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We present a randomized algorithm that, given a constant $\epsilon > 0$, outputs a proper $(1+\epsilon)\Delta$-edge-coloring of an $m$-edge simple graph $G$ of maximum degree $\Delta \geq 1/\epsilon$ in $O(m)$ time with high probability.…

Data Structures and Algorithms · Computer Science 2025-02-10 Anton Bernshteyn , Abhishek Dhawan

In the minimum sum edge coloring problem, we aim to assign natural numbers to edges of a graph, so that adjacent edges receive different numbers, and the sum of the numbers assigned to the edges is minimum. The {\em chromatic edge strength}…

Discrete Mathematics · Computer Science 2008-01-22 Jean Cardinal , Vlady Ravelomanana , Mario Valencia-Pabon

A coloring is distinguishing (or symmetry breaking) if no non-identity automorphism preserves it. The distinguishing threshold of a graph $G$, denoted by $\theta(G)$, is the minimum number of colors $k$ so that every $k$-coloring of $G$ is…

Combinatorics · Mathematics 2022-12-19 Saeid Alikhani , Mohammad Hadi Shekarriz

Vizing's theorem states that any graph of maximum degree $\Delta$ can be properly edge colored with at most $\Delta+1$ colors. In the online setting, it has been a matter of interest to find an algorithm that can properly edge color any…

Data Structures and Algorithms · Computer Science 2024-10-30 Aditi Dudeja , Rashmika Goswami , Michael Saks

We study two parameters that arise from the dichromatic number and the vertex-arboricity in the same way that the achromatic number comes from the chromatic number. The adichromatic number of a digraph is the largest number of colors its…

Combinatorics · Mathematics 2019-05-22 Stefan Felsner , Winfried Hochstättler , Kolja Knauer , Raphael Steiner

It is known (Bollob\'{a}s (1978); Kostochka and Mazurova (1977)) that there exist graphs of maximum degree $\Delta$ and of arbitrarily large girth whose chromatic number is at least $c \Delta / \log \Delta$. We show an analogous result for…

Combinatorics · Mathematics 2011-10-25 Ararat Harutyunyan , Bojan Mohar

We systematically determine circular chromatic index of small graphs and multigraphs with maximum degree $4$, $5$, $6$ (and also their number for a given small order). We construct several infinite families of such graphs with circular…

Combinatorics · Mathematics 2026-03-11 Ján Mazák , Filip Zrubák

Inspired by the majority colorings and C-colorings, we introduce and study the majority C-coloring of graphs. In such a vertex coloring, every vertex shares its color with at least half of its neighbors. The maximum number of colors that…

Combinatorics · Mathematics 2026-04-23 Csilla Bujtas , Magda Dettlaff , Hanna Furmanczyk , Aleksandra Laskowska

The problem of sampling edge-colorings of graphs with maximum degree $\Delta$ has received considerable attention and efficient algorithms are available when the number of colors is large enough with respect to $\Delta$. Vizing's theorem…

Data Structures and Algorithms · Computer Science 2025-01-22 Lucas De Meyer , František Kardoš , Aurélie Lagoutte , Guillem Perarnau

Let $G$ be a graph. An acyclic $k$-coloring of $G$ is a map $c:V(G)\rightarrow \{1,\dots,k\}$ such that $c(u)\neq c(v)$ for any $uv\in E(G)$ and the subgraph induced by the vertices of any two colors $i,j\in \{1,\dots,k\}$ is a forest. If…

Combinatorics · Mathematics 2025-11-04 Marcin Anholcer , Sylwia Cichacz , Iztok Peterin

Coloring a graph $G$ consists in finding an assignment of colors $c: V(G)\to\{1,\ldots,p\}$ such that any pair of adjacent vertices receives different colors. The minimum integer $p$ such that a coloring exists is called the chromatic…

Discrete Mathematics · Computer Science 2019-12-25 Théo Pierron

An adjacent vertex distinguishing edge colouring of a graph $G$ without isolated edges is its proper edge colouring such that no pair of adjacent vertices meets the same set of colours in $G$. We show that such colouring can be chosen from…

Combinatorics · Mathematics 2019-01-08 Jakub Kwaśny , Jakub Przybyło

We study combinatorial indicators related to the characteristic phase transitions associated with coloring a graph optimally and finding a maximum independent set. In particular, we investigate the role of the acyclic orientations of the…

Statistical Mechanics · Physics 2007-05-23 V. C. Barbosa , R. G. Ferreira

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

\qquad A \emph{coloring} of a digraph $D=(V,E)$ is a coloring of its vertices following the rule: Let $uv$ be an arc in $D$. If the tail $u$ is colored first, then the head $v$ should receive a color different from that of $u$. The…

Combinatorics · Mathematics 2013-04-02 E. Sampathkumar

An \emph{acyclic coloring} of a graph is a proper vertex coloring such that the union of any two color classes induces a disjoint collection of trees. The more restricted notion of \emph{star coloring} requires that the union of any two…

Data Structures and Algorithms · Computer Science 2011-03-30 Andrew Lyons

In this paper we study the {\it {achromatic arboricity}} of the complete graph. This parameter arises from the arboricity of a graph as the achromatic index arises from the chromatic index. The achromatic arboricity of a graph $G$, denoted…

Combinatorics · Mathematics 2021-03-24 Gabriela Araujo-Pardo , Christian Rubio-Montiel

The chromatic number of a graph is the minimum $k$ such that the graph has a proper $k$-coloring. There are many coloring parameters in the literature that are proper colorings that also forbid bicolored subgraphs. Some examples are…

Combinatorics · Mathematics 2018-12-05 Ilkyoo Choi , Ringi Kim , Boram Park

A strong edge-coloring of a graph is a proper edge-coloring, in which the edges of every path of length 3 receive distinct colors; in other words, every pair of edges at distance at most 2 must be colored differently. The least number of…

Combinatorics · Mathematics 2025-12-03 Borut Lužar , Edita Máčajová , Roman Soták , Diana Švecová

A proper coloring of a graph is \emph{conflict-free} if, for every non-isolated vertex, some color is used exactly once on its neighborhood. Caro, Petru\v{s}evski, and \v{S}krekovski proved that every graph $G$ has a proper conflict-free…

Combinatorics · Mathematics 2024-12-16 Daniel W. Cranston , Chun-Hung Liu