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'?s FernandoCastro 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...7 6 GiorgioDelzanno(UniversityofGenova,Italy),SandroEtalle(CWI andUniversityofTwente,TheNetherlands) Abstract Conjunctive Partial Deduction Using Regular Types and Its Application to Model Checking ...