Rights / licenseIn Copyright - Non-Commercial Use Permitted
In the valley-free path model, a path in a given directed graph is valid if it consists of a sequence of forward edges followed by a sequence of backward edges. This model is moti vated by routing policies of autonomous systems in the Internet. We give a 2-approximation algorithm for the problem of computing a maximum number of edge- or vertex-disjoint valid paths between two given vertices s and t, and we show that no better approximation ra tio is possible unless P = NP. Furthermore, we give a 2-approximation for the problem of computing a minimum vertex cut that separates s and t with respect to all valid paths and prove that the problem is APX-hard. The corresponding problem for edge cuts is shown to be polynomial-time solvable. We present additional results for acyclic graphs. Show more
Journal / seriesTIK Report
PublisherETH Zurich, Computer Engineering and Networks Laboratory
Edition / versionVersion 1
Organisational unit02640 - Inst. f. Technische Informatik und Komm. / Computer Eng. and Networks Lab.
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