ThisvolumecontainsthepapersfromLOPSTR2001,the11thInternational WorkshoponLogic-basedProgramSynthesisandTransformation. Topicsof- teresttoLOPSTRcoverallaspectsoflogic-basedprogramdevelopmentand,in particular, speci?cation, synthesis, veri?cation, transformation, specialization, analysis,optimization,composition,reuse,component-basedsoftwaredevel- ment,andsoftwarearchitectures. LOPSTR 2001 took place in the Coral Beach Hotel in Paphos (Cyprus) fromNovember28–30,2001. PastLOPSTRworkshopswereheldinManchester, UK(1991,1992,1998),Louvain-la-Neuve,Belgium(1993),Pisa,Italy(1994), Arnhem,TheNetherlands(1995),Stockholm,Sweden(1996),Leuven,Belgium (1997),Venice,Italy(1999),andLondon,UK(2000). LOPSTR2001wasco-locatedwiththe17thInternationalConferenceonLo- 1 gicProgramming(ICLP2001) andthe7thInternationalConferenceonPrinci- 2 plesandPracticeofConstraintProgramming(CP2001) .^ TheLOPSTRc- munitypro?tedalotfromthescienti?cdiscussions,thelecturesoftheinvited speakers,andthevarioussessionsofICLPandCP. I would like to express my gratitude to all the authors of the submitted papersandalltheattendeesfortheircommitmentandcooperation. Amongthe submittedpapers,theProgramCommitteeselected13papersforpresentation. Aftertheworkshop,theauthorswereaskedtosubmitimprovedversionsoftheir paperswhichwerethenreviewedbytheProgramCommittee. The?nalversions havebeencollectedinthisvolume,whichalsoincludesthepaperbyourinvited speaker,NatarajanShankar(StanfordResearchInstitute,MenloPark,USA), onthegenerationofe?cientprogramsfromlogic. MywarmestthanksalsogotoallthemembersoftheProgramCommittee andtheadditionalreviewersfortheirdiligentworkandinvaluablehelp. Iwould liketothankFabioFioravanti(IASI-CNRofRome,Italy),MaurizioProietti (IASI-CNRofRome,Italy),andAntonisKakas(UniversityofCyprus,Cyprus), whoworkedwithmewithgreatenthusiasmanddedicationasmembersofthe OrganizingCommittee.^ Thepre-proceedingsofLOPSTR2001wereprintedbytheIASIInstituteof theNationalResearchCouncilofRome,Italy,andtheDepartmentofComputer ScienceoftheUniversityofCyprusinNicosia. IalsothankSpringerforaccepting topublishthese?nalproceedingsintheLNCSseries. TheLOPSTR2001home pageis:http://www. iasi. rm. cnr. it/˜adp/lopstr01cfp. html. April2002 AlbertoPettorossi 1 Codognet,Ph. ,editor,LogicProgramming—ICLP2001,LectureNotesinComputer Science 2237,Springer-Verlag,2001. 2 Walsh,T. ,editor,PrinciplesandPracticeofConstraintProgramming—CP2001, LectureNotesinComputerScience 2239,Springer-Verlag,2001.^ ProgramChair AlbertoPettorossi Universit`adegliStudidiRoma‘TorVergata’,Italy ProgramCommittee DavidBasin Albert-Ludwigs-Universit¨atFreiburg,Germany AntonioBrogi Universit`adiPisa,Italy MauriceBruynooghe KatholiekeUniversiteitLeuven,Belgium NicolettaCocco Universit`aCa’FoscaridiVenezia,Italy MireilleDucass´e IRISA/INSA,France SandroEtalle TwenteUniversity&CWI,TheNetherlands JohnGallagher UniversityofBristol,UK RobertGluc ¨ k WasedaUniversity,Japan MichaelHanus Christian-Albrechts-Universit¨atzuKiel,Germany ManuelHermenegildo UniversidadPolit´ecnicadeMadrid,Spain PatriciaHill UniversityofLeeds,UK Kung-KiuLau UniversityofManchester,UK MichaelLeuschel UniversityofSouthampton,UK TorbenMogensen UniversityofCopenhagen,Denmark AlbertoPettorossi Universit`adegliStudidiRoma‘TorVergata’,Italy I. V.^ Ramakrishnan StateUniversityofNewYorkatStonyBrook,USA DonSannella UniversityofEdinburgh,UK ZoltanSomogyi UniversityofMelbourne,Australia AdditionalReferees Jos´eAlferes StefanGruner SabinaRossi AnnalisaBossi PaulJackson FaustoSpoto Lu´?sFernandoCastro FrancisKlay MathieuTuruani AlessandraDiPierro GiridharPemmasani WimVanhoof YifeiDong MaurizioProietti FabioFioravanti Germ´anPuebla SponsoringInstitutions TheAssociationforLogicProgramming TheCOLOGNet TheInternationalFederationforComputationalLogic TheIASIInstituteofCNR(Italy) Universit`adegliStudidiRoma‘TorVergata’(Italy) TableofContents InvitedSpeaker Static Analysis for Safe Destructive Updates in a Functional Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 NatarajanShankar(SRIInternational,MenloPark,USA) ProgramTransformationandEquivalence A Transformation Technique for Datalog Programs Based on Non-deterministic Constructs. . . . . . . . . . . . . . . . . . . . . . . .^ . . . . . . . . . . . . . 25 PetrosPotikas,PanosRondogiannis(UniversityofAthens,Greece), ManolisGergatsoulis(InstituteofInformatics&Telecommunications, AghiaParaskeviAttikis,Greece) On Deforesting Parameters of Accumulating Maps . . . . . . . . . . . . . . . . . . . . . 46 KazuhikoKakehi,RobertGluck, ¨ YoshihikoFutamura(Waseda University,Tokyo,Japan) Equivalence in Answer Set Programming. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 MauricioOsorio,JuanA. Navarro,Jos´eArrazola(Universidaddelas Am´ericas,Puebla,M´exico) ProgramVeri?caion Proof Theory, Transformations, and Logic Programming for Debugging Security Protocols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 GiorgioDelzanno(UniversityofGenova,Italy),SandroEtalle(CWI andUniversityofTwente,TheNetherlands) Abstract Conjunctive Partial Deduction Using Regular Types and Its Application to Model Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .