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A star edge coloring of a graph $G$ is a proper edge coloring of $G$ such that no path or cycle of length four is bi-colored. The star chromatic index of $G$, denoted by $\chi^{\prime}_{s}(G)$, is the minimum $k$ such that $G$ admits a star…

Combinatorics · Mathematics 2019-11-07 Behnaz Omoomi , Marzieh Vahid Dastjerdi , Yasaman Yektaeian

A 1-removed subgraph $G_f$ of a graph $G=(V,E)$ is obtained by $(i)$ selecting at most one edge $f(v)$ for each vertex $v\in V$, such that $v\in f(v)\in E$ (the mapping $f:V\to E \cup \{\varnothing\}$ is allowed to be non-injective), and…

Combinatorics · Mathematics 2023-06-22 Gábor Bacsó , Balázs Patkós , Zsolt Tuza , Máté Vizer

A graph $G$ is $k$-critical (list $k$-critical, DP $k$-critical) if $\chi(G)= k$ ($\chi_\ell(G)= k$, $\chi_\mathrm{DP}(G)= k$) and for every proper subgraph $G'$ of $G$, $\chi(G')<k$ ($\chi_\ell(G')< k$, $\chi_\mathrm{DP}(G')<k$). Let $f(n,…

Combinatorics · Mathematics 2024-10-03 Peter Bradshaw , Ilkyoo Choi , Alexandr Kostochka , Jingwei Xu

The $\!{}\bmod k$ chromatic index of a graph $G$ is the minimum number of colors needed to color the edges of $G$ in a way that the subgraph spanned by the edges of each color has all degrees congruent to $1\!\!\pmod k$. Recently, the…

Combinatorics · Mathematics 2023-02-28 Fábio Botler , Lucas Colucci , Yoshiharu Kohayakawa

A graph $G$ is \emph{uniquely k-colorable} if the chromatic number of $G$ is $k$ and $G$ has only one $k$-coloring up to permutation of the colors. A uniquely $k$-colorable graph $G$ is edge-critical if $G-e$ is not a uniquely $k$-colorable…

Combinatorics · Mathematics 2013-12-31 Zepeng Li , Enqiang Zhu , Zehui Shao , Jin Xu

A $k$-subcolouring of a graph $G$ is a function $f:V(G) \to \{0,\ldots,k-1\}$ such that the set of vertices coloured $i$ induce a disjoint union of cliques. The subchromatic number, $\chi_{\textrm{sub}}(G)$, is the minimum $k$ such that $G$…

A vertex coloring of a graph is said to be \textit{conflict-free} with respect to neighborhoods if for every non-isolated vertex there is a color appearing exactly once in its (open) neighborhood. As defined in [Fabrici et al.,…

Combinatorics · Mathematics 2022-03-03 Yair Caro , Mirko Petruševski , Riste Škrekovski

A proper coloring of the vertices of a graph is called a \emph{star coloring} if the union of every two color classes induces a star forest. The star chromatic number $\chi_s(G)$ is the smallest number of colors required to obtain a star…

Combinatorics · Mathematics 2021-05-17 Yuehua Bu , Daniel W. Cranston , Mickaël Montassier , André Raspaud , Weifan Wang

A strong edge-coloring of a graph $G$ is an edge-coloring in which every color class is an induced matching, and the strong chromatic index $\chi_s'(G)$ is the minimum number of colors needed in strong edge-colorings of $G$. A graph is…

Combinatorics · Mathematics 2023-01-31 Gexin Yu , Rachel Yu

For a non-decreasing sequence of positive integers $S=(s_1,s_2,\ldots)$, the $S$-packing chromatic number of a graph $G$ is denoted by $\chi_S(G)$. In this paper, $\chi_S$-critical graphs are introduced as the graphs $G$ such that…

Combinatorics · Mathematics 2025-05-26 Gülnaz Boruzanlı Ekinci , Csilla Bujtás , Didem Gözüpek , Sandi Klavžar

A dynamic coloring of a graph $G$ is a proper coloring such that for every vertex $v\in V(G)$ of degree at least 2, the neighbors of $v$ receive at least 2 colors. In this paper we present some upper bounds for the dynamic chromatic number…

Combinatorics · Mathematics 2009-08-19 Meysam Alishahi

Let $H=(V(H),E(H))$ be a graph. A $k$-coloring of $H$ is a mapping $\pi : V(H) \longrightarrow \{1,2,\ldots, k\}$ so that each color class induces a $K_2$-free subgraph. For a graph $G$ of order at least $2$, a $G$-free $k$-coloring of $H$…

Combinatorics · Mathematics 2022-01-21 Yaser Rowshan

The resistance $r(G)$ of a graph $G$ is the minimum number of edges that have to be removed from $G$ to obtain a graph which is $\Delta(G)$-edge-colorable. The paper relates the resistance to other parameters that measure how far is a graph…

Discrete Mathematics · Computer Science 2011-11-17 Vahan Mkrtchyan , Eckhard Steffen

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

The distinguishing number $D(G)$ of a graph $G$ is the least integer $d$ such that $G$ has a vertex labeling with $d$ labels that is preserved only by a trivial automorphism. The distinguishing chromatic number $\chi_{D}(G)$ of $G$ is…

Combinatorics · Mathematics 2017-09-29 Saeid Alikhani , Samaneh Soltani

In a strong edge-coloring of a graph $G=(V,E)$, any two edges of distance at most $2$ get distinct colors. The strong chromatic index of $G$, denoted by $\chi_s'(G)$, is the minimum number of colors needed in a strong edge-coloring of $G$.…

Combinatorics · Mathematics 2026-02-05 Runze Wang

The distinguishing chromatic number, $\chi_D(G)$, of a graph $G$ is the smallest number of colors in a proper coloring, $\varphi$, of $G$, such that the only automorphism of $G$ that preserves all colors of $\varphi$ is the identity map.…

Combinatorics · Mathematics 2018-10-18 Daniel W. Cranston

This paper proves that if $G$ is a graph (parallel edges allowed) of maximum degree 3, then $\chi_c'(G) \leq 11/3$ provided that $G$ does not contain $H_1$ or $H_2$ as a subgraph, where $H_1$ and $H_2$ are obtained by subdividing one edge…

Combinatorics · Mathematics 2009-09-29 Peyman Afshani , Mahsa Ghandehari , Mahya Ghandehari , Hamed Hatami , Ruzbeh Tusserkani , Xuding Zhu

The star chromatic index of a graph $G$, denoted by $\chi'_{st}(G) $, is the minimum number of colors needed to properly color the edges of $G$ such that no path or cycle of length four is bi-colored. Casselgren et al. and Hou et al.…

Combinatorics · Mathematics 2025-11-18 Xingxing Hu , Yunfang Tang

Let $G$ be a simple graph. The dominated coloring of $G$ is a proper coloring of $G$ such that each color class is dominated by at least one vertex. The minimum number of colors needed for a dominated coloring of $G$ is called the dominated…

Combinatorics · Mathematics 2019-10-10 Saeid Alikhani , Mohammad R. Piri