Approximation and Online Algorithms: 6th International Workshop, WAOA 2008, Karlsruhe, Germany, September 18-19, 2008. Revised Papers

302 Pages·2009·3.33 MB·English

by  Jochen Könemann

Lecture Notes in Computer Science 5426
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CarnegieMellonUniversity,Pittsburgh,PA,USA
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UniversityofSurrey,Guildford,UK
JonM.Kleinberg
CornellUniversity,Ithaca,NY,USA
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UniversityofCalifornia,Berkeley,CA,USA
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Max-PlanckInstituteofComputerScience,Saarbruecken,Germany
Evripidis Bampis Martin Skutella (Eds.)
Approximation and
Online Algorithms
6th International Workshop, WAOA 2008
Karlsruhe, Germany, September 18-19, 2008
Revised Papers
1 3
VolumeEditors
EvripidisBampis
IBISC,CNRSFRE3190,Universitéd’EvryVald’Essonne
BoulevardFrançoisMitterand,91025EvryCedex,France
E-mail:[email protected]
MartinSkutella
TechnischeUniversitätBerlin
FakultätII-MathematikundNaturwissenschaften
Straßedes17.Juni136,10623Berlin,Germany
E-mail:[email protected]
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Preface
The 6th Workshop on Approximation and Online Algorithms (WAOA 2008)
focused on the design and analysis of algorithms for online and computation-
ally hard problems. Both kinds of problems have a large number of applica-
tions from a variety of fields. WAOA 2008 took place in Karlsruhe, Germany,
during September 18–19, 2008. The workshop was part of the ALGO 2008
event that also hosted ESA 2008, WABI 2008, and ATMOS 2008. The previ-
ous WAOA workshops were held in Budapest (2003), Rome (2004), Palma de
Mallorca (2005), Zurich (2006), and Eilat (2007). The proceedings of these pre-
viousWAOAworkshopsappearedasLNCSvolumes2909,3351,3879,4368,and
4927, respectively.
Topics of interest for WAOA 2008 were: algorithmic game theory, approxi-
mation classes, coloring and partitioning, competitive analysis, computational
finance, cuts and connectivity, geometric problems, inapproximability results,
mechanism design, network design, packing and covering, paradigms for design
andanalysisofapproximationandonlinealgorithms,randomizationtechniques,
real-worldapplications,and scheduling problems.In response to the call for pa-
pers,wereceived56submissions.Eachsubmissionwasreviewedbyatleastthree
referees, and the vast majority by at least four referees. The submissions were
mainlyjudgedonoriginality,technicalquality,andrelevancetothetopicsofthe
conference. Based on the reviews, the ProgramCommittee selected 22 papers.
We are grateful to Andrei Voronkov for providing the EasyChair conference
system,whichwasusedtomanagetheelectronicsubmissions,thereviewprocess,
and the electronic PC meeting. It made our task much easier.
We wouldalsoliketo thank allthe authorswho submitted papersto WAOA
2008 as well as the local organizers of ALGO 2008.
November 2008 Evripidis Bampis
Martin Skutella
Organization
Program Co-chairs
Evripidis Bampis University of Evry
Martin Skutella TU Berlin
Program Committee
Yossi Azar Microsoft Research and Tel-Aviv University
Philippe Baptiste CNRS, Ecole Polytechnique
Thomas Erlebach University of Leicester
Klaus Jansen University of Kiel
Christos Kaklamanis University of Patras
Amit Kumar IIT Delhi
Stefano Leonardi Sapienza University of Rome
Aris Pagourtzis National Technical University of Athens
Paolo Penna University of Salerno
Roberto Solis-Oba University of Western Ontario
Maxim Sviridenko IBM T. J. Watson Research Center
Marc Uetz University of Twente
Referees
Christoph Ambu¨hl Marek Chrobak Alexander Grigoriev
Aris Anagnostopoulos Miriam Di Ianni Birgit Heydenreich
Eric Angel Ilias Diakonikolas Johann Hurink
Spyridon Florian Diedrich Sandy Irani
Antonakopoulos Daniel Dressler Vincent Jost
Arash Asadpour Christoph Du¨rr Panagiotis
Vincenzo Auletta Tomas Ebenlendr Kanellopoulos
Amitabha Bagchi Khaled Elbassioni Georgia Kaouri
Evangelos Bampas Matthias Englert Hans Kellerer
Nikhil Bansal Leah Epstein Alex Kesselman
Luca Becchetti Bruno Escoffier Rohit Khandekar
Boaz Ben-Moshe William Evans Tracy Kimbrel
Andre Berger Eyal Even-Dar Stavros Kolliopoulos
Benjamin Birnbaum Esteban Feuerstein Alexander Kononov
Vincenzo Bonifaci Dimitris Fotakis Annamaria Kovacs
Ioannis Caragiannis Iftah Gamzu Christian Laforest
Panagiotis Cheilaris Fabrizio Grandoni Michael Lampis
VIII Organization
Lap Chi Lau Britta Peis Alexander Souza
Retsef Levi George Pierrakos David Steurer
Konstantin Makarychev Katerina Potika Nicola´s Stier Moses
Yury Makarychev David Pritchard Orestis Telelis
Euripides Markou Ann Robert Kavitha Telikepalli
Nicole Megow Thomas Roeblitz Aristeidis Tentes
Ioannis Milis Heiko Roeglin Ralf Th¨ole
Joe Mitchell Adi Rosen Carmine Ventre
Jerome Monnot Gianluca Rossi Anastasios Viglas
Luca Moscardelli George Rouskas Tjark Vredeveld
Rudolf Mu¨ller Stefan Schmid Matthias Westermann
Vishnawath Nagarajan Christiane Schmidt Andreas Wiese
Alantha Newman Andreas S. Schulz Gerhard Woeginger
Christos Nomikos Ulrich Schwarz Alexander Wolff
Arindam Pal Jay Sethuraman Prudence W. H. Wong
Evi Papaioannou Jiri Sgall Guochuan Zhang
Vangelis Paschos Riccardo Silvestri Vassilis Zissimopoulos
Fanny Pascual Mohit Singh
Jacob Jan Paulus Rene Sitters
Table of Contents
WAOA 2008
Max-Weight Integral Multicommodity Flow in Spiders and
High-Capacity Trees.............................................. 1
Jochen Ko¨nemann, Ojas Parekh, and David Pritchard
Size Versus Stability in the Marriage Problem ....................... 15
P´eter Biro´, David F. Manlove, and Shubham Mittal
Degree-Constrained Subgraph Problems: Hardness and Approximation
Results ......................................................... 29
Omid Amini, David Peleg, St´ephane P´erennes, Ignasi Sau, and
Saket Saurabh
A Lower Bound for Scheduling of Unit Jobs with Immediate Decision
on Parallel Machines ............................................. 43
Toma´ˇs Ebenlendr and Jiˇr´ı Sgall
Improved Randomized Online Scheduling of Unit Length Intervals and
Jobs............................................................ 53
Stanley P.Y. Fung, Chung Keung Poon, and Feifeng Zheng
Minimizing Average Flow Time on Unrelated Machines ............... 67
Ren´e A. Sitters
Cooperation in Multiorganization Matching ......................... 78
Laurent Gourv`es, J´eroˆme Monnot, and Fanny Pascual
Randomized Algorithms for Buffer Management with 2-Bounded
Delay........................................................... 92
Marcin Bienkowski, Marek Chrobak, and L(cid:2) ukasz Jez˙
A General Scheme for Designing Monotone Algorithms for Scheduling
Problems with Precedence Constraints.............................. 105
Clemens Thielen and Sven O. Krumke
Malicious BayesianCongestion Games ............................. 119
Martin Gairing
Stackelberg Strategies and Collusion in Network Games with Splittable
Flow ........................................................... 133
Tobias Harks
Peak Shaving through Resource Buffering .......................... 147
Amotz Bar-Noy, Matthew P. Johnson, and Ou Liu
X Table of Contents
On LagrangianRelaxation and Subset Selection Problems............. 160
Ariel Kulik and Hadas Shachnai
Approximation Algorithms for Prize-Collecting Network Design
Problems with General Connectivity Requirements ................... 174
Chandrashekhar Nagarajan, Yogeshwer Sharma, and
David P. Williamson
Caching Content under Digital Rights Management .................. 188
Leah Epstein, Amos Fiat, and Meital Levy
Reoptimization of Weighted Graph and Covering Problems............ 201
Davide Bilo`, Peter Widmayer, and Anna Zych
Smoothing Imprecise 1.5D Terrains................................. 214
Chris Gray, Maarten Lo¨ffler, and Rodrigo I. Silveira
Local PTAS for Dominating and Connected Dominating Set in
Location Aware Unit Disk Graphs ................................. 227
Andreas Wiese and Evangelos Kranakis
Dynamic Offline Conflict-Free Coloring for Unit Disks ................ 241
Joseph Wun-Tat Chan, Francis Y.L. Chin, Xiangyu Hong, and
Hing Fung Ting
Experimental Analysis of Scheduling Algorithms for Aggregated
Links........................................................... 253
Wojciech Jawor, Marek Chrobak, and Mart Molle
A (2−clogn) Approximation Algorithm for the Minimum Maximal
n
Matching Problem ............................................... 267
Zvi Gotthilf, Moshe Lewenstein, and Elad Rainshmidt
On the Maximum Edge Coloring Problem........................... 279
Giorgio Lucarelli, Ioannis Milis, and Vangelis Th. Paschos
Author Index.................................................. 293
Max-Weight Integral Multicommodity Flow in
Spiders and High-Capacity Trees
Jochen Ko¨nemann1, Ojas Parekh2, and David Pritchard1
1 Universityof Waterloo
Dept.of Combinatorics & Optimization, 200 UniversityAvenueWest,
Waterloo, Ontario, Canada, N2L 3G1. Fax: [phone]
[email protected], [email protected]
2 Emory University
Math/CS Department,400 Dowman Dr., Suite401,
Atlanta, GA,USA,30322. Fax: [phone]
[email protected]
Abstract. We consider the max-weight integral multicommodity flow
problem in trees. In this problem we are given an edge-capacitated tree
andweightedpairsofterminals,andtheobjectiveistofindamax-weight
integralflowbetweenterminalpairssubjecttothecapacities.Thisprob-
lemwasshowntobeAPX-hardbyGarg,VaziraniandYannakakis[Algo-
rithmica, 1997], and a 4-approximation was given by Chekuri, Mydlarz
and Shepherd [ACM Trans. Alg., 2007]. Some special cases are known
tobeexactlysolvableinpolynomialtime,includingwhenthegraphisa
path or a star.
First, when every edge has capacity at least μ ≥ 2, we use iterated
LP relaxation to obtain an improved approximation ratio of min{3,1+
4/μ+6/(μ2 −μ)}. We show this ratio bounds the integrality gap of
the natural LP relaxation. A complementary hardness result yields a
1+Θ(1/μ) thresholdofapproximability(ifP(cid:3)=NP).Second,weextend
therange of instances for which exact solutions can befound efficiently.
Whenthetreeisaspider (i.e.ifonlyonevertexhasdegreegreaterthan
2) we give a polynomial-time algorithm to find an optimal solution, as
wellasapolyhedraldescription oftheconvexhullofallintegralfeasible
solutions.
1 Introduction
Inthemax-weightintegralmulticommodityflowproblem(WMCF),wearegiven
anundirectedsupply graphG=(V,E),terminalpairs(s ,t ),...,(s ,t )where
1 1 k k
s ,t ∈ V, non-negative weights w ,...,w , and non-negative integral edge-
i i 1 k
capacities ce for all e ∈ E. The goal is to simultaneously route integr(cid:2)al si-ti
flows ofvalue y subject to the capacities,so as to maximize the weight w y .
i i i
The single-commodityversion(k =1)ofWMCFis well-knownto be solvable
in polynomial time. If we drop the integrality restriction the problem can be
solved in polynomial time via linear programming for any k. However, when
integrality is required, even the 2-commodity unit-capacity, unit-weight version
E.BampisandM.Skutella(Eds.):WAOA2008,LNCS5426,pp.1–14,2009.
(cid:2)c Springer-VerlagBerlinHeidelberg2009