 2015-10-14 Eduard Eiben , Robert Ganian , Juho Lauri

A rainbow subgraph of an edge-coloured graph has all edges of distinct colours. A random d-regular graph with d even, and having edges coloured randomly with d/2 of each of n colours, has a rainbow Hamilton cycle with probability tending to…

Combinatorics · Mathematics 2007-05-23 Svante Janson , Nicholas Wormald

A famous conjecture of Caccetta and H\"{a}ggkvist (CHC) states that a directed graph $D$ with $n$ vertices and minimum outdegree at least $r$ has a directed cycle of length at most $\lceil \frac{n}{r}\rceil$. In 2017, Aharoni proposed the…

Combinatorics · Mathematics 2023-11-22 Xiaozheng Chen , Shanshan Guo , Fei Huang

An edge-colored graph $G$, where adjacent edges may have the same color, is {\it rainbow connected} if every two vertices of $G$ are connected by a path whose edge has distinct colors. A graph $G$ is {\it $k$-rainbow connected} if one can…

Combinatorics · Mathematics 2012-03-15 Hengzhe Li , Xueliang Li , Yuefang Sun , Yan Zhao

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

Combinatorics · Mathematics 2012-09-12 Manu Basavaraju , L. Sunil Chandran , Deepak Rajendraprasad , Arunselvan Ramaswamy

An edge-colored graph $G$ is rainbow connected if any two vertices are connected by a path whose edges have distinct colors. The rainbow connection number of a connected graph $G$, denoted by $rc(G)$, is the smallest number of colors that…

Computational Complexity · Computer Science 2011-11-15 Xiaolong Huang , Xueliang Li , Yongtang Shi

A path in an edge-colored graph is called a \emph{rainbow path} if all edges on it have pairwise distinct colors. For $k\geq 1$, the \emph{rainbow-$k$-connectivity} of a graph $G$, denoted $rc_k(G)$, is the minimum number of colors required…

Combinatorics · Mathematics 2012-03-06 Jing He , Hongyu Liang