DC Field | Value | Language |
---|---|---|
dc.contributor.author | Oum, Sang-il | ko |
dc.contributor.author | Seymour, P | ko |
dc.date.accessioned | 2013-03-07T12:44:09Z | - |
dc.date.available | 2013-03-07T12:44:09Z | - |
dc.date.created | 2012-02-06 | - |
dc.date.created | 2012-02-06 | - |
dc.date.issued | 2006-07 | - |
dc.identifier.citation | JOURNAL OF COMBINATORIAL THEORY SERIES B, v.96, no.4, pp.514 - 528 | - |
dc.identifier.issn | 0095-8956 | - |
dc.identifier.uri | http://hdl.handle.net/10203/90201 | - |
dc.description.abstract | We construct a polynomial-time algorithm to approximate the branch-width of certain symmetric submodular functions, and give two applications. The first is to graph "clique-width." Clique-width is a measure of the difficulty of decomposing a graph in a kind of tree-structure, and if a graph has clique-width at most k then the corresponding decomposition of the graph is called a "k-expression." We find (for fixed k) an O(n(9) log n)-time algorithm that, with input an n-vertex graph, outputs either a (2(3k+2)-1)-expression for the graph, or a witness that the graph has clique-width at least k+1. (The best earlier algorithm, by Johansson [O. Johansson, log n-approximative NLCk-decomposition in O(n(2k+1)) time (extended abstract), in: Graph-Theoretic Concepts in Computer Science, Boltenhagen, 2001, in: Lecture Notes in Comput. Sci., vol. 2204, Springer, Berlin, 2001, pp. 229-240], constructs a 2k log n-expression for graphs of clique-width at most k.) It was already known that several graph problems, NP-hard on general graphs, are solvable in polynomial time if the input graph comes equipped with a k-expression (for fixed k). As a consequence of our algorithm, the same conclusion follows under the weaker hypothesis that the input graph has clique-width at most k (thus, we no longer need to be provided with an explicit k-expression). Another application is to the area of matroid branch-width. For fixed k, we find an O(n(3.5))-time algorithm that, with input an n-element matroid in terms of its rank oracle, either outputs a branch-decomposition of width at most 3k-1 or a witness that the matroid has branch-width at least k+1. The previous algorithm by Hlineny [P. Hlineny, A parametrized algorithm for matroid branch-width, SIAM J. Comput. 35 (2) (2005) 259-277] works only for matroids represented over a finite field. (C) 2005 Elsevier Inc. All rights reserved. | - |
dc.language | English | - |
dc.publisher | ACADEMIC PRESS INC ELSEVIER SCIENCE | - |
dc.subject | GRAPHS | - |
dc.subject | ALGORITHM | - |
dc.subject | DECOMPOSITION | - |
dc.subject | RECOGNITION | - |
dc.subject | BOUNDS | - |
dc.title | Approximating clique-width and branch-width | - |
dc.type | Article | - |
dc.identifier.wosid | 000238399000007 | - |
dc.identifier.scopusid | 2-s2.0-32544455938 | - |
dc.type.rims | ART | - |
dc.citation.volume | 96 | - |
dc.citation.issue | 4 | - |
dc.citation.beginningpage | 514 | - |
dc.citation.endingpage | 528 | - |
dc.citation.publicationname | JOURNAL OF COMBINATORIAL THEORY SERIES B | - |
dc.identifier.doi | 10.1016/j.jctb.2005.10.006 | - |
dc.contributor.localauthor | Oum, Sang-il | - |
dc.contributor.nonIdAuthor | Seymour, P | - |
dc.type.journalArticle | Article | - |
dc.subject.keywordAuthor | clique-width | - |
dc.subject.keywordAuthor | branch-width | - |
dc.subject.keywordAuthor | rank-width | - |
dc.subject.keywordAuthor | submodular functions | - |
dc.subject.keywordAuthor | matroid | - |
dc.subject.keywordPlus | GRAPHS | - |
dc.subject.keywordPlus | ALGORITHM | - |
dc.subject.keywordPlus | DECOMPOSITION | - |
dc.subject.keywordPlus | RECOGNITION | - |
dc.subject.keywordPlus | BOUNDS | - |
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