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A calculus of mobile processes, I
, 1992
"... We present the acalculus, a calculus of communicating systems in which one can naturally express processes which have changing structure. Not only may the component agents of a system be arbitrarily linked, but a communication between neighbours may carry information which changes that linkage. The ..."
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Cited by 1183 (31 self)
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We present the acalculus, a calculus of communicating systems in which one can naturally express processes which have changing structure. Not only may the component agents of a system be arbitrarily linked, but a communication between neighbours may carry information which changes that linkage. The calculus is an extension of the process algebra CCS, following work by Engberg and Nielsen, who added mobility to CCS while preserving its algebraic properties. The rrcalculus gains simplicity by removing all distinction between variables and constants; communication links are identified by names, and computation is represented purely as the communication of names across links. After an illustrated description of how the ncalculus generalises conventional process algebras in treating mobility, several examples exploiting mobility are given in some detail. The important examples are the encoding into the ncalculus of higherorder functions (the Icalculus and combinatory algebra), the transmission of processes as values, and the representation of data structures as processes. The paper continues by presenting the algebraic theory of strong bisimilarity and strong equivalence, including a new notion of equivalence indexed by distinctionsi.e., assumptions of inequality among names. These theories are based upon a semantics in terms of a labeled transition system and a notion of strong bisimulation, both of which are expounded in detail in a companion paper. We also report briefly on workinprogress based upon the corresponding notion of weak bisimulation, in which internal actions cannot be observed.
Bigraphs and Mobile Processes (revised)
, 2004
"... A bigraphical reactive system (BRS) involves bigraphs, in which the nesting of nodes represents locality, independently of the edges connecting them; it also allows bigraphs to reconfigure themselves. BRSs aim to provide a uniform way to model spatially distributed systems that both compute and comm ..."
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Cited by 66 (7 self)
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A bigraphical reactive system (BRS) involves bigraphs, in which the nesting of nodes represents locality, independently of the edges connecting them; it also allows bigraphs to reconfigure themselves. BRSs aim to provide a uniform way to model spatially distributed systems that both compute and communicate. In this memorandum we develop their static and dynamic theory. In Part I we illustrate...
Transition systems, link graphs and Petri nets
, 2004
"... A framework is defined within which reactive systems can be studied formally. The framework is based upon scategories, a new variety of categories, within which reactive systems can be set up in such a way that labelled transition systems can be uniformly extracted. These lead in turn to behavi ..."
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Cited by 29 (5 self)
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A framework is defined within which reactive systems can be studied formally. The framework is based upon scategories, a new variety of categories, within which reactive systems can be set up in such a way that labelled transition systems can be uniformly extracted. These lead in turn to behavioural preorders and equivalences, such as the failures preorder (treated elsewhere) and bisimilarity, which are guaranteed to be congruential. The theory rests upon the notion of relative pushout previously introduced by the authors. The framework
Presheaf Models for the piCalculus
, 1997
"... Recent work has shown that presheaf categories provide a general model of concurrency, with an inbuilt notion of bisimulation based on open maps. Here it is shown how this approach can also handle systems where the language of actions may change dynamically as a process evolves. The example is the p ..."
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Cited by 19 (4 self)
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Recent work has shown that presheaf categories provide a general model of concurrency, with an inbuilt notion of bisimulation based on open maps. Here it is shown how this approach can also handle systems where the language of actions may change dynamically as a process evolves. The example is the picalculus, a calculus for `mobile processes' whose communication topology varies as channels are created and discarded. A denotational semantics is described for the picalculus within an indexed category of profunctors; the model is fully abstract for bisimilarity, in the sense that bisimulation in the model, obtained from open maps, coincides with the usual bisimulation obtained from the operational semantics of the picalculus. While attention is concentrated on the `late' semantics of the picalculus, it is indicated how the `early' and other variants can also be captured.
A Distributed PiCalculus with Local Areas of Communication
 in: High Level Concurrent Languages
, 2001
"... This paper introduces a process calculus designed to capture the phenomenon of names which are known universally but always refer to local information. Our system extends the picalculus so that a channel name can have within its scope several disjoint local areas. Such a channel name may be used fo ..."
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Cited by 6 (0 self)
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This paper introduces a process calculus designed to capture the phenomenon of names which are known universally but always refer to local information. Our system extends the picalculus so that a channel name can have within its scope several disjoint local areas. Such a channel name may be used for communication within an area, it may be sent between areas, but it cannot itself be used to transmit information from one area to another. Areas are arranged in a hierarchy of levels, distinguishing for example between a single application, a machine, or a whole network. We give an operational semantics for the calculus, and develop a type system that guarantees the proper use of channels within their local areas. We illustrate with models of an internet service protocol and a pair of distributed agents.
Encoding Distributed Areas and Local Communication into the πCalculus
, 2002
"... We show how the #calculus can express local communications within a distributed system, through an encoding of the local area #calculus, an enriched system that explicitly represents names which are known universally but always refer to local information. Our translation replaces pointtopoint co ..."
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Cited by 4 (0 self)
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We show how the #calculus can express local communications within a distributed system, through an encoding of the local area #calculus, an enriched system that explicitly represents names which are known universally but always refer to local information. Our translation replaces pointtopoint communication with a system of shared local ethers; we prove that this preserves and reflects process behaviour.
Cut Reduction in Linear Logic as Asynchronous SessionTyped Communication ∗
"... Prior work has shown that intuitionistic linear logic can be seen as a sessiontype discipline for the πcalculus, where cut reduction in the sequent calculus corresponds to synchronous process reductions. In this paper, we exhibit a new process assignment from the asynchronous, polyadic πcalculus ..."
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Cited by 2 (2 self)
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Prior work has shown that intuitionistic linear logic can be seen as a sessiontype discipline for the πcalculus, where cut reduction in the sequent calculus corresponds to synchronous process reductions. In this paper, we exhibit a new process assignment from the asynchronous, polyadic πcalculus to exactly the same proof rules. Prooftheoretically, the difference between these interpretations can be understood through permutations of inference rules that preserve observational equivalence of closed processes in the synchronous case. We also show that, under this new asynchronous interpretation, cut reductions correspond to a natural asynchronous buffered session semantics, where each session is allocated a separate communication buffer.
On the Expressive Power of Polyadic . . .
 ELECTRONIC NOTES IN THEORETICAL COMPUTER SCIENCE
, 2002
"... We extend the #calculus with polyadic synchronisation, a generalisation of the communication mechanism which allows channel names to be composite. We show that this operator embeds nicely in the theory of #calculus, and makes it possible to derive divergencefree encodings of distributed calculi. ..."
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We extend the #calculus with polyadic synchronisation, a generalisation of the communication mechanism which allows channel names to be composite. We show that this operator embeds nicely in the theory of #calculus, and makes it possible to derive divergencefree encodings of distributed calculi. We give a separation result between the #calculus with polyadic synchronisation ( #) and the original calculus, in the style of an analogous result given by Palamidessi for mixed choice. We encode Local Area # showing how to control the local use of resources in #.
Static Control of Code Migration
"... This paper presents a type system to control the migration of code between sites in a concurrent distributed framework. The type system constitutes a decidable mechanism to ensure specific security policies, which control remote communication, process migration, and channel creation. The approach ..."
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This paper presents a type system to control the migration of code between sites in a concurrent distributed framework. The type system constitutes a decidable mechanism to ensure specific security policies, which control remote communication, process migration, and channel creation. The approach is as follows: each network administrator specifies sites privileges, and a type system checks that the processes running at those sites, as well as the composition of the sites, respect these policies. At runtime, welltyped networks do not violate the security policies declared for each site.
This document in subdirectoryRS/97/34/ Presheaf Models for the πCalculus
, 1997
"... Reproduction of all or part of this work is permitted for educational or research use on condition that this copyright notice is included in any copy. See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting: BRICS ..."
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Reproduction of all or part of this work is permitted for educational or research use on condition that this copyright notice is included in any copy. See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting: BRICS