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Given an infinite family ${\mathcal G}$ of graphs and a monotone property ${\mathcal P}$, an (upper) threshold for ${\mathcal G}$ and ${\mathcal P}$ is a "fastest growing" function $p: \mathbb{N} \to [0,1]$ such that $\lim_{n \to \infty}…

Combinatorics · Mathematics 2024-12-16 Chun-Hung Liu , Fan Wei

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

Two (proper) colorings of a graph are adjacent if they differ on exactly one vertex. Jerrum proved that any $(d + 2)$-coloring of any d-degenerate graph can be transformed into any other via a sequence of adjacent colorings. A result of…

Discrete Mathematics · Computer Science 2020-12-22 Valentin Bartier , Nicolas Bousquet , Marc Heinrich

An injective coloring of a graph is a vertex coloring where two vertices with common neighbor receive distinct colors. The minimum integer $k$ that $G$ has a $k-$injective coloring is called injective chromatic number of $G$ and denoted by…

Combinatorics · Mathematics 2017-06-09 Mahsa Mozafari-Nia , Behnaz Omoomi

The Grundy number of a graph is the minimum number of colors needed to properly color the graph using the first-fit greedy algorithm regardless of the initial vertex ordering. Computing the Grundy number of a graph is an NP-Hard problem.…

Combinatorics · Mathematics 2024-01-24 Thiago Assis , Gabriel Coutinho , Emanuel Juliano

A {\em conflict-free coloring} of a graph {\em with respect to open} (resp., {\em closed}) {\em neighborhood} is a coloring of vertices such that for every vertex there is a color appearing exactly once in its open (resp., closed)…

Combinatorics · Mathematics 2022-10-11 Igor Fabrici , Borut Lužar , Simona Rindošová , Roman Soták

For integers $k>0$ and $0<r \leq \Delta$ (where $r \leq k$), a conditional $(k,r)$-coloring of a graph $G$ is a proper $k$-coloring of the vertices of $G$ such that every vertex $v$ of degree $d(v)$ in $G$ is adjacent to vertices with at…

Discrete Mathematics · Computer Science 2012-01-31 P. V. Subba Reddy , K. V. Iyer

We study weighted edge coloring of graphs, where we are given an undirected edge-weighted general multi-graph $G := (V, E)$ with weights $w : E \rightarrow [0, 1]$. The goal is to find a proper weighted coloring of the edges with as few…

Data Structures and Algorithms · Computer Science 2021-01-01 Debarsho Sannyasi

Given a graph $G$ and an integer $p$, a coloring $f : V(G) \to \mathbb{N}$ is \emph{$p$-centered} if for every connected subgraph $H$ of $G$, either $f$ uses more than $p$ colors on $H$ or there is a color that appears exactly once in $H$.…

Combinatorics · Mathematics 2023-06-22 Loïc Dubois , Gwenaël Joret , Guillem Perarnau , Marcin Pilipczuk , François Pitois

An identifying code of a graph is a subset of its vertices such that every vertex of the graph is uniquely identified by the set of its neighbours within the code. We study the edge-identifying code problem, i.e. the identifying code…

Combinatorics · Mathematics 2014-03-19 Florent Foucaud , Sylvain Gravier , Reza Naserasr , Aline Parreau , Petru Valicov

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 adjacent vertex distinguishing coloring of a graph G is a proper edge coloring of G such that any pair of adjacent vertices are incident with distinct sets of colors. The minimum number of colors needed for an adjacent vertex…

Combinatorics · Mathematics 2012-08-14 Lianzhu Zhang , Weifan Wang , Ko-Wei Lih

We introduce weak oddness $\omega_{\textrm w}$, a new measure of uncolourability of cubic graphs, defined as the least number of odd components in an even factor. For every bridgeless cubic graph $G$, $\rho(G)\le\omega_{\textrm…

Discrete Mathematics · Computer Science 2016-02-10 Robert Lukoťka , Ján Mazák

We give an online algorithm that with high probability computes a $\left(\frac{e}{e-1} + o(1)\right)\Delta$ edge coloring on a graph $G$ with maximum degree $\Delta = \omega(\log n)$ under online edge arrivals against oblivious adversaries,…

Data Structures and Algorithms · Computer Science 2021-11-02 Janardhan Kulkarni , Yang P. Liu , Ashwin Sah , Mehtaab Sawhney , Jakub Tarnawski

We define a weakly threshold sequence to be a degree sequence $d=(d_1,\dots,d_n)$ of a graph having the property that $\sum_{i \leq k} d_i \geq k(k-1)+\sum_{i > k} \min\{k,d_i\} - 1$ for all positive $k \leq \max\{i:d_i \geq i-1\}$. The…

Combinatorics · Mathematics 2023-06-22 Michael D. Barrus

Given an $r$-uniform hypergraph $H=(V,E)$ and a weight function $\omega:E\to\{1,\dots,w\}$, a coloring of vertices of $H$, induced by $\omega$, is defined by $c(v) = \sum_{e\ni v} w(e)$ for all $v\in V$. If there exists such a coloring that…

Combinatorics · Mathematics 2015-12-11 Patrick Bennett , Andrzej Dudek , Alan Frieze , Laars Helenius

Motivated by recent work on majority edge-colourings of graphs, we initiate the study of the corresponding problem for hypergraphs. First, sharpening the probabilistic argument by a $KL$ large-deviation estimate, we obtain a sufficient…

Combinatorics · Mathematics 2026-03-31 Jiangdong Ai , Feiyu Nan

A {\em strong edge coloring} of a graph is a proper edge coloring in which every color class is an induced matching. The {\em strong chromatic index} of a graph is the minimum number of colors needed to obtain a strong edge coloring. In an…

Combinatorics · Mathematics 2017-04-17 Watcharintorn Ruksasakchai , Tao Wang

We prove that in sparse Erd\H{o}s-R\'{e}nyi graphs of average degree $d$, the vector chromatic number (the relaxation of chromatic number coming from the Lov\`{a}sz theta function) is typically $\tfrac{1}{2}\sqrt{d} + o_d(1)$. This fits…

Computational Complexity · Computer Science 2019-07-08 Jess Banks , Luca Trevisan

We prove that for all graphs with at most $(3.75-o(1))n$ edges there exists a 2-coloring of the edges such that every monochromatic path has order less than $n$. This was previously known to be true for graphs with at most $2.5n-7.5$ edges.…

Combinatorics · Mathematics 2021-11-05 Deepak Bal , Louis DeBiasio