Displaying similar documents to “New lower bounds on the weighted chromatic number of a graph”

Branch-and-bound algorithm for total weighted tardiness minimization on parallel machines under release dates assumptions

Imed Kacem, Nizar Souayah, Mohamed Haouari (2012)

RAIRO - Operations Research

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This paper deals with the parallel-machine scheduling problem with the aim of minimizing the total (weighted) tardiness under the assumption of different release dates. This problem has been proven to be NP-hard. We introduce some new lower and upper bounds based on different approaches. We propose a branch-and-bound algorithm to solve the weighted and unweighted total tardiness. Computational experiments were performed on a large set of ...

Branch-and-bound algorithm for total weighted tardiness minimization on parallel machines under release dates assumptions

Imed Kacem, Nizar Souayah, Mohamed Haouari (2012)

RAIRO - Operations Research

Similarity:

This paper deals with the parallel-machine scheduling problem with the aim of minimizing the total (weighted) tardiness under the assumption of different release dates. This problem has been proven to be NP-hard. We introduce some new lower and upper bounds based on different approaches. We propose a branch-and-bound algorithm to solve the weighted and unweighted total tardiness. Computational experiments were performed on a large set of ...

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.

Relations between the domination parameters and the chromatic index of a graph

Włodzimierz Ulatowski (2009)

Discussiones Mathematicae Graph Theory

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In this paper we show upper bounds for the sum and the product of the lower domination parameters and the chromatic index of a graph. We also present some families of graphs for which these upper bounds are achieved. Next, we give a lower bound for the sum of the upper domination parameters and the chromatic index. This lower bound is a function of the number of vertices of a graph and a new graph parameter which is defined here. In this case we also characterize graphs for which a respective...

List coloring of complete multipartite graphs

Tomáš Vetrík (2012)

Discussiones Mathematicae Graph Theory

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The choice number of a graph G is the smallest integer k such that for every assignment of a list L(v) of k colors to each vertex v of G, there is a proper coloring of G that assigns to each vertex v a color from L(v). We present upper and lower bounds on the choice number of complete multipartite graphs with partite classes of equal sizes and complete r-partite graphs with r-1 partite classes of order two.

A σ₃ type condition for heavy cycles in weighted graphs

Shenggui Zhang, Xueliang Li, Hajo Broersma (2001)

Discussiones Mathematicae Graph Theory

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A weighted graph is a graph in which each edge e is assigned a non-negative number w(e), called the weight of e. The weight of a cycle is the sum of the weights of its edges. The weighted degree d w ( v ) of a vertex v is the sum of the weights of the edges incident with v. In this paper, we prove the following result: Suppose G is a 2-connected weighted graph which satisfies the following conditions: 1. The weighted degree sum of any three independent vertices is at least m; 2. w(xz) = w(yz)...

A weighted graph polynomial from chromatic invariants of knots

Steven D. Noble, Dominic J. A. Welsh (1999)

Annales de l'institut Fourier

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Motivated by the work of Chmutov, Duzhin and Lando on Vassiliev invariants, we define a polynomial on weighted graphs which contains as specialisations the weighted chromatic invariants but also contains many other classical invariants including the Tutte and matching polynomials. It also gives the symmetric function generalisation of the chromatic polynomial introduced by Stanley. We study its complexity and prove hardness results for very restricted classes of graphs.