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A \textit{locally identifying coloring} ($lid$-coloring) of a graph is a proper coloring such that the sets of colors appearing in the closed neighborhoods of any pair of adjacent vertices having distinct neighborhoods are distinct. Our…

Combinatorics · Mathematics 2014-06-17 Méziane Aïder , Sylvain Gravier , Souad Slimani

We introduce the concept of deficiency in signed graphs. The deficiency of a coloration is the number of unused colors. We classify the deficiency of 2-chromatic graphs. There are four decision problems about the minimum and maximum…

Combinatorics · Mathematics 2020-06-01 Amelia R. W. Mattern

Split-plot designs find wide applicability in multifactor experiments with randomization restrictions. Practical considerations often warrant the use of unbalanced designs. This paper investigates randomization based causal inference in…

Methodology · Statistics 2019-06-21 Rahul Mukerjee , Tirthankar Dasgupta

A graph G is (a:b)-colorable if there exists an assignment of b-element subsets of {1,...,a} to vertices of G such that sets assigned to adjacent vertices are disjoint. We first show that for every triangle-free planar graph G and a vertex…

Combinatorics · Mathematics 2018-09-17 Zdeněk Dvořák , Xiaolan Hu

We define the independence ratio and the chromatic number for bounded, self-adjoint operators on an L^2-space by extending the definitions for the adjacency matrix of finite graphs. In analogy to the Hoffman bounds for finite graphs, we…

Functional Analysis · Mathematics 2014-10-07 Christine Bachoc , Evan DeCorte , Fernando Mario de Oliveira Filho , Frank Vallentin

The Colour Refinement procedure and its generalisation to higher dimensions, the Weisfeiler-Leman algorithm, are central subroutines in approaches to the graph isomorphism problem. In an iterative fashion, Colour Refinement computes a…

Discrete Mathematics · Computer Science 2020-05-21 Sandra Kiefer , Brendan D. McKay

We propose a notion of graph convergence that interpolates between the Benjamini--Schramm convergence of bounded degree graphs and the dense graph convergence developed by L\'aszl\'o Lov\'asz and his coauthors. We prove that spectra of…

Combinatorics · Mathematics 2017-12-27 Péter E. Frenkel

We study the list-chromatic number and the coloring number of graphs, especially uncountable graphs. We show that the coloring number of a graph coincides with its list-chromatic number provided that the diamond principle holds. Under the…

Logic · Mathematics 2021-12-30 Toshimichi Usuba

Consider a coloring of a graph such that each vertex is assigned a fraction of each color, with the total amount of colors at each vertex summing to $1$. We define the fractional defect of a vertex $v$ to be the sum of the overlaps with…

Combinatorics · Mathematics 2019-11-11 Wayne Goddard , Honghai Xu

The distinguishing chromatic number of a graph $G$ is the smallest number of colors needed to properly color the vertices of $G$ so that the trivial automorphism is the only symmetry of $G$ that preserves the coloring. We investigate the…

Combinatorics · Mathematics 2023-03-27 Michael D. Barrus , Jean Guillaume , Benjamin Lantz

A coloring of a graph is an assignment of colors to its vertices such that adjacent vertices have different colors. Two colorings are equivalent if they induce the same partition of the vertex set into color classes. Let $\mathcal{A}(G)$ be…

Combinatorics · Mathematics 2024-03-11 Alain Hertz , Hadrien Mélot , Sébastien Bonte , Gauvain Devillez , Pierre Hauweele

Motivated by the definition of linear coloring on simplicial complexes, recently introduced in the context of algebraic topology \cite{Civan}, and the framework through which it was studied, we introduce the linear coloring on graphs. We…

Discrete Mathematics · Computer Science 2008-07-29 Kyriaki Ioannidou , Stavros D. Nikolopoulos

The Weisfeiler-Leman (WL) algorithm is a combinatorial procedure that computes colorings on graphs, which can often be used to detect their (non-)isomorphism. Particularly the 1- and 2-dimensional versions 1-WL and 2-WL have received much…

Discrete Mathematics · Computer Science 2022-06-22 Sandra Kiefer , Daniel Neuen

We investigate proper $(a:b)$-fractional colorings of $n$-uniform hypergraphs, which generalize traditional integer colorings of graphs. Each vertex is assigned $b$ distinct colors from a set of $a$ colors, and an edge is properly colored…

Combinatorics · Mathematics 2025-04-18 Margarita Akhmejanova , Sean Longbrake

We exactly evaluate the entanglement of a six vertex and a nine vertex graph states which correspond to non ''two-colorable'' graphs. The upper bound of entanglement for five vertices ring graph state is improved to 2.9275, less than upper…

Quantum Physics · Physics 2009-09-10 Xiao-yu Chen , Li-zhen Jiang

We study the problem of approximately counting the number of list packings of a graph. The analogous problem for usual vertex coloring and list coloring has attracted a lot of attention. For list packing the setup is similar but we seek a…

Combinatorics · Mathematics 2024-02-07 Evan Camrud , Ewan Davies , Alex Karduna , Holden Lee

The star chromatic number on a graph is the minimum number of colors in a proper vertex coloring forbidding any $P_4$ with two colors (bicolored). This problem was introduced by Gr\"unbaum (1973) together with the acyclic coloring of…

Combinatorics · Mathematics 2026-03-24 Derman Keskinkilic , Lale Ozkahya

Hoffman's bound is a well-known eigenvalue bound on the chromatic number of a graph. By interpreting this bound as a parameter, we show multiple applications of colorings attaining the bound (Hoffman colorings) for several notions of graph…

Combinatorics · Mathematics 2025-08-27 Aida Abiad , Bart De Bruyn , Thijs van Veluw

A $k$-coloring of a tournament is a partition of its vertices into $k$ acyclic sets. Deciding if a tournament is 2-colorable is NP-hard. A natural problem, akin to that of coloring a 3-colorable graph with few colors, is to color a…

Data Structures and Algorithms · Computer Science 2024-11-25 Felix Klingelhoefer , Alantha Newman

We investigate the relationship between two kinds of vertex colorings of graphs: unique-maximum colorings and conflict-free colorings. In a unique-maximum coloring, the colors are ordered, and in every path of the graph the maximum color…

Discrete Mathematics · Computer Science 2009-12-17 Panagiotis Cheilaris , Geza Toth
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