This volume constitutes the proceedings of the Second Symposium on Programs asDataObjects(PADO-II),heldattheUniversityofAarhus,Denmark,onMay 21–23,2001. PADO-IIwascolocatedwiththeThirdInternationalWorkshopon Implicit Computational Complexity (ICC2001) and the Seventeenth Conference on the Mathematical Foundations of Programming Semantics (MFPS XVII). The?rstPADOwasorganizedbyHaraldGanzingerandNeilJones,in1985. This second symposium took place at the occasion of Neil Jones’s 60th birthday, andonhiswish,weorganizeditasaresearchevent. Thecallforpaperswas openandelicited30submissionsfrom12countries. Overall,145reviewswere collected,andbasedonthese,theprogramcommitteeselected14papersfor presentation. Withoneexception,eachsubmissionreceivedatleast4reviews. Whererelevant,atranscriptofthe(electronic)PCmeetingwasalsoenclosed.^ 1 PADO-IIwassponsoredbyBRICS andthe EspritWorkingGroupAPPSEM, and organized in cooperation with the European Association for Programming Languages and Systems (EAPLS) and the Special Interest Group on Progr- ming Languagesof the Association for Computing Machinery (ACM SIGPLAN). We gratefully acknowledge their support. We also extend our thanks to the PC members and external reviewers for theirtimeandthoughts,JanneKrounChristensenandKarenKjærMøllerfor theirorganizationalhelp,the project for hosting our submission web site,andDanielDamianforsettingitupandmaintainingit. February 2001 Olivier Danvy and Andrzej Filinski 1 BasicResearchinComputerScience(www. brics. dk), fundedbytheDanishNationalResearchFoundation.^ ConferenceOrganization Conference Co-chairs OliverDanvy,BRICS,UniversityofAarhus,Denmark AndrzejFilinski,BRICS,UniversityofAarhus,Denmark Program Committee TorbenAmtoft BostonUniversity,USA CharlesConsel LaBRI/ENSERB,France CatarinaCoquand ChalmersUniversity,Sweden RadhiaCousot EcolePolytechnique,France OlivierDanvy UniversityofAarhus,Denmark AndrzejFilinski UniversityofAarhus,Denmark YoshihikoFutamura WasedaUniversity,Japan FritzHenglein ITUniversity,Denmark PeterLee CarnegieMellonUniversity,USA Y. AnnieLiu SUNYStonyBrook,USA DaveMacQueen BellLabs,USA JamesS. Royer SyracuseUniversity,USA MortenHeineSørensen ITPractice,Denmark CarolynL. Talcott StanfordUniversity,USA JonLWhite CommerceOne,Inc. ,USA Additional Referees ZinoBenaissa,EdoardoS. Biagioni,HowardA. Blair,CraigChambers,Wei- NganChin,LarsR. Clausen,PierreCointe,ThierryCoquand,NielsDamgaard, DanielDamian,DamienDoligez,R´emiDouence,R.^ KentDybvig,PavelEmel- nov,GilbertoFil´e,JohnGallagher,RobertoGiacobazzi,RobertGl¨ uck,John Hatcli?,NevinHeintze,ThomasHildebrandt,ZhenjiangHu,DieterHutter, KazuhikoKakehi,JerzyKarczmarczuk,AndyKing,NaokiKobayashi,Zenjiro Konishi,KimG. Larsen,MarioLatendresse,JuliaL. Lawall,MichaelLeuschel, JakobLichtenberg,FrancescoLogozzo,HenningMakholm,JacquesMalenfant, BrianMayoh,AntoineMin´e,TorbenÆ. Mogensen,EugenioMoggi,DavidM- niaux,PeterD. Mosses,JoachimNiehren,SusanOlder,AlbertoPettorossi, Franco ¸isPottier,MaurizioProietti,AarneRanta,JakobRehof,JohnReppy, Laurent R´ eveill`ere,MartinC. Rinard,Kristo?erH. Rose,AbhikRoychoudhury, LouisSalvail,Jo˜aoSaraiva,DavidA. Schmidt,JensPeterSecher,MarioS¨udholt, S. DoaitseSwierstra,HaraldSøndergaard,ArnaudVenet,HongweiXi,ZheYang, Kwangkeun Yi. TableofContents InvitedOpeningTalk Program Analysis for Implicit Computational Complexity. . . . . . . . . . . . . . . 1 NeilD.^ Jones ContributedPapers Deriving Pre-conditions for Array Bound Check Elimination. . . . . . . . . . . . . 2 Wei-NganChin,Siau-ChengKhoo,DanaN. Xu Type Systems for Useless-Variable Elimination. . . . . . . . . . . . . . . . . . . . . . . . . 25 AdamFischbach,JohnHannan Boolean Constraints for Binding-Time Analysis. . . . . . . . . . . . . . . . . . . . . . . . 39 KevinGlynn,PeterJ. Stuckey,MartinSulzmann,HaraldSøndergaard Constraint Abstractions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 J¨orgenGustavsson,JosefSvenningsson Implementing Circularity Using Partial Evaluation. . . . . . . . . . . . . . . . . . . . .