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36
A Generic Type System for the PiCalculus
 Theoretical Computer Science
, 2003
"... We propose a general, powerful framework of type systems for the #calculus, and show that we can obtain as its instances a variety of type systems guaranteeing nontrivial properties like deadlockfreedom and racefreedom. A key idea is to express types and type environments as abstract processe ..."
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Cited by 91 (8 self)
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We propose a general, powerful framework of type systems for the #calculus, and show that we can obtain as its instances a variety of type systems guaranteeing nontrivial properties like deadlockfreedom and racefreedom. A key idea is to express types and type environments as abstract processes: We can check various properties of a process by checking the corresponding properties of its type environment. The framework clarifies the essence of recent complex type systems, and it also enables sharing of a large amount of work such as a proof of type preservation, making it easy to develop new type systems.
Statedependent representation independence
 In Proceedings of the 36th ACM SIGPLANSIGACT Symposium on Principles of Programming Languages
, 2009
"... Mitchell’s notion of representation independence is a particularly useful application of Reynolds ’ relational parametricity — two different implementations of an abstract data type can be shown contextually equivalent so long as there exists a relation between their type representations that is pre ..."
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Cited by 63 (19 self)
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Mitchell’s notion of representation independence is a particularly useful application of Reynolds ’ relational parametricity — two different implementations of an abstract data type can be shown contextually equivalent so long as there exists a relation between their type representations that is preserved by their operations. There have been a number of methods proposed for proving representation independence in various pure extensions of System F (where data abstraction is achieved through existential typing), as well as in Algol or Javalike languages (where data abstraction is achieved through the use of local mutable state). However, none of these approaches addresses the interaction of existential type abstraction and local state. In particular, none allows one to prove representation independence results for generative ADTs — i.e., ADTs that both maintain some local state and define abstract types whose internal
Syntactic Type Abstraction
 ACM TOPLAS
, 2000
"... data types; F.3.2 [Logics and Meanings of Programs]: Semantics of Programming LanguagesOperational Semantics; F.3.3 [Logics and Meanings of Programs]: Studies of Program ConstructsType Structure General Terms: Languages, Security, Theory, Verification Additional Key Words and Phrases: Opera ..."
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Cited by 52 (1 self)
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data types; F.3.2 [Logics and Meanings of Programs]: Semantics of Programming LanguagesOperational Semantics; F.3.3 [Logics and Meanings of Programs]: Studies of Program ConstructsType Structure General Terms: Languages, Security, Theory, Verification Additional Key Words and Phrases: Operational semantics, parametricity, proof techniques, syntactic proofs, type abstraction 1.
SafeDPi: A language for controlling mobile code
 In Proc. FOSSACS, LNCS 2987
, 2003
"... Abstract. safeDpi is a distributed version of the Picalculus, in which processes are located at dynamically created sites. Parametrised code may be sent between sites using socalled ports, which are essentially higherorder versions of Picalculus communication channels. A host location may protect ..."
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Cited by 43 (5 self)
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Abstract. safeDpi is a distributed version of the Picalculus, in which processes are located at dynamically created sites. Parametrised code may be sent between sites using socalled ports, which are essentially higherorder versions of Picalculus communication channels. A host location may protect itself by only accepting code which conforms to a given type associated to the incoming port. We define a sophisticated static type system for these ports, which restrict the capabilities and access rights of any processes launched by incoming code. Dependent and existential types are used to add flexibility, allowing the behaviour of these launched processes, encoded as process types, to depend on the host’s instantiation of the incoming code. We also show that a natural contextually defined behavioural equivalence can be characterised coinductively, using bisimulations based on typed actions. The characterisation is based on the idea of knowledge acquisition by a testing environment and makes explicit some of the subtleties of determining equivalence in this language of highly constrained distributed code. 1
An observationally complete program logic for imperative higherorder functions
 In Proc. LICS’05
, 2005
"... Abstract. We propose a simple compositional program logic for an imperative extension of callbyvalue PCF, built on Hoare logic and our preceding work on program logics for pure higherorder functions. A systematic use of names and operations on them allows precise and general description of comple ..."
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Cited by 39 (11 self)
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Abstract. We propose a simple compositional program logic for an imperative extension of callbyvalue PCF, built on Hoare logic and our preceding work on program logics for pure higherorder functions. A systematic use of names and operations on them allows precise and general description of complex higherorder imperative behaviour. The proof rules of the logic exactly follow the syntax of the language and can cleanly embed, justify and extend the standard proof rules for total correctness of Hoare logic. The logic offers a foundation for general treatment of aliasing and local state on its basis, with minimal extensions. After establishing soundness, we prove that valid assertions for programs completely characterise their behaviour up to observational congruence, which is proved using a variant of finite canonical forms. The use of the logic is illustrated through reasoning examples which are hard to assert and infer using existing program logics.
Logical Relations for Encryption
, 2002
"... The theory of relational parametricity and its logical relations proof technique are powerful tools for reasoning about information hiding in the polymorphic calculus. We investigate the application of these tools in the security domain by defining a cryptographic calculusan extension of the ..."
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Cited by 38 (2 self)
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The theory of relational parametricity and its logical relations proof technique are powerful tools for reasoning about information hiding in the polymorphic calculus. We investigate the application of these tools in the security domain by defining a cryptographic calculusan extension of the standard simply typed calculus with primitives for encryption, decryption, and key generation and introducing syntactic logical relations (in the style of Pitts and BirkedalHarper) for this calculus that can be used to prove behavioral equivalences between programs that use encryption. We illustrate
Environmental bisimulations for higherorder languages
 In TwentySecond Annual IEEE Symposium on Logic in Computer Science
, 2007
"... Developing a theory of bisimulation in higherorder languages can be hard. Particularly challenging can be: (1) the proof of congruence, as well as enhancements of the bisimulation proof method with “upto context ” techniques, and (2) obtaining definitions and results that scale to languages with d ..."
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Cited by 35 (11 self)
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Developing a theory of bisimulation in higherorder languages can be hard. Particularly challenging can be: (1) the proof of congruence, as well as enhancements of the bisimulation proof method with “upto context ” techniques, and (2) obtaining definitions and results that scale to languages with different features. To meet these challenges, we present environmental bisimulations, a form of bisimulation for higherorder languages, and its basic theory. We consider four representative calculi: pure λcalculi (callbyname and callbyvalue), callbyvalue λcalculus with higherorder store, and then HigherOrder πcalculus. In each case: we present the basic properties of environmental bisimilarity, including congruence; we show that it coincides with contextual equivalence; we develop some upto techniques, including upto context, as examples of possible enhancements of the associated bisimulation method. Unlike previous approaches (such as applicative bisimulations, logical relations, SumiiPierceKoutavasWand), our method does not require induction/indices on evaluation derivation/steps (which may complicate the proofs of congruence, transitivity, and the combination with upto techniques), or sophisticated methods such as Howe’s for proving congruence. It also scales from the pure λcalculi to the richer calculi with simple congruence proofs. 1
What are polymorphicallytyped ambients
, 2000
"... www.cs.bu.edu/fac/kfoury The Ambient Calculus was developed by Cardelli and Gordon as a formal framework to study issues of mobility and migrant code [CG98]. We consider an Ambient Calculus where ambients transport and exchange programs rather that just inert data. We propose different senses in whi ..."
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Cited by 32 (5 self)
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www.cs.bu.edu/fac/kfoury The Ambient Calculus was developed by Cardelli and Gordon as a formal framework to study issues of mobility and migrant code [CG98]. We consider an Ambient Calculus where ambients transport and exchange programs rather that just inert data. We propose different senses in which such a calculus can be said to be polymorphically typed, and design accordingly a polymorphic type system for it. Our type system assigns types to embedded programs and what we call behaviors to processes; a denotational semantics of behaviors is then proposed, here called trace semantics, underlying much of the remaining analysis. We state and prove a Subject Reduction property for our polymorphicallytyped calculus. Based on techniques borrowed from finite automata theory, typechecking of fully typeannotated processes is shown to be decidable. Our polymorphicallytyped calculus is a conservative extension of the typed Ambient Calculus originally proposed by Cardelli and Gordon [CG99].
Sequentiality and the πCalculus
, 2001
"... We present a simple type discipline for the πcalculus which precisely captures the notion of sequential functional computation as a specific class of name passing interactive behaviour. The typed calculus allows direct interpretation of both callbyname and callbyvalue sequential functions. T ..."
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Cited by 29 (15 self)
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We present a simple type discipline for the πcalculus which precisely captures the notion of sequential functional computation as a specific class of name passing interactive behaviour. The typed calculus allows direct interpretation of both callbyname and callbyvalue sequential functions. The precision of the representation is demonstrated by way of a fully abstract encoding of PCF.
Bounded Polymorphism in Session Types
, 2003
"... We review work on session types and the πcalculus, and give an example identifying a use for bounded polymorphic types in this setting. We then define a variant of the πcalculus with the appropriate syntax, and propose a static bounded polymorphic type system, for which we prove type soundness. We ..."
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Cited by 24 (5 self)
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We review work on session types and the πcalculus, and give an example identifying a use for bounded polymorphic types in this setting. We then define a variant of the πcalculus with the appropriate syntax, and propose a static bounded polymorphic type system, for which we prove type soundness. We use our rules to give a typing derivation and show the sequence of reductions in our example. Finally, we discuss related work and possible future work in this area.