Lecture Notes in Computer Science 8973Commenced Publication in 1973Founding and Former Series Editors:Gerhard Goos, Juris Hartmanis, and Jan van Leeuwen

Editorial Board

David HutchisonLancaster University, UK

Takeo KanadeCarnegie Mellon University, Pittsburgh, PA, USA

Josef KittlerUniversity of Surrey, Guildford, UK

Jon M. KleinbergCornell University, Ithaca, NY, USA

Friedemann MatternETH Zurich, Switzerland

John C. MitchellStanford University, CA, USA

Moni NaorWeizmann Institute of Science, Rehovot, Israel

C. Pandu RanganIndian Institute of Technology, Madras, India

Bernhard SteffenTU Dortmund University, Germany

Demetri TerzopoulosUniversity of California, Los Angeles, CA, USA

Doug TygarUniversity of California, Berkeley, CA, USA

Gerhard WeikumMax Planck Institute for Informatics, Saarbruecken, Germany

M. Sohel Rahman Etsuji Tomita (Eds.)

WALCOM: Algorithmsand Computation

9th International Workshop, WALCOM 2015Dhaka, Bangladesh, February 26-28, 2015Proceedings

13

Volume Editors

M. Sohel RahmanBUET, Department of CSEECE Building, West Palasi, Dhaka 1205, BangladeshE-mail: msrahman@cse.buet.ac.bd

Etsuji TomitaThe University of Electro-CommunicationsThe Advanced Algorithms Research LaboratoryChofugaoka 1-5-1, Chofu, Tokyo 182-8585, JapanE-mail: tomita@ice.uec.ac.jp

ISSN 0302-9743 e-ISSN 1611-3349ISBN 978-3-319-15611-8 e-ISBN 978-3-319-15612-5DOI 10.1007/978-3-319-15612-5Springer Cham Heidelberg New York Dordrecht London

Library of Congress Control Number: 2015930429

LNCS Sublibrary: SL 1 – Theoretical Computer Science and General Issues

© Springer International Publishing Switzerland 2015This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part ofthe material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting, reproduction on microfilms or in any other physical way, and transmission or informationstorage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodologynow known or hereafter developed. Exempted from this legal reservation are brief excerpts in connectionwith reviews or scholarly analysis or material supplied specifically for the purpose of being entered andexecuted on a computer system, for exclusive use by the purchaser of the work. Duplication of this publicationor parts thereof is permitted only under the provisions of the Copyright Law of the Publisher’s location,in ist current version, and permission for use must always be obtained from Springer. Permissions for usemay be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecutionunder the respective Copyright Law.The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoes not imply, even in the absence of a specific statement, that such names are exempt from the relevantprotective laws and regulations and therefore free for general use.While the advice and information in this book are believed to be true and accurate at the date of publication,neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors oromissions that may be made. The publisher makes no warranty, express or implied, with respect to thematerial contained herein.

Typesetting: Camera-ready by author, data conversion by Scientific Publishing Services, Chennai, India

Printed on acid-free paper

Springer is part of Springer Science+Business Media (www.springer.com)

Preface

This proceedings volume contains papers presented at WALCOM 2015, the 9thInternational Workshop on Algorithms and Computation, held during Febru-ary 26–28, 2015, at the Training Institute, Atomic Energy Research Establish-ment (AERE), Ganakbari, Savar, Dhaka, Bangladesh. The workshop covereddiverse areas of algorithms and computation, namely, approximation algorithms,data structures, computational geometry, combinatorial algorithms, distributedand online algorithms, graph drawing, graph algorithms, combinatorial prob-lems and computational complexity. The workshop was organized jointly bythe Bangladesh Atomic Energy Commission, Bangladesh Academy of Sciences(BAS), and the Department of Computer Science and Engineering, BUET.

WALCOM is an annual conference series on all aspects of algorithms andcomputation. Since its inception in 2007, it has been held as a yearly event.WALCOM has grown substantially in reputation and has been able to attractresearchers and scientists around the globe. WALCOM 2015 was organized incooperation with IEICE Technical Committee on Theoretical Foundations ofComputing (COMP) and the Special Interest Group for ALgorithms (SIGAL)of the Information Processing Society of Japan (IPSJ). This year, 88 manuscriptswere submitted to WALCOM. After a few withdrawals, 85 papers with authorsfrom 25 different countries were reviewed. Among these submissions, 26 wereaccepted as full papers and three were accepted as short papers. Papers wereselected based on a thorough reviewing (usually, at least three review reportsper paper) followed by in-depth discussion sessions by the WALCOM ProgramCommittee comprising 29 researchers of international repute from Australia,Bangladesh, Canada, France, Germany, Hong Kong, India, Italy, Japan, Korea,The Netherlands, Poland, Sweden, Switzerland, Taiwan, and USA. This year,for the first time in the history of WALCOM, Best Paper Awards were given.We are happy to highlight that “Edge-Colorings of Weighted Graphs” authoredby Yuji Obata and Takao Nishizeki and “An Almost Optimal Algorithm forVoronoi Diagrams of Non-Disjoint Line Segments” authored by Sang Won Baewere selected for the Best Paper Awards by the Program Committee. We arealso delighted to announce that following the tradition of the previous years,two special issues—one in Journal of Graph Algorithms and Applications andthe other in Journal of Discrete Algorithms—are being organized comprising theextended versions of selected papers from WALCOM 2015.

In addition to the 29 contributed talks, the scientific program of the work-shop included three invited talks by the 2006 Godel Prize winner Prof. Manin-dra Agrawal of the Indian Institute of Technology Kanpur, India, Prof. Shin-ichiMinato of Hokkaido University, Japan, and Prof. Rajeev Raman, University ofLeicester, UK. We are extremely grateful to our invited speakers for their ex-cellent talks at the workshop. We thank all the authors who submitted their

VI Preface

work for consideration to WALCOM 2015. We deeply appreciate the competentand timely handling of the submissions of all Program Committee members andexternal reviewers, despite their extremely busy schedule. In this connection wemust also acknowledge the EasyChair conference management system for provid-ing a beautiful platform for conference administration. We must thank Springeras well for publishing the proceedings of WALCOM 2015 in their prestigiousLNCS series. We are indebted to the WALCOM Steering Committee and theAdvisory Committee for their continuous guidance and support. Above all, weare extremely grateful to the Organizing Committee of WALCOM 2015 for mak-ing the event a grand success. Last but not the least, we express our heartiestgratitude to the kind and generous support of the sponsors.

February 2015 M. Sohel RahmanEtsuji Tomita

Organization

WALCOM Steering Committee

Kyung-Yong Chwa Korea Advanced Institute of Science andTechnology

Costas S. Iliopoulos King’s College London, UKM. Kaykobad Bangladesh University of Engineering &

TechnologyPetra Mutzel TU Dortmund, GermanyShin-ichi Nakano Gunma University, JapanSubhas Chandra Nandy Indian Statistical Institute, IndiaTakao Nishizeki Tohoku University, JapanC. Pandu Rangan Indian Institute of Technology, Madras, IndiaMd. Saidur Rahman Bangladesh University of Engineering &

Technology

WALCOM 2015 Organizers

WALCOM 2015 Supporters

VIII Organization

WALCOM 2015 Program Committee

Guillaume Blin Universite de Bordeaux, FranceHans L. Bodlaender Utrecht University, The NetherlandsFrancis Y.L. Chin The University of Hong Kong, Hong Kong,

SAR ChinaRezaul A. Chowdhury Stony Brook University, USANaveen Garg Indian Institute of Technology Delhi, IndiaMohammad T. Hajiaghayi University of Maryland, USASeok-Hee Hong University of Sydney, AustraliaKazuo Iwama Kyoto University, JapanMing-Yang Kao Northwestern University, USARalf Klasing CNRS, University of Bordeaux, FranceMichael Langston University of Tennessee, USAAndrzej Lingas Lund University, SwedenGiuseppe Liotta University of Perugia, ItalyIan Munro University of Waterloo, CanadaPetra Mutzel TU Dortmund, GermanySubhas Chandra Nandy Indian Statistical Institute, IndiaKunsoo Park Seoul National University, KoreaMicha�l Pilipczuk University of Warsaw, PolandM. Sohel Rahman Bangladesh University of Engineering &

Technology (BUET), Bangladesh (Co-chair)Md. Saidur Rahman Bangladesh University of Engineering &

Technology (BUET), BangladeshWojciech Rytter University of Warsaw, PolandKunihiko Sadakane The University of Tokyo, JapanSandeep Sen Indian Institute of Technology Delhi, IndiaBill Smyth McMaster University, CanadaEtsuji Tomita The University of Electro-Communications,

Japan (Co-chair)Osamu Watanabe Tokyo Institute of Technology, JapanSue Whitesides University of Victoria, CanadaPeter Widmayer ETH Zurich, SwitzerlandHsu-Chun Yen National Taiwan University, Taiwan

WALCOM 2015 Advisory Committee

Mesbahuddin Ahmad President, Bangladesh Academy of SciencesM. Shamsher Ali Fellow, Bangladesh Academy of SciencesKhawaja Muhammed

Sultanul Aziz Secretary, Bangladesh Academy of SciencesNaiyyum Choudhury Fellow, Bangladesh Academy of Sciences

Organization IX

Khaleda Ekram Vice-Chancellor, Bangladesh Universityof Engineering & Technology

Md. Monzurul Haque Member (Engineering), Bangladesh AtomicEnergy Commission

Mahmudul Hasan Member (Physical Science), BangladeshAtomic Energy Commission

Mohammad Mahfuzul Islam Head, Bangladesh Universityof Engineering & Technology

Md. Monirul Islam Chairman, BangladeshAtomic Energy Commission

M. Kaykobad Professor, Bangladesh University ofEngineering & Technology

Harun-Or-Rashid Director General, BangladeshAtomic Energy Commission

M. Ali Zulquarnain Member (Planning), Bangladesh AtomicEnergy Commission

WALCOM 2015 Organizing Committee

Md. Shakil Ahmed Bangladesh Atomic Energy Commission(Joint Secretary)

Md. Mostafa Akbar Bangladesh University of Engineering &Technology

Addris Ali Bangladesh Atomic Energy CommissionMohammed Eunus Ali Bangladesh University of Engineering &

TechnologyMd. Ashikur Rahman Azim Bangladesh University of Engineering &

TechnologyKhawaja Muhammed

Sultanul Aziz Bangladesh Academy of SciencesMohammad Al-Mahmud Bangladesh University of Engineering &

TechnologyMadhusudan Basak Bangladesh University of Engineering &

TechnologyMd. Muradul Bashir Bangladesh University of Engineering &

TechnologyNaiyyum Choudhury Bangladesh Academy of SciencesAnada Kumar Das Bangladesh Atomic Energy CommissionMohammod Abu Sayid Haque Bangladesh Atomic Energy CommissionMd. Mahbubul Hoq Bangladesh Atomic Energy CommissionMd. Dulal Hossain Bangladesh Atomic Energy CommissionMd. Iqbal Hossain Bangladesh University of Engineering &

Technology

X Organization

Md. Saddam Hossain Bangladesh University of Engineering &Technology

Alim-Al-Islam Bangladesh University of Engineering &Technology

A T M Fayezul Islam Bangladesh Atomic Energy CommissionMohammad Mahfuzul Islam Bangladesh University of Engineering &

TechnologyMd. Nurul Islam Bangladesh Atomic Energy CommissionImtiaz Kamal Bangladesh Atomic Energy CommissionMd. Rezaul Karim Dhaka University, BangladeshM. Kaykobad Bangladesh University of Engineering &

Technology (Co-chair)Shahidul Islam Khan Bangladesh University of Engineering &

TechnologyMubarak Ahmed Khan Bangladesh Atomic Energy CommissionTanvir Ahmed Khan Bangladesh University of Engineering &

TechnologyShefaly Khatun Bangladesh Atomic Energy CommissionANK Mamun Bangladesh Atomic Energy CommissionMd. Abdul Manan Bangladesh Atomic Energy CommissionM. A. Mazed Bangladesh Academy of SciencesMd. Nasrul Haque Mia Bangladesh Atomic Energy CommissionKh. Nuba Shittain Mitu Bangladesh Atomic Energy CommissionSyed Abdul Momin Bangladesh Atomic Energy CommissionMd. Karam Newaz Bangladesh Atomic Energy CommissionMd. Abdur Rahim Bangladesh Atomic Energy CommissionMd. Anisur Rahman Bangladesh Atomic Energy CommissionMd. Mizanur Rahman Bangladesh University of Engineering &

TechnologyMd. Saidur Rahman Bangladesh University of Engineering &

Technology (Co-chair)M. Sohel Rahman Bangladesh University of Engineering &

TechnologyHarun-Or-Rashid Bangladesh Atomic Energy Commission

(Co-chair)Sudipto Saha Bangladesh Atomic Energy CommissionKhaled Mahmud Shahriar Bangladesh University of Engineering &

TechnologyRifat Shahriyar Bangladesh University of Engineering &

Technology (Secretary)Sadia Sharmin Bangladesh University of Engineering &

Technology (Joint Secretary)Md. Malek Sonar Bangladesh Atomic Energy CommissionShaheena Sultana Bangladesh University of Engineering &

Technology

Organization XI

Shauli Sarmin Sumi Bangladesh Atomic Energy CommissionEtsuji Tomita The University of Electro-Communications,

JapanMd. Meshbah Uddin Bangladesh Atomic Energy CommissionMd. Shuza Uddin Bangladesh Atomic Energy CommissionSk. Md. Yunus Bangladesh Atomic Energy CommissionMd. Anzan-Uz-Zaman Bangladesh Atomic Energy Commission

WALCOM 2015 Additional Reviewers

Agarwal, PankajAspnes, JamesBacher, AxelBannai, HideoBaswana, SurenderBateni, MohammadhosseinBishnu, ArijitBrinda, KarelBockenhauer, Hans-JoachimCai, Jin-YiChitnis, RajeshCzyzowicz, Jerzyde Rugy Altherre, NicolasDehghani, SinaDevismes, StephaneDidimo, WalterDiwan, AjitDu, HaiEhsani Banafati, SoheilEsfandiari, HosseinEvans, WilliamFischer, JohannesFlocchini, PaolaFoucaud, FlorentGambette, PhilippeGanapathi, PramodGrilli, LucaGrytczuk, Jaros�lawGudmundsson, JoachimHagan, RonHarsha, PrahaladhJansson, JesperKakugawa, HirotsuguKarim, Md. Rezaul

Kortsarz, GuyKowaluk, Miros�lawKrasikov, IliaKriege, NilsKurz, DenisKutzkov, KonstantinLu, AllanManlove, DavidManne, FredrikMccauley, SamuelMitchell, JosephMondal, DebajyotiMonemizadeh, MortezaMontecchiani, FabrizioMorris, TimMomke, TobiasNakano, Shin-IchiNishat, Rahnuma IslamNomikos, ChristosNollenburg, MartinPajak, DominikPapadopoulou, EvanthiaPersson, MiaPhillips, CharlesPilipczuk, MarcinPurohit, ManishRadoszewski, JakubRoselli, VincenzoRoy, SasankaRutter, IgnazSikora, FlorianSledneu, DzmitrySmid, MichielSommer, Christian

XII Organization

Soueidan, HayssamSu, Hsin-HaoSuri, SubhashSzreder, BartoszTixeuil, Sebastien

Vialette, StephaneWang, KaiWolff, AlexanderZhang, YongZylinski, Pawe�l

WALCOM 2015 Sponsors

Invited Talks(Abstracts)

Polynomial Identity Testing

Manindra Agrawal�

1 Introduction

Polynomial Identity Testing (PIT in short) is the problem of checking if a poly-nomial of n variables with coefficients from r a field F is identically zero, i.e., ifall its terms cancel each other out. The problem is very simple to solve efficientlyif the polynomial is given in the usual sum-of-products form:

P (x1, x2, . . . , xn) =∑

0≤i1,i2,...,in≤d

αi1,i2,...,inxi11 xi2

2 · · ·xinn ;

simply check whether all coefficients αi1,i2,...,in ∈ F are zero. It becomes non-trivial when the polynomial is given in a form different from sum-of-products.For example:

P (u, v, x, y) = (ux+ vy)2 + (vx − uy)2 − (u2 + v2) · (x2 + y2).

One can try expressing such polynomials as sum-of-products and then checking ifthey are zero, however, the size of the resulting polynomial can become exponen-tial and so this method is not efficient. A general representation of polynomialsis via arithmetic circuits: these define a sequence of addition and multiplicationoperations starting from variables and ending in the desired polynomial. Forexample, the second polynomial is expressed as arithmetic circuit below:

* N Rama Rao Professor, Indian Institute of Technology, Kanpur. Research supportedby J C Bose Fellowship FLW/DST/CS/20060225

XVI M. Agrawal

+

∗

+

∗ ∗

∗

+

∗

u

∗

v

+

∗

x

∗

y

∗

+

∗ ∗

−1

2 2

2 2 2 2

−1

P (u, v, x, y) = (ux+ vy)2 + (vx− uy)2 − (u2 + v2) · (x2 + y2)

In the above figure, the operations are inside circles and take as input poly-nomials on arrows coming into the circles and output the resulting polynomialon arrows going out of the circles. If a constant c is present on an arrow carryingpolynomial Q into an addition operation, the polynomial is replaced by cQ, andif the arrow is going into a multiplication operation, the polynomial is replacedby Qc. The size of an arithmetic circuit is defined to be the number of opera-tions in the circuit. So, for example, the size of the above circuit is 16. Anotherimportant parameter associated with an arithmetic circuit is its depth: depth ofan arithmetic circuit is the length of the longest chain of arrows from an inputvariable to the output polynomial. In the above example circuit, the depth is 4.

PIT has had long and interesting history. A randomized polynomial timealgorithm for solving it was given by Schwartz and Zippe[Sch80,Zip79]. Sincethen, several other randomized polynomial-time algorithms have been shown[CK97,LV98,AB03], but no deterministic polynomial time algorithm for theproblem is known till date. In 2002, two important results were shown for PIT:Kabanets and Impagliazzo [KI04] showed that a determinsitic algorithm for PITwould imply a lower bound on arithmetic complexity of an explicit polynomialcomputable in NEXP(this was subsequently extended in [Agr05,AV08,GKKS13]);Agrawal, Kayal, and Saxena [AKS04] derandomized the randomized polynomialtime algorithm for a special kind of PITs, resulting in a deterministic polyno-mial time algorithm for primality testing. Since then, the problem has come tooccupy center-stage in complexity theory and a lot of subsequent developmenthas taken place [KS07,SS13,ASSS12].

Polynomial Identity Testing XVII

References

[AB03] Agrawal, M., Biswas, S.: Primality and identity testing via chinese remain-dering. J. ACM 50(4), 429–443 (2003)

[Agr05] Agrawal, M.: Proving lower bounds via pesudo-random generators. In: Pro-ceedings of the FST&TCS, pp. 96–105 (2005)

[AKS04] Agrawal, M., Kayal, N., Saxena, N.: PRIMES is in P. Annals of Mathemat-ics 160(2), 781–793 (2004)

[ASSS12] Agrawal, M., Saha, C., Saptharishi, R., Saxena, N.: Jacobian hits circuits:Hitting sets, lower bounds for depth-d occur-k formulas and depth-3 tran-scendence degree-k circuits. In: Proceedings of Annual ACM Symposium onthe Theory of Computing, pp. 599–614 (2012)

[AV08] Agrawal, M., Vinay, V.: Arithmetic circuits: A chasm at depth four. In: Pro-ceedings of Annual IEEE Symposium on Foundations of Computer Science,pp. 67–75 (2008)

[CK97] Chen, Z.-Z., Kao, M.-Y.: Reducing randomness via irrational numbers. In:Proceedings of Annual ACM Symposium on the Theory of Computing, pp.200–209 (1997)

[GKKS13] Gupta, A., Kamath, P., Kayal, N., Saptharishi, R.: Arithmetic circuits:A chasm at depth three. In: Proceedings of Annual IEEE Symposium onFoundations of Computer Science, pp. 578–587 (2013)

[KI04] Kabanets, V., Impagliazzo, R.: Derandomizing polyonmial identity testsmeans proving circuit lower bounds. Computational Complexity 13, 1–46(2004)

[KS07] Kayal, N., Saxena, N.: Polynomial identity testing for depth 3 circuits. Com-putational Complexity 16(2), 115–138 (2007)

[LV98] Lewin, D., Vadhan, S.: Checking polynomial identities over any field: To-wards a derandomization? In: Proceedings of Annual ACM Symposium onthe Theory of Computing, pp. 428–437 (1998)

[Sch80] Schwartz, J.T.: Fast probabilistic algorithms for verification of polynomialidentities. J. ACM 27(4), 701–717 (1980)

[SS13] Saxena, N., Seshadri, C.: From Sylvester-Gallai configurations to rankbounds: Improved black-box identity test for depth3 circuits. J. ACM 60(5),article 33 (2013)

[Zip79] Zippel, R.E.: Probabilistic algorithms for sparse polynomials. In: Ng, K.W.(ed.) EUROSAM 1979 and ISSAC 1979. LNCS, vol. 72, pp. 216–226.Springer, Heidelberg (1979)

Power of Enumeration — BDD/ZDD-Based

Methods for Indexing Combinatorial Patterns

Shin-ichi Minato

Graduate School of Information Science and Technology, Hokkaido University/JST ERATO MINATO Discrete Structure Manipulation System Project,

Sapporo, 060-0814, Japan

Abstract

Discrete structures are foundational material for computer science and mathe-matics, which are related to set theory, symbolic logic, inductive proof, graphtheory, combinatorics, probability theory, etc. Many problems are decomposedinto discrete structures using simple primitive algebraic operations.

A Binary Decision Diagram (BDD) is a representation of a Boolean function,one of the most basic models of discrete structures. After the epoch-makingpaper [1] by Bryant in 1986, BDD-based methods have attracted a great dealof attention. The BDD was originally invented for the efficient Boolean functionmanipulation required in VLSI logic design, but Boolean functions are also usedfor modeling many kinds of combinatorial problems. A Zero-suppressed BDD(ZDD) [3] is a variant of the BDD, customized for representing and indexingcombinatorial patterns. ZDDs have been successfully applied not only to VLSIdesign, but also for solving various combinatorial problems, such as constraintsatisfaction, frequent pattern mining, and graph enumeration. Recently, ZDDshave become more widely known, since D.E. Knuth intensively discussed ZDD-based algorithms in the latest volume of his famous series of books [2].

Although a quarter of a century has passed since Bryant first put forth hisidea, there are still many interesting and exciting research topics related to BDDsand ZDDs [4]. One of the most important topics would be that Knuth presenteda surprisingly fast algorithm “Simpath” [2] to construct a ZDD which representsall the paths connecting two points in a given graph structure. This work isimportant because many kinds of practical problems are efficiently solved bysome variations of this algorithm. We generically call such ZDD constructionmethods “frontier-based methods.”

In this talk, we present recent research activity related to BDDs and ZDDs.We first briefly explain the basic techniques for BDD/ZDD manipulation, and wethen show an overview of the frontier-based method for efficiently enumeratingand indexing the solutions of combinatorial problems. We also present severaltopics on various applications of those state-of-the-art techniques.

Power of Enumeration XIX

References

1. Bryant, R.E.: Graph-based algorithms for Boolean function manipulation. IEEETransactions on Computers C-35(8), 677–691 (1986)

2. Knuth, D.E.: The Art of Computer Programming: Bitwise Tricks & Techniques;Binary Decision Diagrams, vol. 4, fascicle 1. Addison-Wesley (2009)

3. Minato, S.-I.: Zero-suppressed BDDs for set manipulation in combinatorial prob-lems. In: Proc. of 30th ACM/IEEE Design Automation Conference (DAC 1993),pp. 272–277 (1993)

4. Minato, S.-I.: Techniques of BDD/ZDD: Brief history and recent activity. IEICETransactions on Information and Systems E96-D(7), 1419–1429 (2013)

Encoding Data Structures�

Rajeev Raman

University of Leicester, UK

Abstract. In recent years, there has been an explosion of interest insuccinct data structures, which store the given data in compact or com-pressed formats and answer queries on the data rapidly while it is stillin its compressed format. Our focus in this talk is to introduce encod-ing data structures. Encoding data structures consider the data togetherwith the queries and aim to store only as much information about thedata as is needed to store the queries. Once this is done, the original datacan be deleted. In many cases, one can obtain space-efficient encodingdata structures even when the original data is incompressible.

* A full version of the invited talk can be found on p. 1.

Table of Contents

Invited Contribution

Encoding Data Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Rajeev Raman

Approximation Algorithms

Fast Algorithms for Constrained Graph Density Problems . . . . . . . . . . . . . 8Venkatesan Chakaravarthy, Neelima Gupta, Aditya Pancholi,and Sambuddha Roy

The Directed Ring Loading with Penalty Cost . . . . . . . . . . . . . . . . . . . . . . . 20Li Guan, Jianping Li, Xuejie Zhang, and Weidong Li

Edge-Colorings of Weighted Graphs (Extended Abstract) . . . . . . . . . . . . . 32Yuji Obata and Takao Nishizeki

Unit Covering in Color-Spanning Set Model . . . . . . . . . . . . . . . . . . . . . . . . . 44Ehsan Emamjomeh-Zadeh, Mohammad Ghodsi, Hamid Homapour,and Masoud Seddighin

Data Structures and Algorithms

Compact Encodings and Indexes for the Nearest Larger NeighborProblem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Seungbum Jo, Rajeev Raman, and Srinivasa Rao Satti

A Practical Succinct Data Structure for Tree-Like Graphs . . . . . . . . . . . . . 65Johannes Fischer and Daniel Peters

Forming Plurality at Minimum Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Wei-Yin Lin, Yen-Wei Wu, Hung-Lung Wang, and Kun-Mao Chao

Approximate Distance Oracle in O(n2) Time and O(n) Space forChordal Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Gaurav Singh, N.S. Narayanaswamy, and G. Ramakrishna

Computational Geometry

Straight-Path Queries in Trajectory Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Mark de Berg and Ali D. Mehrabi

XXII Table of Contents

Folding a Paper Strip to Minimize Thickness . . . . . . . . . . . . . . . . . . . . . . . . 113Erik D. Demaine, David Eppstein, Adam Hesterberg, Hiro Ito,Anna Lubiw, Ryuhei Uehara, and Yushi Uno

An Almost Optimal Algorithm for Voronoi Diagrams of Non-disjointLine Segments (Extended Abstract) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Sang Won Bae

Combinatorial Algorithms

PTAS’s for Some Metric p-source Communication Spanning TreeProblems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Santiago V. Ravelo and Carlos E. Ferreira

Fault-Tolerant Gathering of Asynchronous Oblivious Mobile Robotsunder One-Axis Agreement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

Subhash Bhagat, Sruti Gan Chaudhuri,and Krishnendu Mukhopadhyaya

Enumerating Eulerian Trails via Hamiltonian Path Enumeration . . . . . . . 161Hiroyuki Hanada, Shuhei Denzumi, Yuma Inoue, Hiroshi Aoki,Norihito Yasuda, Shogo Takeuchi, and Shin-ichi Minato

Distributed and Online Algorithms

The Impact of Communication Patterns on Distributed Self-AdjustingBinary Search Trees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

Thim Strothmann

An Efficient Silent Self-Stabilizing Algorithm for 1-Maximal Matchingin Anonymous Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Yuma Asada and Michiko Inoue

Dynamic Online Multiselection in Internal and External Memory . . . . . . 199Jeremy Barbay, Ankur Gupta, Srinivasa Rao Satti,and Jonathan Sorenson

Competitive Analysis for Multi-objective Online Algorithms . . . . . . . . . . . 210Morten Tiedemann, Jonas Ide, and Anita Schobel

Graph Drawing and Algorithms

Simultaneous Drawing of Planar Graphs with Right-Angle Crossingsand Few Bends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

Michael A. Bekos, Thomas C. van Dijk, Philipp Kindermann,and Alexander Wolff

Table of Contents XXIII

An Improved Algorithm for Parameterized Edge Dominating SetProblem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

Ken Iwaide and Hiroshi Nagamochi

On Bar (1, j)-Visibility Graphs (Extended Abstract) . . . . . . . . . . . . . . . . . 246Franz J. Brandenburg, Niklas Heinsohn, Michael Kaufmann,and Daniel Neuwirth

Simultaneous Time-Space Upper Bounds for Red-Blue Path Problemin Planar DAGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

Diptarka Chakraborty and Raghunath Tewari

Combinatorial Problems and Complexity

Non-repetitive Strings over Alphabet Lists . . . . . . . . . . . . . . . . . . . . . . . . . . 270Neerja Mhaskar and Michael Soltys

Dichotomy Theorems for Homomorphism Polynomials of GraphClasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

Christian Engels

Common Unfolding of Regular Tetrahedron and Johnson-ZalgallerSolid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

Yoshiaki Araki, Takashi Horiyama, and Ryuhei Uehara

Threshold Circuits for Global Patterns in 2-Dimensional Maps . . . . . . . . . 306Kei Uchizawa, Daiki Yashima, and Xiao Zhou

Graph Enumeration and Algorithms

Superset Generation on Decision Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . 317Takahisa Toda, Shogo Takeuchi, Koji Tsuda, and Shin-ichi Minato

On Triangle Cover Contact Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323Md. Iqbal Hossain, Shaheena Sultana, Nazmun Nessa Moon,Tahsina Hashem, and Md. Saidur Rahman

Logspace and FPT Algorithms for Graph Isomorphism for Subclassesof Bounded Tree-Width Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329

Bireswar Das, Murali Krishna Enduri, and I. Vinod Reddy

Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335

Competitive Analysis for Multi-objective Online Algorithms . . . . . . . . . . .Morten Tiedemann, Jonas Ide, and Anita Schobel

E1

Erratum