Fractional Path Coloring in Bounded Degree Trees with Applications

I. Caragiannis 1 Afonso Ferreira 2 C. Kaklamanis 1 Stéphane Pérennes 2 Hervé Rivano 2
2 MASCOTTE - Algorithms, simulation, combinatorics and optimization for telecommunications
CRISAM - Inria Sophia Antipolis - Méditerranée , COMRED - COMmunications, Réseaux, systèmes Embarqués et Distribués
Abstract : This paper studies the natural linear programming relaxation of the path coloring problem. We prove constructively that finding an optimal fractional path coloring is Fixed Parameter Tractable (FPT), with the degree of the tree as parameter: the fractional coloring of paths in a bounded degree trees can be done in a time which is linear in the size of the tree, quadratic in the load of the set of paths, while exponential in the degree of the tree. We give an algorithm based on the generation of an efficient polynomial size linear program. Our algorithm is able to explore in polynomial time the exponential number of different fractional colorings, thanks to the notion of trace of a coloring that we introduce. We further give an upper bound on the cost of such a coloring in binary trees and extend this algorithm to bounded degree graphs with bounded treewidth. Finally, we also show some relationships between the integral and fractional problems, and derive a (1 + 5/3e) ~= 1.61 approximation algorithm for the path coloring problem in bounded degree trees, improving on existing results. This classic combinatorial problem finds applications in the minimization of the number of wavelengths in wavelength division multiplexing (WDM) optical networks.
Type de document :
Article dans une revue
Algorithmica, Springer Verlag, 2010, 58 (2), pp.516-540. <10.1007/s00453-009-9278-3>
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Contributeur : Hervé Rivano <>
Soumis le : jeudi 26 mars 2009 - 13:10:30
Dernière modification le : lundi 15 novembre 2010 - 15:03:26
Document(s) archivé(s) le : vendredi 12 octobre 2012 - 14:25:08


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I. Caragiannis, Afonso Ferreira, C. Kaklamanis, Stéphane Pérennes, Hervé Rivano. Fractional Path Coloring in Bounded Degree Trees with Applications. Algorithmica, Springer Verlag, 2010, 58 (2), pp.516-540. <10.1007/s00453-009-9278-3>. <hal-00371052>



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