Approximating multiroot 3-outconnected subgraphs

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The multiroot k-outconnected subgraph problem is: given an undirected graph G with nonnegative costs on the edges, a vector of q root nodes R = (r1, ..., rq), and a vector K = (k1, ..., kq) of connectivity requirements (with k = max ki), find a minimum-cost K-outconnected from R spanning subgraph (that is, for every i = 1, ..., q there are ki internally vertex disjoint paths from ri to any other node). The best known algorithm for this problem has approximation ratio 2q, where q can be as large as k-1. For no value of k≥2 a better approximation algorithm is known. We consider the case ki∈{1, 2, 3} which may arise in practical networks. For this case we give a 10/3 -approximation algorithm, improving the best previously known 4-approximation. Our algorithm also implies an improvement for arbitrary k. In the case we have an initial graph which is 2-connected, our algorithm achieves approximation ratio 2.

Original languageEnglish
StatePublished - 1999
Externally publishedYes
EventProceedings of the 1999 10th Annual ACM-SIAM Symposium on Discrete Algorithms - Baltimore, MD, USA
Duration: 17 Jan 199919 Jan 1999


ConferenceProceedings of the 1999 10th Annual ACM-SIAM Symposium on Discrete Algorithms
CityBaltimore, MD, USA


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