Displaying similar documents to “Graph Radiocoloring Concepts”

Solutions of Some L(2, 1)-Coloring Related Open Problems

Nibedita Mandal, Pratima Panigrahi (2016)

Discussiones Mathematicae Graph Theory

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An L(2, 1)-coloring (or labeling) of a graph G is a vertex coloring f : V (G) → Z+ ∪ {0} such that |f(u) − f(v)| ≥ 2 for all edges uv of G, and |f(u)−f(v)| ≥ 1 if d(u, v) = 2, where d(u, v) is the distance between vertices u and v in G. The span of an L(2, 1)-coloring is the maximum color (or label) assigned by it. The span of a graph G is the smallest integer λ such that there exists an L(2, 1)-coloring of G with span λ. An L(2, 1)-coloring of a graph with span equal to the span of...

2-Tone Colorings in Graph Products

Jennifer Loe, Danielle Middelbrooks, Ashley Morris, Kirsti Wash (2015)

Discussiones Mathematicae Graph Theory

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A variation of graph coloring known as a t-tone k-coloring assigns a set of t colors to each vertex of a graph from the set {1, . . . , k}, where the sets of colors assigned to any two vertices distance d apart share fewer than d colors in common. The minimum integer k such that a graph G has a t- tone k-coloring is known as the t-tone chromatic number. We study the 2-tone chromatic number in three different graph products. In particular, given graphs G and H, we bound the 2-tone chromatic...

The cost chromatic number and hypergraph parameters

Gábor Bacsó, Zsolt Tuza (2006)

Discussiones Mathematicae Graph Theory

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In a graph, by definition, the weight of a (proper) coloring with positive integers is the sum of the colors. The chromatic sum is the minimum weight, taken over all the proper colorings. The minimum number of colors in a coloring of minimum weight is the cost chromatic number or strength of the graph. We derive general upper bounds for the strength, in terms of a new parameter of representations by edge intersections of hypergraphs.

On the proper intervalization of colored caterpillar trees

Carme Àlvarez, Maria Serna (2009)

RAIRO - Theoretical Informatics and Applications

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This paper studies the computational complexity of the problem (), when the input graph is a colored caterpillar, parameterized by hair length. In order prove our result we establish a close relationship between the and a graph layout problem the (). We show a dichotomy: the and the are NP-complete for colored caterpillars of hair length 2, while both problems are in P for colored caterpillars of hair length 2. For the hardness results we provide a reduction from the , while the...

Semi-definite positive programming relaxations for graph K 𝐧 -coloring in frequency assignment

Philippe Meurdesoif, Benoît Rottembourg (2001)

RAIRO - Operations Research - Recherche Opérationnelle

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In this paper we will describe a new class of coloring problems, arising from military frequency assignment, where we want to minimize the number of distinct n -uples of colors used to color a given set of n -complete-subgraphs of a graph. We will propose two relaxations based on Semi-Definite Programming models for graph and hypergraph coloring, to approximate those (generally) NP-hard problems, as well as a generalization of the works of Karger et al. for hypergraph coloring, to find...

Coloring subgraphs with restricted amounts of hues

Wayne Goddard, Robert Melville (2017)

Open Mathematics

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We consider vertex colorings where the number of colors given to specified subgraphs is restricted. In particular, given some fixed graph F and some fixed set A of positive integers, we consider (not necessarily proper) colorings of the vertices of a graph G such that, for every copy of F in G, the number of colors it receives is in A. This generalizes proper colorings, defective coloring, and no-rainbow coloring, inter alia. In this paper we focus on the case that A is a singleton set....

On-line 𝓟-coloring of graphs

Piotr Borowiecki (2006)

Discussiones Mathematicae Graph Theory

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For a given induced hereditary property 𝓟, a 𝓟-coloring of a graph G is an assignment of one color to each vertex such that the subgraphs induced by each of the color classes have property 𝓟. We consider the effectiveness of on-line 𝓟-coloring algorithms and give the generalizations and extensions of selected results known for on-line proper coloring algorithms. We prove a linear lower bound for the performance guarantee function of any stingy on-line 𝓟-coloring algorithm. In the...