WolfgangFaber Miros lawTruszczynski ´ Conference Organization ProgramCo-chairs ThomasEiter(ViennaUniversityofTechnology,Austria) Miros lawTruszczynski ´ (UniversityofKentucky,USA) ProgramCommittee AlexanderBochman(HolonAcademicInstituteofTechnology,Israel) PieroBonatti(Universit` adegliStudiMilano/Crema,Italy) GerhardBrewka(UniversityofLeipzig,Germany) JamesDelgrande(SimonFraserUniversity,Canada) MarcDenecker(KatholiekeUniversiteitLeuven,Belgium) NormanFoo(UniversityofNewSouthWales,Australia) MichaelGelfond(TexasTechUniversity,USA) KatsumiInoue(KobeUniversity,Japan) AntonisKakas(UniversityofCyprus) NicolaLeone(Universit` adegliStudidellaCalabria,Italy) VladimirLifschitz(UniversityofTexasatAustin,USA) FangzhenLin(TheHongKongUniversityofScienceandTechnology,China) VictorMarek(UniversityofKentuckyatLexington,USA) ZhangMing-Yi(GuizhouAcademyofSciences,China) IlkkaNiemel¨ a(HelsinkiUniversityofTechnology,Finland) Lu´?sMonizPereira(UniversidadeNovadeLisboa,Portugal) MarcoSchaerf(Universitad ` iRoma"LaSapienza,"Italy) TorstenSchaub(UniversityofPotsdam,Germany) FrancescaToni(ImperialCollege,London,U. K. ) Li-YanYuan(UniversityofAlberta,Canada) Publicity Chair WolfgangFaber(ViennaUniversityofTechnology,Austria) Organization VII Additional Reviewers Jos´eAlferes MehmetOrgun CristinaBaroglio MauricePagnucco KrysiaBroda VivianaPatti MauriceBruynooghe NikolayPelov FrancescoBuccafurri GeraldPfeifer CarlosDam´asio FabrizioRiguzzi EmmanuelDeMot RiccardoRosati YannisDimopoulos GiulianaSabbatini EsraErdem FaribaSadri WolfgangFaber ChiakiSakama DayaGaur FrancescoScarcello JensHappe TommiSyrj¨anen TomiJanhunen AndreaTettamanzi JoohyungLee BertVanNu?elen NicolaLeone HelmutVeith ThomasLinke GerardVreeswijk ThomasLukasiewicz KewenWang PaoloMancarella Jia-HuaiYou CristinelMateis DongmoZhang RobMiller Sponsoring Institutions We would like to acknowledge ?nancial support for the conference from the EuropeanO?ceofAerospaceResearchandDevelopment(EOARD),underc- tractF61775-01-WF077,theAustrianComputerSociety(OCG),theEuropean Commission,theAustrianMinistryofTransport,Innovation&Technology,and Microsoft. Table of Contents Invited Papers AComputationalLogicApproachtoHeterogenousAgentSystems. 1 J¨urgenDix DeclarativeInformationExtraction,WebCrawling, andRecursiveWrappingwithLixto. 21 RobertBaumgartner,SergioFlesca,andGeorgGottlob OntheComplexityofModelCheckingandInference inMinimalModels(ExtendedAbstract). 42 LefterisM. KirousisandPhokionG. Kolaitis DataIntegrationNeedsReasoning. 54 MaurizioLenzerini NonmonotonicInductiveLogicProgramming. 62 ChiakiSakama Regular Papers StrongEquivalenceforLogicPrograms andDefaultTheories(MadeEasy). 81 HudsonTurner OntheE?ectofDefaultNegationontheExpressiveness ofDisjunctiveRules. 93 TomiJanhunen OntheExpressibilityofStableLogicProgramming. 107 V. W. MarekandJ. B. Remmel OntheRelationshipbetweenDefeasibleLogic andWell-FoundedSemantics. 121 GerhardBrewka AComparativeStudyofWell-FoundedSemantics forDisjunctiveLogicPrograms. 133 KewenWang ReasoningwithOpenLogicPrograms. 147 PieroA. Bonatti RepresentationofIncompleteKnowledgebyInduction ofDefaultTheories.