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A path in an edge-colored graph is called a monochromatic path if all edges of the path have a same color. We call $k$ paths $P_1,\cdots,P_k$ rainbow monochromatic paths if every $P_i$ is monochromatic and for any two $i\neq j$, $P_i$ and…

Combinatorics · Mathematics 2020-01-07 Ping Li , Xueliang Li

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

We call a (not necessarily properly) edge-colored graph edge-color-avoiding connected if after the removal of edges of any single color, the graph remains connected. For vertex-colored graphs, similar definitions of color-avoiding…

Combinatorics · Mathematics 2024-01-29 József Pintér , Kitti Varga

A graph is called uniquely distinguishing colorable if there is only one partition of vertices of the graph that forms distinguishing coloring with the smallest possible colors. In this paper, we study the unique colorability of the…

Combinatorics · Mathematics 2023-08-16 M. Korivand , N. Soltankhah , K. Khashyarmanesh

The {\em disjointness graph} $G=G({\cal S})$ of a set of segments ${\cal S}$ in $R^d$, $d\ge 2,$ is a graph whose vertex set is ${\cal S}$ and two vertices are connected by an edge if and only if the corresponding segments are disjoint. We…

Combinatorics · Mathematics 2021-11-12 Janos Pach , Gabor Tardos , Geza Toth

An edge-colored graph $G$ is called properly colored if no two adjacent edges share a color in $G$. An edge-colored connected graph $G$ is called properly connected if between every pair of distinct vertices, there exists a path that is…

Combinatorics · Mathematics 2019-03-11 Shinya Fujita

Let $\omega(G)$ and $\chi(G)$ denote the clique number and chromatic number of a graph $G$, respectively. The {\em disjointness graph} of a family of curves (continuous arcs in the plane) is the graph whose vertices correspond to the curves…

Combinatorics · Mathematics 2018-11-26 Janos Pach , Istvan Tomon

Let $G$ be a graph whose edges are coloured with $k$ colours, and $\mathcal H=(H_1,\dots , H_k)$ be a $k$-tuple of graphs. A monochromatic $\mathcal H$-decomposition of $G$ is a partition of the edge set of $G$ such that each part is either…

Combinatorics · Mathematics 2014-12-19 Henry Liu , Oleg Pikhurko , Teresa Sousa

Let $G$ be a nontrivial connected and vertex-colored graph. A subset $X$ of the vertex set of $G$ is called rainbow if any two vertices in $X$ have distinct colors. The graph $G$ is called \emph{rainbow vertex-disconnected} if for any two…

Combinatorics · Mathematics 2020-03-31 Xuqing Bai , You Chen , Ping Li , Xueliang Li , Yindi Weng

In the last years, connection concepts such as rainbow connection and proper connection appeared in graph theory and obtained a lot of attention. In this paper, we investigate the loose edge-connection of graphs. A connected edge-coloured…

Combinatorics · Mathematics 2022-06-24 Christoph Brause , Stanislav Jendrol , Ingo Schiermeyer

We show that the edges of any graph $G$ containing two edge-disjoint spanning trees can be blue/red coloured so that the blue and red graphs are connected and the blue and red degrees at each vertex differ by at most four. This improves a…

Combinatorics · Mathematics 2023-03-31 Freddie Illingworth , Emil Powierski , Alex Scott , Youri Tamitegama

Let $K_{\mathbb{N}}$ be the complete symmetric digraph on the positive integers. Answering a question of DeBiasio and McKenney, we construct a $2$-colouring of the edges of $K_{\mathbb{N}}$ in which every monochromatic path has density~$0$.…

Combinatorics · Mathematics 2018-05-07 Carl Bürger , Louis DeBiasio , Hannah Guggiari , Max Pitz

A graph is said to be {\it total-colored} if all the edges and the vertices of the graph are colored. A total-coloring of a graph is a {\it total monochromatically-connecting coloring} ({\it TMC-coloring}, for short) if any two vertices of…

Combinatorics · Mathematics 2016-04-11 Hui Jiang , Xueliang Li , Yingying Zhang

The concept of rainbow disconnection number of graphs was introduced by Chartrand et al. in 2018. Inspired by this concept, we put forward the concepts of rainbow vertex-disconnection and proper disconnection in graphs. In this paper, we…

Combinatorics · Mathematics 2020-07-30 You Chen , Ping Li , Xueliang Li , Yindi Weng

We present results on partitioning the vertices of $2$-edge-colored graphs into monochromatic paths and cycles. We prove asymptotically the two-color case of a conjecture of S\'ark\"ozy: the vertex set of every $2$-edge-colored graph can be…

Combinatorics · Mathematics 2015-09-21 Jozsef Balogh , Janos Barat , Daniel Gerbner , Andras Gyarfas , GAbor N. Sarkozy

A vertex coloring of a graph $G$ is called distinguishing if no non-identity automorphisms of $G$ can preserve it. The distinguishing number of $G$, denoted by $D(G)$, is the minimum number of colors required for such a coloring, and the…

Let G = (V, E) be a multigraph without loops and for any x {\in}V let E(x) be the set of edges of G incident to x. A homogeneous edge-coloring of G is an assignment of an integer m >= 2 and a coloring c:E {\to} S of the edges of…

Combinatorics · Mathematics 2012-03-21 Paola Bonacini , Maria Grazia Cinquegrani , Lucia Marino

An {\em odd subgraph} of a graph is a subgraph in which every vertex has odd degree. A graph $G$ is said to be {\em odd $k$-edge-colorable} if there exists an edge-coloring $E(G) \rightarrow \{1,2, \ldots, k\}$ such that each non-empty…

Combinatorics · Mathematics 2026-04-20 Mikio Kano , Shun-ichi Maezawa , Kenta Ozeki

An odd graph is a finite graph all of whose vertices have odd degrees. Given graph $G$ is decomposable into $k$ odd subgraphs if its edge set can be partitioned into $k$ subsets each of which induces an odd subgraph of $G$. The minimum…

Combinatorics · Mathematics 2023-03-09 Mirko Petruševski , Riste Škrekovski

For an edge-colored graph $G$, the minimum color degree of $G$ means the minimum number of colors on edges which are adjacent to each vertex of $G$. We prove that if $G$ is an edge-colored graph with minimum color degree at least $5$ then…

Combinatorics · Mathematics 2017-01-12 Ruonan Li , Shinya Fujita , Guanghui Wang