10.4230/LIPICS.STACS.2011.129
Kolman, Petr
Petr
Kolman
Scheideler, Christian
Christian
Scheideler
Towards Duality of Multicommodity Multiroute Cuts and Flows: Multilevel Ball-Growing
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
2011
Article
Multicommodity flow
Multiroute flow
Cuts
Duality
Schwentick, Thomas
Thomas
Schwentick
Dürr, Christoph
Christoph
Dürr
2011
2011-03-11
2011-03-11
2011-03-11
en
urn:nbn:de:0030-drops-30051
10.4230/LIPIcs.STACS.2011
978-3-939897-25-5
1868-8969
10.4230/LIPIcs.STACS.2011
LIPIcs, Volume 9, STACS 2011
28th International Symposium on Theoretical Aspects of Computer Science (STACS 2011)
2013
9
11
129
140
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Schwentick, Thomas
Thomas
Schwentick
Dürr, Christoph
Christoph
Dürr
1868-8969
Leibniz International Proceedings in Informatics (LIPIcs)
2011
9
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
12 pages
644564 bytes
application/pdf
Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported license
info:eu-repo/semantics/openAccess
An elementary h-route flow, for an integer h >= 1, is a set of h edge-disjoint paths between a source and a sink, each path carrying a unit of flow, and an h-route flow is a non-negative linear combination of elementary h-route flows. An h-route cut is a set of edges whose removal decreases the maximum h-route flow between a given source-sink pair (or between every source-sink pair in the multicommodity setting) to zero. The main result of this paper is an approximate duality theorem for multicommodity
$h$-route cuts and flows, for h <= 3: The size of a minimum h-route cut is at least f/h and at most O(log^3(k)f) where f is the size of the maximum h-route flow and k is the number of commodities. The main step towards the proof of this duality is the design and analysis of a polynomial-time approximation algorithm for the minimum h-route cut problem for h=3 that has an approximation ratio of O(log^3 k). Previously, polylogarithmic approximation was known only for $h$-route cuts for h <= 2.
A key ingredient of our algorithm is a novel rounding technique that we call multilevel ball-growing. Though the proof of the duality relies on this algorithm, it is not a straightforward corollary of it as in the case of classical multicommodity flows and cuts. Similar results are shown also for the sparsest multiroute cut problem.
LIPIcs, Vol. 9, 28th International Symposium on Theoretical Aspects of Computer Science (STACS 2011), pages 129-140