Approximating the smallest k-edge connected spanning subgraph by LP-rounding

作者: Michel X. Goemans , Harold N. Gabow , Éva Tardos , David P. Williamson

DOI: 10.1002/NET.V53:4

关键词: MultigraphDiscrete mathematicsConnectivityGraph (abstract data type)MathematicsApproximation algorithmDirected graphUpper and lower boundsRound-off errorCombinatoricsRounding

摘要: The smallest k-ECSS problem is, given a graph along with an integer k, find spanning subgraph that is k-edge connected and contains the fewest possible number of edges. We examine natural approximation algorithm based on rounding LP solution. A tight bound ratio 1 + 3-k for undirected graphs k > odd, 2-k even, directed arbitrary. Using iterated improves first upper to 2-k. On hardness side we show some absolute constant c 0, any ≥ 2 (k 1), polynomial-time approximating (directed) multigraphs within c-k would imply P = NP. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009

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