ARTIFICIAL INTELLIGENCE RESEARCH AND DEVELOPMENT Frontiers in Artificial Intelligence and Applications FAIA covers all aspects of theoretical and applied artificial intelligence research in the form of monographs, doctoral dissertations, textbooks, handbooks and proceedings volumes. The FAIA series contains several sub-series, including “Information Modelling and Knowledge Bases” and “Knowledge-Based Intelligent Engineering Systems”. It also includes the biennial ECAI, the European Conference on Artificial Intelligence, proceedings volumes, and other ECCAI – the European Coordinating Committee on Artificial Intelligence – sponsored publications. An editorial panel of internationally well-known scholars is appointed to provide a high quality selection. Series Editors: J. Breuker, R. Dieng-Kuntz, N. Guarino, J.N. Kok, J. Liu, R. López de Mántaras, R. Mizoguchi, M. Musen, S.K. Pal and N. Zhong Volume 184 Recently published in this series Vol. 183. C. Eschenbach and M. Grüninger (Eds.), Formal Ontology in Information Systems – Proceedings of the Fifth International Conference (FOIS 2008) Vol. 182. H. Fujita and I. Zualkernan (Eds.), New Trends in Software Methodologies, Tools and Techniques – Proceedings of the seventh SoMeT_08 Vol. 181. A. Zgrzywa, K. Choroś and A. Siemiński (Eds.), New Trends in Multimedia and Network Information Systems Vol. 180. M. Virvou and T. Nakamura (Eds.), Knowledge-Based Software Engineering – Proceedings of the Eighth Joint Conference on Knowledge-Based Software Engineering Vol. 179. A. Cesta and N. Fakotakis (Eds.), STAIRS 2008 – Proceedings of the Fourth Starting AI Researchers’ Symposium Vol. 178. M. Ghallab et al. (Eds.), ECAI 2008 – 18th European Conference on Artificial Intelligence Vol. 177. C. Soares et al. (Eds.), Applications of Data Mining in E-Business and Finance Vol. 176. P. Zaraté et al. (Eds.), Collaborative Decision Making: Perspectives and Challenges Vol. 175. A. Briggle, K. Waelbers and P.A.E. Brey (Eds.), Current Issues in Computing and Philosophy Vol. 174. S. Borgo and L. Lesmo (Eds.), Formal Ontologies Meet Industry Vol. 173. A. Holst et al. (Eds.), Tenth Scandinavian Conference on Artificial Intelligence – SCAI 2008 Vol. 172. Ph. Besnard et al. (Eds.), Computational Models of Argument – Proceedings of COMMA 2008 Vol. 171. P. Wang et al. (Eds.), Artificial General Intelligence 2008 – Proceedings of the First AGI Conference ISSN 0922-6389 Artificial Intelligence Research and Development Proceedings of the 11th International Conference of the Catalan Association for Artificial Intelligence Edited by Teresa Alsinet Department of Computer Science, Universitat de Lleida, Spain Josep Puyol-Gruart Institut d’Investigació en Intel·ligència Artificial, CSIC, Spain and Carme Torras Institut de Robòtica i Informàtica Industrial, CSIC-UPC, Spain Amsterdam • Berlin • Oxford • Tokyo • Washington, DC © 2008 The authors and IOS Press. All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without prior written permission from the publisher. ISBN 978-1-58603-925-7 Library of Congress Control Number: 2008936675 Publisher IOS Press Nieuwe Hemweg 6B 1013 BG Amsterdam Netherlands fax: +31 20 687 0019 e-mail: [email protected] Distributor in the UK and Ireland Distributor in the USA and Canada Gazelle Books Services Ltd. IOS Press, Inc. White Cross Mills 4502 Rachael Manor Drive Hightown Fairfax, VA 22032 Lancaster LA1 4XS USA United Kingdom fax: +1 703 323 3668 fax: +44 1524 63232 e-mail: [email protected] e-mail: [email protected] LEGAL NOTICE The publisher is not responsible for the use which might be made of the following information. PRINTED IN THE NETHERLANDS v Conference Organization The CCIA 2008 conference was organized by the Associació Catalana d’Intel·ligència ArtificialandtheInstitutd’InvestigacióenIntel·ligènciaArtificial,CSIC. GeneralChair CarmeTorras,InstitutdeRobòticaiInformàticaIndustrial,CSIC-UPC OrganizingChair JosepPuyol-Gruart,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC ProgramCommitteeChair TeresaAlsinet,UniversitatdeLleida ScientificCommittee NúriaAgell,UniversitatRamonLlull JosepAguilar,Laboratoired’Architectureetd’AnalysedesSystèmes,CNRS GuillemAlenyà,InstitutdeRobòticaiInformàticaIndustrial,CSIC-UPC RenéAlquézar,UniversitatPolitècnicadeCatalunya CecilioAngulo,UniversitatPolitècnicadeCatalunya CarlosAnsótegui,UniversitatdeLleida EvaArmengol,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC EsterBernardó-Mansilla,UniversitatRamonLlull XavierBinefa,UniversitatAutònomadeBarcelona VicentBotti,UniversidadPolitécnicadeValencia MiguelÁngelCazorla,Universitatd’Alacant JesúsCerquides,UniversitatdeBarcelona CarlosIvánChesñevar,UniversidadNacionaldelSur,Argentina UlisesCortés,UniversitatPolitècnicadeCatalunya JosepLluísdelaRosa,UniversitatdeGirona TeresaEscrig,UniversitatJaumeI MarcEsteva,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC FrancescFerri,UniversitatdeValència JosepMariaGarrell,UniversitatRamonLlull HéctorGeffner,UniversitatPompeuFabra LluísGodo,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC ElisabetGolobardes,UniversitatRamonLlull JordiLevy,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC ChuMinLi,UniversitédePicardie AngelesLópez,UniversitatJaumeI BeatrizLópez,UniversitatdeGirona RamonLópezdeMántaras,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC MaiteLópez-Sánchez,UniversitatdeBarcelona vi GáborLugosi,UniversitatPompeuFabra FelipManyà,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC RodrigoMartínez,UniversidaddeMurcia DavidMasip,UniversitatObertadeCatalunya JoaquimMeléndez,UniversitatdeGirona VioletaMigallón,Universitatd’Alacant BernardoMorcego,UniversitatPolitècnicadeCatalunya AntonioMoreno,UniversitatRoviraiVirgili PabloNoriega,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC JordiPlanes,UniversitatdeLleida EnricPlaza,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC MoniquePolit,UniversitédePerpignan‘ViaDomitia’ OriolPujol,UniversitatdeBarcelona PetiaRadeva,UniversitatAutònomadeBarcelona JordiRecasens,UniversitatPolitècnicadeCatalunya DavidRiaño,UniversitatRoviraiVirgili JuanAntonioRodríguez,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC HoracioRodríguez,UniversitatPolitècnicadeCatalunya IgnasiRodríguez-Roda,UniversitatdeGirona JordiSabater-Mir,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC MiquelSànchez-Marrè,UniversitatPolitècnicadeCatalunya SandraSandri,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC VicençTorra,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC AïdaValls,UniversitatRoviraiVirgili LlorençValverde,UniversitatdelesIllesBalears MariaVanrell,UniversitatAutònomadeBarcelona WambertoVasconcelos,UniversityofAberdeen GlòriaVázquez,UniversitatdeLleida JordiVitrià,UniversitatAutònomadeBarcelona AdditionalReferees JosepArgelich,FernandodelaRosa,IsabelaDrummond,PereGarcia-Calvés OrganizingCommittee LluísGodo,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC EvaArmengol,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC JoaquimMeléndez,UniversitatdeGirona OrganizingInstitutions AssociacióCatalana Institutd’Investigació d’Intel·ligènciaArtificial enIntel·ligènciaArtificial vii SponsoringInstitutions This page intentionally left blank Artificial Intelligence Research and Development ix T. Alsinet et al. (Eds.) IOS Press, 2008 © 2008 The authors and IOS Press. All rights reserved. Preface TherewasatimewhenAIwasseenbymanyassciencefiction,i.e.,thehealthyen- deavorofspeculatingaboutthefuture.Nowthefutureishere.AIhaspassedfrombeing avisionarydisciplinetolyingatthecoreofmanycommercialenterprises.AIprograms scattered through the web influence nowadays our lives: by extracting profiles and of- fering tailored advertisement, helping us in our searches, establishing social networks, providingentertainment...Andnotjustinthenet,butalsointhephysicalworld.InJapan therearerobotsthatguidecustomersthroughmarketplacesadvisingthemwheretofind the product matching their needs, and realistic replicas of university professors allow themtoteachtheirlecturesahundredkilometersawayfromtheclassroom.Nottospeak aboutintelligentprosthesesandremotehigh-precisionsurgery. In the Catalan-speaking world we do not have robots in marketplaces yet, but it is coming. Recently, the first commercial humanoid robot has been built. Since AI tech- nology is becoming reasonably mature, companies are progressively relying on it. The CatalanAssociationforArtificialIntelligence(ACIA1)triestopromotesynergieswithin the research community and also between the different actors playing a role in the de- velopment of AI: from universities to industry, from governmental departments to the informationsociety,fromentertainmententerprisestocitizenservices. One of the main activities of ACIA is the organization of this annual conference (CCIA),whichreachesits11theditionhereinSantMartíd’Empúries,October22–24, 2008. The good health of basic and applied research in the Catalan AI community and its influence area shows up in the selection of representative papers submitted to CCIA2008,whicharegatheredinthisvolume. The book is organized according to the different areas in which the papers were distributed for their presentation during the conference. Namely: Agents; Constraints, Satisfiability, and Search; Knowledge and Information Systems; Knowledge Represen- tation and Logic; Machine Learning; Multidisciplinary Topics and Applications; Rea- soningaboutPlans,Processes,andActions;Robotics;andUncertaintyinAI.Papersap- pearinginthisvolumeweresubjectedtorigorousblindreview:twoscientificcommittee members (or in some cases, auxiliary reviewers) reviewed each paper under the super- visionoftheprogramchairs.Thescientificcommitteemembersassignedtoeachpaper weredeterminedbasedontheirexpertiseandtheirexpressedinterestinthepaper,with aneyetowardcoverageoftherelevantaspectsofeachpaper.Thisyear54paperswere submitted to CCIA, with 45 accepted for oral or poster presentation at the conference. All accepted papers appear in this volume. The quality of the papers was high in aver- age,andtheselectionbetweenoralorposterpresentationwasonlybasedonthepoten- tialdegreeofdiscussionthatapaperwethoughtcouldgenerate.Webelievethatallthe paperscollectedinthisvolumecanbeofinteresttoanycomputerscientistorengineer interestedinAI. 1ACIA,theCatalanAssociationforArtificialIntelligence,isamemberoftheEuropeanCoordinatingCom- mitteeforArtificialIntelligence(ECCAI).http://www.acia.org. x We would like to express our sincere gratitude to all the authors and members of thescientificandorganizingcommitteesthathavemadethisconferenceasuccess.Our specialthanksgoalsototheplenaryspeakers,RicardoBaeza-YatesandHectorGeffner, fortheireffortinpreparingveryinterestinglectures,andtothepresidentofACIA,Núria Agell,forherkindsupport. SantMartíd’Empúries,October2008 TeresaAlsinet,UniversitatdeLleida JosepPuyol-Gruart,Institutd’InvestigacióenIntel·ligènciaArtificial,CSIC CarmeTorras,InstitutdeRobòticaiInformàticaIndustrial,CSIC-UPC