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A strong edge-coloring of a graph $G$ is a coloring of the edges such that every color class induces a matching in $G$. The strong chromatic index of a graph is the minimum number of colors needed in a strong edge-coloring of the graph. In…

Combinatorics · Mathematics 2018-06-20 Mingfang Huang , Michael Santana , Gexin Yu

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 acyclic edge coloring of a graph is a proper edge coloring in which there are no bichromatic cycles. The acyclic chromatic index of a graph $G$ denoted by $a'(G)$, is the minimum positive integer $k$ such that $G$ has an acyclic edge…

Combinatorics · Mathematics 2023-07-06 Manu Basavaraju , Suresh Manjanath Hegde , Shashanka Kulamarva

A proper coloring of a graph is called \emph{odd} if every non-isolated vertex has some color that appears an odd number of times on its neighborhood. The smallest number of colors that admits an odd coloring of a graph $G$ is denoted…

Combinatorics · Mathematics 2024-12-06 Daniel W. Cranston

An asymmetric coloring of a graph is a coloring of its vertices that is not preserved by any non-identity automorphism of the graph. The motion of a graph is the minimal degree of its automorphism group, i.e., the minimum number of elements…

Group Theory · Mathematics 2021-11-16 Laszlo Babai

Given a multigraph, suppose that each vertex is given a local assignment of $k$ colours to its incident edges. We are interested in whether there is a choice of one local colour per vertex such that no edge has both of its local colours…

Combinatorics · Mathematics 2020-10-13 Zdeněk Dvořák , Louis Esperet , Ross J. Kang , Kenta Ozeki

We consider the following extension of the concept of adjacent strong edge colourings of graphs without isolated edges. Two distinct vertices which are at distant at most $r$ in a graph are called $r$-adjacent. The least number of colours…

Combinatorics · Mathematics 2018-03-13 Jakub Przybyło

An \emph{interval $t$-coloring} of a graph $G$ is a proper edge-coloring with colors $1,\dots,t$ such that the colors on the edges incident to every vertex of $G$ are colored by consecutive colors. A graph $G$ is called \emph{interval…

Combinatorics · Mathematics 2024-09-27 Petros A. Petrosyan , Hrant H. Khachatrian , Hovhannes G. Tananyan

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

Irredundance coloring of $G$ is a proper coloring in which there exists a maximal irredundant set $R$ such that all the vertices of $R$ have different colors. The minimum number of colors required for an irredundance coloring of $G$ is…

Combinatorics · Mathematics 2023-11-30 David Ashok Kalarkop , Pawaton Kaemawichanurat

The local chromatic number of a graph G is the number of colors appearing in the most colorful closed neighborhood of a vertex minimized over all proper colorings of G. We show that two specific topological obstructions that have the same…

Combinatorics · Mathematics 2007-05-23 Gábor Simonyi , Gábor Tardos , Siniša T. Vrećica

Proper edge coloring of a graph $G$ is called acyclic if there is no bichromatic cycle in $G$. The acyclic chromatic index of $G$, denoted by $\chi'_a(G)$, is the least number of colors $k$ such that $G$ has an acyclic edge $k$-coloring.…

Combinatorics · Mathematics 2012-03-26 Yue Guan , Jianfeng Hou , Yingyuan Yang

For an undirected, simple, finite, connected graph $G$, we denote by $V(G)$ and $E(G)$ the sets of its vertices and edges, respectively. A function $\varphi:E(G)\rightarrow\{1,2,\ldots,t\}$ is called a proper edge $t$-coloring of a graph…

Discrete Mathematics · Computer Science 2012-05-02 R. R. Kamalian

For a graph $G$ and an integer $k\geq 2$, a $\chi'_{k}$-coloring of $G$ is an edge coloring of $G$ such that the subgraph induced by the edges of each color has all degrees congruent to $1 ~ (\mod k)$, and $\chi'_{k}(G)$ is the minimum…

Combinatorics · Mathematics 2024-11-13 Oothan Nweit , Daqing Yang

A strong edge colouring of a graph is an assignment of colours to the edges of the graph such that for every colour, the set of edges that are given that colour form an induced matching in the graph. The strong chromatic index of a graph…

Combinatorics · Mathematics 2013-08-20 Manu Basavaraju , Mathew C. Francis

Let $H$ be a graph with $\Delta(H) \leq 2$, and let $G$ be obtained from $H$ by gluing in vertex-disjoint copies of $K_4$. We prove that if $H$ contains at most one odd cycle of length exceeding $3$, or if $H$ contains at most $3$…

Combinatorics · Mathematics 2021-07-08 Jessica McDonald , Gregory J. Puleo

In this paper, we prove that every 3-chromatic connected graph, except $C_7$, admits a 3-vertex coloring in which every vertex is the beginning of a 3-chromatic path. It is a special case of a conjecture due to S.~Akbari, F.~Khaghanpoor,…

Combinatorics · Mathematics 2015-03-04 Bessy Stéphane , Bousquet Nicolas

A colouring of a graph G is called distinguishing if its stabiliser in Aut G is trivial. It has been conjectured that, if every automorphism of a locally finite graph moves infinitely many vertices, then there is a distinguishing…

Combinatorics · Mathematics 2013-04-25 Florian Lehner

A graph is called 1-planar if it can be drawn on the plane so that each edge is crossed by at most one other edge. In this paper, we establish a local property of 1-planar graphs which describes the structure in the neighborhood of small…

Discrete Mathematics · Computer Science 2011-01-04 Xin Zhang , Guizhen Liu , Jian-Liang Wu

A vertex colouring of a graph is called asymmetric if the only automorphism which preserves it is the identity. Tucker conjectured that if every automorphism of a connected, locally finite graph moves infinitely many vertices, then there is…

Combinatorics · Mathematics 2020-07-21 Florian Lehner , Monika Pilśniak , Marcin Stawiski