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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 prove that the same hypothesis…

Combinatorics · Mathematics 2021-02-24 Andrzej Czygrinow , Theodore Molla , Brendan Nagle , Roy Oursler

Let $G$ be a finite non-abelian group. The non-commuting graph $\Gamma_G$ of $G$ has the vertex set $G\setminus Z(G)$ and two distinct vertices $x$ and $y$ are adjacent if $xy\ne yx$, where $Z(G)$ is the center of $G$. We prove that the…

Combinatorics · Mathematics 2015-06-16 Yulong Wei , Xuanlong Ma , Kaishun Wang

The rainbow connection number $rc(G)$ and the rainbow vertex-connection number $rvc(G)$ of a graph $G$ were introduced by Chartrand et al. and Krivelevich and Yuster, respectively. Good upper bounds in terms of minimum degree $\delta$ were…

Combinatorics · Mathematics 2011-03-22 Jiuying Dong , Xueliang Li

A tree $T$, in an edge-colored graph $G$, is called {\em a rainbow tree} if no two edges of $T$ are assigned the same color. A {\em $k$-rainbow coloring}of $G$ is an edge coloring of $G$ having the property that for every set $S$ of $k$…

Combinatorics · Mathematics 2014-03-05 Tingting Liu , Yumei Hu

In this short note, we present a purely entropic proof that in a $3$-edge-colored simple graph with $R$ red edges, $G$ green edges, and $B$ blue edges, the number of rainbow triangles is at most $\sqrt{2RGB}$.

Combinatorics · Mathematics 2024-07-22 Ting-Wei Chao , Hung-Hsun Hans Yu

An edge-colored graph $G$ is conflict-free connected if any two of its vertices are connected by a path, which contains a color used on exactly one of its edges. The conflict-free connection number of a connected graph $G$, denoted by…

Combinatorics · Mathematics 2020-12-10 Jing Wang , Meng Ji

Given a graph $G$ and a coloring of its edges, a subgraph of $G$ is called rainbow if its edges have distinct colors. The rainbow girth of an edge coloring of G is the minimum length of a rainbow cycle in G. A generalization of the famous…

Combinatorics · Mathematics 2024-09-25 Ron Aharoni , He Guo

A rainbow spanning tree in an edge-colored graph is a spanning tree in which each edge is a different color. Carraher, Hartke, and Horn showed that for $n$ and $C$ large enough, if $G$ is an edge-colored copy of $K_n$ in which each color…

Combinatorics · Mathematics 2017-04-04 Paul Horn , Lauren M. Nelsen

A graph is said to be {\it total-colored} if all the edges and vertices of the graph are colored. A path in a total-colored graph is a {\it total proper path} if $(i)$ any two adjacent edges on the path differ in color, $(ii)$ any two…

Combinatorics · Mathematics 2017-05-09 Yingying Zhang , Xiaoyu Zhu

A path in a vertex-colored graph is called {\it conflict-free} if there is a color used on exactly one of its vertices. A vertex-colored graph is said to be {\it conflict-free vertex-connected} if any two vertices of the graph are connected…

Combinatorics · Mathematics 2017-09-06 Zhenzhen Li , Baoyindureng Wu

An $r$-regular graph is an $r$-graph, if every odd set of vertices is connected to its complement by at least $r$ edges. Let $G$ and $H$ be $r$-graphs. An $H$-coloring of $G$ is a mapping $f\colon E(G) \to E(H)$ such that each $r$ adjacent…

Combinatorics · Mathematics 2023-05-16 Yulai Ma , Davide Mattiolo , Eckhard Steffen , Isaak H. Wolf

A hypergraph $H$ is properly colored if for every vertex $v\in V(H)$, all the edges incident to $v$ have distinct colors. In this paper, we show that if $H_{1}$, \cdots, $H_{s}$ are properly-colored $k$-uniform hypergraphs on $n$ vertices,…

Combinatorics · Mathematics 2018-08-16 Hao Huang , Tong Li , Guanghui Wang

A properly edge-colored graph is a graph with a coloring of its edges such that no vertex is incident to two or more edges of the same color. A subgraph is called rainbow if all its edges have different colors. The problem of finding…

Combinatorics · Mathematics 2024-12-19 Benny Sudakov

For a connected graph, we define the proper-walk connection number as the minimum number of colors needed to color the edges of a graph so that there is a walk between every pair of vertices without two consecutive edges having the same…

Combinatorics · Mathematics 2017-04-25 Robert Melville , Wayne Goddard

The proper connection number $pc(G)$ of a connected graph $G$ is defined as the minimum number of colors needed to color its edges, so that every pair of distinct vertices of $G$ is connected by at least one path in $G$ such that no two…

Combinatorics · Mathematics 2015-01-26 Xueliang Li , Meiqin Wei , Jun Yue

We study a new variant of \emph{connected coloring} of graphs based on the concept of \emph{strong} edge coloring (every color class forms an \emph{induced} matching). In particular, an edge-colored path is \emph{strongly proper} if its…

A path $P$ in an edge-colored graph $G$ is called a proper path if no two adjacent edges of $P$ are colored the same, and $G$ is proper connected if every two vertices of $G$ are connected by a proper path in $G$. The proper connection…

Combinatorics · Mathematics 2015-04-30 Fei Huang , Xueliang Li , Shujing Wang

In a properly edge colored graph, a subgraph using every color at most once is called rainbow. In this thesis, we study rainbow cycles and paths in proper edge colorings of complete graphs, and we prove that in every proper edge coloring of…

Discrete Mathematics · Computer Science 2012-07-05 Heidi Gebauer , Frank Mousset

A path $P$ in an edge-colored graph is called \emph{a conflict-free path} if there exists a color used on only one of the edges of $P$. An edge-colored graph $G$ is called \emph{conflict-free connected} if for each pair of distinct vertices…

Combinatorics · Mathematics 2019-01-25 Meng Ji , Xueliang Li

Given a vertex-colored graph, we say a path is a rainbow vertex path if all its internal vertices have distinct colors. The graph is rainbow vertex-connected if there is a rainbow vertex path between every pair of its vertices. In the…

Discrete Mathematics · Computer Science 2020-05-12 Paloma T. Lima , Erik Jan van Leeuwen , Marieke van der Wegen