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oai:drops-oai.dagstuhl.de:4448 2024-03-06T10:35:02Z ddc:004 open_access

Weighted Coloring in Trees Araujo, Julio Nisse, Nicolas Pérennes, Stéphane Weighted Coloring Max Coloring Exponential Time Hypothesis 3-SAT A proper coloring of a graph is a partition of its vertex set into stable sets, where each part corresponds to a color. For a vertex-weighted graph, the weight of a color is the maximum weight of its vertices. The weight of a coloring is the sum of the weights of its colors. Guan and Zhu (1997) defined the weighted chromatic number of a vertex-weighted graph G as the smallest weight of a proper coloring of G. If vertices of a graph have weight 1, its weighted chromatic number coincides with its chromatic number. Thus, the problem of computing the weighted chromatic number, a.k.a. Max Coloring Problem, is NP-hard in general graphs. It remains NP-hard in some graph classes as bipartite graphs. Approximation algorithms have been designed in several graph classes, in particular, there exists a PTAS for trees. Surprisingly, the time-complexity of computing this parameter in trees is still open. The Exponential Time Hypothesis (ETH) states that 3-SAT cannot be solved in sub-exponential time. We show that, assuming ETH, the best algorithm to compute the weighted chromatic number of n-node trees has time-complexity n O(log(n)). Our result mainly relies on proving that, when computing an optimal proper weighted coloring of a graph G, it is hard to combine colorings of its connected components. Schloss Dagstuhl – Leibniz-Zentrum für Informatik Julio Araujo and Nicolas Nisse and Stéphane Pérennes 2014 Is Part Of LIPIcs, Volume 25, 31st International Symposium on Theoretical Aspects of Computer Science (STACS 2014) InProceedings Text doc-type:ResearchArticle publishedVersion application/pdf doi:10.4230/LIPIcs.STACS.2014.75 urn:nbn:de:0030-drops-44484 https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2014.75 eng https://creativecommons.org/licenses/by/3.0/legalcode