Integer Programming and Combinatorial Optimization
Volume 1610 of the series Lecture Notes in Computer Science pp 99113
Improved Approximation Algorithms for Capacitated Facility Location Problems
 Fabián A. ChudakAffiliated withIBM T.J. Watson Research Center
 , David P. WilliamsonAffiliated withIBM T.J. Watson Research Center
Abstract
In a recent surprising result, Korupolu, Plaxton, and Rajaraman [10,11] showed that a simple local search heuristic for the capacitated facility location problem (CFLP) in which the service costs obey the triangle inequality produces a solution in polynomial time which is within a factor of 8 + ε of the value of an optimal solution. By simplifying their analysis, we are able to show that the same heuristic produces a solution which is within a factor of 6(1 + ε) of the value of an optimal solution. Our simplified analysis uses the supermodularity of the cost function of the problem and the integrality of the transshipment polyhedron.
Additionally, we consider the variant of the CFLP in which one may open multiple copies of any facility. Using ideas from the analysis of the local search heuristic, we show how to turn any αapproximation algorithm for this variant into one which, at an additional cost of twice the optimum of the standard CFLP, opens at most one additional copy of any facility. This allows us to transform a recent 3approximation algorithm of Chudak and Shmoys [5] that opens many additional copies of facilities into a polynomialtime algorithm which only opens one additional copy and has cost no more than five times the value of the standard CFLP.
 Title
 Improved Approximation Algorithms for Capacitated Facility Location Problems
 Book Title
 Integer Programming and Combinatorial Optimization
 Book Subtitle
 7th International IPCO Conference Graz, Austria, June 9–11, 1999 Proceedings
 Pages
 pp 99113
 Copyright
 1999
 DOI
 10.1007/3540487778_8
 Print ISBN
 9783540660194
 Online ISBN
 9783540487777
 Series Title
 Lecture Notes in Computer Science
 Series Volume
 1610
 Series ISSN
 03029743
 Publisher
 Springer Berlin Heidelberg
 Copyright Holder
 SpringerVerlag Berlin Heidelberg
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 Editors

 Gérard Cornuéjols ^{(4)}
 Rainer E. Burkard ^{(5)}
 Gerhard J. Woeginger ^{(5)}
 Editor Affiliations

 4. GSIA, Carnegie Mellon University
 5. Institut für Mathematik, Technische Universität Graz
 Authors

 Fabián A. Chudak ^{(6)}
 David P. Williamson ^{(7)}
 Author Affiliations

 6. IBM T.J. Watson Research Center, Room 36241, P.O. Box 218, Yorktown Heights, NY, 10598
 7. IBM T.J. Watson Research Center, Room 33219, P.O. Box 218, Yorktown Heights, NY, 10598
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