van den Heuvel, J. and Johnson, M. (2008) 'Transversals of subtree hypergraphs and the source location problem in digraphs.', Networks., 51 (2). pp. 113-119.
A hypergraph H = (V,E) is a subtree hypergraph if there is a tree T on V such that each hyperedge of E induces a subtree of T. Since the number of edges of a subtree hypergraph can be exponential in n = |V|, one can not always expect to be able to find a minimum size transversal in time polynomial in n. In this paper, we show that if it is possible to decide if a set of vertices W ⊆ V is a transversal in time S(n) (where n = |V|), then it is possible to find a minimum size transversal in O(n3S(n)). This result provides a polynomial algorithm for the Source Location Problem: a set of (k,l)-sources for a digraph D = (V,A) is a subset S of V such that for any v ∈ V there are k arc-disjoint paths that each join a vertex of S to v and l arc-disjoint paths that each join v to S. The Source Location Problem is to find a minimum size set of (k,l)-sources. We show that this is a case of finding a transversal of a subtree hypergraph, and that in this case S(n) is polynomial.
|Keywords:||Graphs, Hypergraphs, Source location, Algorithms.|
|Full text:||(AM) Accepted Manuscript|
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|Publisher Web site:||http://dx.doi.org/10.1002/net.20206|
|Publisher statement:||This is the accepted version of the following article: van den Heuvel, J. and Johnson, M. (2008), Transversals of subtree hypergraphs and the source location problem in digraphs. Networks, 51(2): 113-119, which has been published in final form at http://dx.doi.org/10.1002/net.20206. This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.|
|Record Created:||07 Oct 2008|
|Last Modified:||11 Dec 2015 11:23|
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