. . . . . . . 33 SamsonAbramsky 3 OnMereologiesinComputingScience. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 DinesBjorner 4 Roles, Stacks, Histories:ATripleforHoare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Johannes Borgstrom, ¨ Andrew D. Gordon, andRiccardoPucella 5 ForwardwithHoare. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 MikeGordonandHel ´ene ` Collavizza 6 ProbabilisticProgrammingwithCoordination. . . . . . . . . . . . . . . . . . . . . . . . . . . 123 HeJifeng 7 TheOperationalPrincipleandProblemFrames. . . . . . . . . . . . . . . . . . . . . . . . . 143 MichaelJackson 8 TheRoleofAuxiliaryVariablesintheFormal DevelopmentofConcurrentPrograms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 C. B. Jones 9 AvoidaVoid:TheEradicationofNullDereferencing. . . . . . . . . . . . . . . . . . . . 189 BertrandMeyer, AlexanderKogtenkov, andEmmanuelStapf 10 UnfoldingCSP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 MikkelBundgaardandRobinMilner xi xii Contents 11 Quicksort:CombiningConcurrency, Recursion, andMutableDataStructures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 DavidKitchin, AdrianQuark, andJayadevMisra 12 TheThousand-and-OneCryptographers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 A. K. McIverandC. C. Morgan 13 On Process-AlgebraicExtensions of Metric TemporalLogic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 ChristophHaase, Joel ¨ Ouaknine, andJamesWorrell 14 FunwithTypeFunctions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301 OlegKiselyov, SimonPeytonJones, andChung-chiehShan 15 OnCSPandtheAlgebraicTheoryofEffects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 RobvanGlabbeekandGordonPlotkin 16 CSPisExpressiveEnoughfor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371 A. W. Roscoe 17 TheTokeneerExperiments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405 JimWoodcock, EmineGokc ¨ ¸eAydal, andRodChapman Chapter1 Insight, InspirationandCollaboration C. B. JonesandA. W. Roscoe Abstract TonyHoare'smanycontributionstocomputingsciencearemarkedby insightthatwasgroundedinpracticalprogramming. Manyofhispapershavehada profoundimpactontheevolutionofour?eld;theyhavemoreoverprovidedasource ofinspirationtoseveralgenerationsofresearchers. Weexaminethedevelopmentof hisworkthroughareviewofthedevelopmentofsomeofhismostin?uentialpieces ofworksuchasHoarelogic, CSPandUnifyingTheories. 1. 1 Introduction To many who know Tony Hoare only through his publications, they must often looklikepolishedgemsthatcomefromamindthatrarelymakesfalsesteps, nor evenperhapshastoworkattheircreation. Assooften, thisimpressionisafurther complimenttosomeonewhoactuallyaddstoveryhardworkandmanydiscarded attempts the ?nal polish thatmakes complexideas relatively easy for the reader tocomprehend. Asindicatedonpagexiof[HJ89],hisideastypicallygothrough manyrevisions. ThetwoauthorsofthecurrentpapereachhadthehonourofTonyHoaresuperv- ingtheirdoctoralstudiesinOxford. Theyknowat?rsthandhiskindandgenerous styleandwillcountitasanachievementifthispapercanconveysomethingofthe workingmethodsofsomeonebigenoughtoeschewcompetitionandpointscoring. Indeedit willbe apparentfromthe followingsectionshowoften, havingstarted somenewwayofthinkingorexcitingideas, hehappilyleavestheirexplorationand developmenttoothers. Wehavebothbene?tedpersonallyfromthis. C. B. Jones( ) SchoolofComputingScience, NewcastleUniversity, UK e-mail:cliff. jones@ncl. ac. uk A. W. Roscoe OxfordUniversityComputingLaboratory, UK e-mail:Bill. Roscoe@comlab. ox. ac. uk C. B. Jonesetal. (eds. ),Re?ectionsontheWorkofC. A. R. | Reflections on the Work of C. A.R. Hoare by Cliff B. Jones, Hardcover | Indigo Chapters | Reflections on the Work of C.A.R. Hoare by Cliff B. Jones, Hardcover | Indigo Chapters