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An $r$-edge coloring of a graph or hypergraph $G=(V,E)$ is a map $c:E\to \{0, \dots, r-1\}$. Extending results of Rado and answering questions of Rado, Gy\'arf\'as and S\'ark\"ozy we prove that (1.) the vertex set of every $r$-edge colored…

Combinatorics · Mathematics 2016-01-07 M. Elekes , D. T. Soukup , L. Soukup , Z. Szentmiklóssy

A tree in an edge-colored connected graph $G$ is called \emph{a rainbow tree} if no two edges of it are assigned the same color. For a vertex subset $S\subseteq V(G)$, a tree is called an \emph{$S$-tree} if it connects $S$ in $G$. A…

Combinatorics · Mathematics 2016-10-20 Wenjing Li , Xueliang Li , Jingshu Zhang

Given a multi-hypergraph $G$ that is edge-colored into color classes $E_1, \ldots, E_n$, a full rainbow matching is a matching of $G$ that contains exactly one edge from each color class $E_i$. One way to guarantee the existence of a full…

Combinatorics · Mathematics 2025-12-19 Ronen Wdowinski

In 1959 Erd\H{o}s and Gallai proved the asymptotically optimal bound for the maximum number of edges in graphs not containing a path of a fixed length. Here we study a rainbow version of their theorem, in which one considers $k \geq 1$…

Combinatorics · Mathematics 2024-01-12 Sebastian Babiński , Andrzej Grzesik

A tree $T$ in an edge-colored graph is a {\it proper tree} if no two adjacent edges of $T$ receive the same color. Let $G$ be a connected graph of order $n$ and $k$ be a fixed integer with $2\le k\le n$. For a vertex subset $S \subseteq…

Combinatorics · Mathematics 2016-03-30 Hong Chang , Xueliang Li , Zhongmei Qin

Rainbow coloring is a special case of edge coloring, where there must be at least one path between every distinct pair of vertices that consists of different color edges. Here, we may use the same color for the adjacent edges of a graph…

Data Structures and Algorithms · Computer Science 2020-01-01 Debasis Dwibedy , Rakesh Mohanty , Arun Khamari

A coloring $c$ of the vertices of a graph $G$ is nonrepetitive if there exists no path $v_1v_2\ldots v_{2l}$ for which $c(v_i)=c(v_{l+i})$ for all $1\le i\le l$. Given graphs $G$ and $H$ with $|V(H)|=k$, the lexicographic product $G[H]$ is…

Combinatorics · Mathematics 2013-09-17 Balázs Keszegh , Balázs Patkós , Xuding Zhu

We prove that every properly edge-colored $n$-vertex graph with average degree at least $100(\log n)^2$ contains a rainbow cycle, improving upon $(\log n)^{2+o(1)}$ bound due to Tomon. We also prove that every properly colored $n$-vertex…

Combinatorics · Mathematics 2022-11-08 Jaehoon Kim , Joonkyung Lee , Hong Liu , Tuan Tran

The reconfiguration graph $R_k(G)$ of the $k$-colourings of a graph~$G$ has as vertex set the set of all possible $k$-colourings of $G$ and two colourings are adjacent if they differ on exactly one vertex. We give a short proof of the…

Combinatorics · Mathematics 2020-12-15 Carl Feghali

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.,…

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

Combinatorics · Mathematics 2012-10-03 Alan Frieze , Charalampos E. Tsourakakis

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

For a fixed graph $F$ and an integer $t$, the \dfn{rainbow saturation number} of $F$, denoted by $sat_t(n,\mathfrak{R}(F))$, is defined as the minimum number of edges in a $t$-edge-colored graph on $n$ vertices which does not contain a…

Combinatorics · Mathematics 2020-01-20 Shujuan Cao , Yuede Ma , Zhenyu Taoqiu

Let $F$ be a fixed graph. The rainbow Tur\'an number of $F$ is defined as the maximum number of edges in a graph on $n$ vertices that has a proper edge-coloring with no rainbow copy of $F$ (where a rainbow copy of $F$ means a copy of $F$…

Combinatorics · Mathematics 2018-05-14 Beka Ergemlidze , Ervin Győri , Abhishek Methuku

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

A subgraph in an edge-colored graph is called rainbow if all its edges have distinct colors. For a graph $G$ and an integer $n$, the anti-Ramsey number $AR(n,G)$ is the maximum number of colors in an edge-coloring of $K_n$ that contains no…

Combinatorics · Mathematics 2026-05-14 Ali Ghalavand , Xueliang Li

For a graph $G$, we define $\sigma_2(G)=min \{d(u)+d(v)| u,v\in V(G), uv\not\in E(G)\}$, or simply denoted by $\sigma_2$. A edge-colored graph is rainbow edge-connected if any two vertices are connected by a path whose edges have distinct…

Combinatorics · Mathematics 2011-01-18 Jiuying Dong , Xueliang Li

A path in a vertex-colored graph is a {\it vertex-proper path} if any two internal adjacent vertices differ in color. A vertex-colored graph is {\it proper vertex $k$-connected} if any two vertices of the graph are connected by $k$ disjoint…

Combinatorics · Mathematics 2015-05-20 Hui Jiang , Xueliang Li , Yingying Zhang , Yan Zhao

Let $G$ be a graph and $R\subseteq V(G)$. A proper edge-coloring of a graph $G$ with colors $1,\ldots,t$ is called an $R$-sequential $t$-coloring if the edges incident to each vertex $v\in R$ are colored by the colors $1,\ldots,d_{G}(v)$,…

Combinatorics · Mathematics 2014-01-07 Petros A. Petrosyan

An edge-coloring of a graph $G$ with colors $1,2,\ldots,t$ is called an interval $t$-coloring if for each $i\in \{1,2,\ldots,t\}$ there is at least one edge of $G$ colored by $i$, and the colors of edges incident to any vertex of $G$ are…

Discrete Mathematics · Computer Science 2010-08-13 R. R. Kamalian , P. A. Petrosyan