Symbolic and Quantitative Approaches to Reasoning and Uncertainty

Uncertaintyisanincreasinglyimportantresearchtopicinmanyareasofc- puterscience. Manyformalismsarebeingdeveloped, withmuchinterestatthe theoryleveldirectedatdevelopingabetterunderstandingoftheformalismsand identifyingrelationshipsbetweenformalisms, andatthetechnologyleveldirected atdevelopingsoftwaretoolsforformalismsandapplicationsofformalisms. ThemainEuropeanforumforthesubjectistheEuropeanConferenceon SymbolicandQuantitativeApproachestoReasoningandUncertainty(EC- SQARU). FollowingthesuccessofthepreviousECSQARUconferences, heldin Marseilles(1991), Granada(1993), Fribourg(1995), andBonn(1997), the?fth conferenceintheserieswasheldatUniversityCollegeLondoninJuly1999. ThisvolumecontainspapersacceptedforpresentationatECSQARU'99. In additiontothemainconference, twoworkshopswereheld. The?rstwason DecisionTheoreticandGameTheoreticAgents, chairedbySimonParsonsand MikeWooldridge, andthesecondwasonLogicalandUncertaintyModelsfor InformationSystems, chairedbyFabioCrestaniandMouniaLalmas. Selected papersfromtheworkshopsarealsoincludedintheseproceedings. Weareindebitedtotheprogrammmecommitteefortheire?ortinorganising theprogramme, totheinvitedspeakers, andtothepresentersofthetutorials. Furthermore, wegratefullyacknowledgethecontributionofthemanyreferees whowereinvolvedinthereviewingprocess. Finallywewouldliketothankthe DepartmentofComputerScienceatUniversityCollegeLondonforadminist- tivesupport. ProgrammeCommittee TheprogrammecommitteewaschairedbyAnthonyHunter(UniversityCollege London), andcomprisedDovGabbay(King'sCollegeLondon), FinnJensen (AalborgUniversity), RudolfKruse(UniversityofMagdeburg), SimonParsons (QueenMary, UniversityofLondon)HenriPrade(IRIT, Toulouse), Torsten Schaub(UniversityofPotsdam), andPhilippeSmets(ULB, Bruxelles). Reviewers Theprogrammecommitteeisverygratefulforallthehardworkcontributed bythereviewers. Hopefully, wehavenotmissedanyonefromthefollowing list: BruceD'Ambrosio, FlorenceBannay, SalemBenferhat, PhilippeBesnard, HuguesBersini, ChristianBorgelt, RachelBourne, StefanBrass, LaurenceCholvy, RogerCooke, AdnanDarwiche, YannisDimopoulos, JurgenDix, DidierDubois, UweEgly, LindavanderGaag, JoergGebhardt, SiegfriedGottwald, RolfHaenni, Jean-YvesJa?ray, RadimJirousek, RuthKempson, U?eKjaerulf, FrankK- wonn, AljoschaKlose, JuergKohlas, PaulKrause, GerhardLakemeyer, Mounia Lalmas, JeromeLang, KimG. Larsen, NorbertLehmann, T. Y. Lin, Thomas Linke, KhalidMellouli, JeromeMengin, J. -J. Ch. Meyer, SanjayModgil, Yves Moinard, Sera?nMoral, DetlefNauck, AnnNicholson, PascalNicolas, Dennis VI Preface Nilsson, KristianG. Olesen, RainerPalm, ZdzislawPawlak, VincentRisch, Regis Sabbadin, CamillaSchwind, PrakashP. Shenoy, MilanStudeny, HeikoTimm, HansTompits, MarcoValtorta, andCeesWitteven. April1999 AnthonyHunterandSimonParsons TableofContents Onthedynamicsofdefaultreasoning GrigorisAntoniou. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Non-monotonicandparaconsistentreasoning: Frombasicentailmentsto plausiblerelations OferArieliandArnonAvron . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 AcomparisonofsystematicandlocalsearchalgorithmsforregularCNF formulas Ram´onB´ejarandFelipMany`a. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Query-answeringinprioritizeddefaultlogic FaridBenhammadi, PascalNicolasandTorstenSchaub. . . . . . . . . . . . . . . . . . . . 32 Updatingdirectedbeliefnetworks BoutheinaBenYaghlaneandKhaledMellouli. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .