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An Object Calculus for Asynchronous Communication
 Proceedings of the European Conference on ObjectOriented Programming (ECOOP
, 1991
"... This paper presents a formal system based on the notion of objects and asynchronous communication. Built on Milner's work on ßcalculus, the communication primitive of the formal system is purely asynchronous, which makes it unique among various concurrency formalisms. Computationally this results i ..."
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Cited by 363 (29 self)
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This paper presents a formal system based on the notion of objects and asynchronous communication. Built on Milner's work on ßcalculus, the communication primitive of the formal system is purely asynchronous, which makes it unique among various concurrency formalisms. Computationally this results in a consistent reduction of Milner's calculus, while retaining the same expressive power. Seen semantically asynchronous communication induces a surprisingly different framework where bisimulation is strictly more general than its synchronous counterpart. This paper shows basic construction of the formal system along with several illustrative examples. 1 Introduction The formal system introduced in this paper is intended to accomplish two purposes. First, it provides a simple and rigorous formalism which encapsulates essential features of concurrent objectorientation [26, 25]. Being successful as a programming methodology for dynamic concurrent computing, its theoretical contents are far f...
A Calculus of Mobile Processes, Part I
 I AND II. INFORMATION AND COMPUTATION
, 1989
"... We present the ßcalculus, 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 189 (3 self)
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We present the ßcalculus, 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 ßcalculus 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 ßcalculus generalises conventional process algebras in treating mobility, several examples exploiting mobility are given in some detail. The important examples are the encoding into the ß calculus of higherorder functions (the calculus and combinatory algebra), the tr...
The Fusion Calculus: Expressiveness and Symmetry in Mobile Processes (Extended Abstract)
 LICS'98
, 1998
"... We present the fusion calculus as a significant step towards a canonical calculus of concurrency. It simplifies and extends the πcalculus.
The fusion calculus contains the polyadic πcalculus as a proper subcalculus and thus inherits all its expressive power. The gain is that fusion contains action ..."
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Cited by 108 (13 self)
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We present the fusion calculus as a significant step towards a canonical calculus of concurrency. It simplifies and extends the πcalculus.
The fusion calculus contains the polyadic πcalculus as a proper subcalculus and thus inherits all its expressive power. The gain is that fusion contains actions akin to updating a shared state, and a scoping construct for bounding their effects. Therefore it is easier to represent computational models such as concurrent constraints formalisms. It is also easy to represent the so called strong reduction strategies in the lambdacalculus, involving reduction under abstraction. In the πcalculus these tasks require elaborate encodings.
The dramatic main point of this paper is that we achieve these improvements by simplifying the πcalculus rather than adding features to it. The fusion calculus has only one binding operator where the πcalculus has two (input and restriction). It has a complete symmetry between input and output actions where the πcalculus has not. There is only one sensible variety of bisimulation congruence where the picalculus has at least three (early, late and open). Proofs about the fusion calculus, for example in complete axiomatizations and full abstraction, therefore are shorter and clearer.
Our results on the fusion calculus in this paper are the following. We give a structured operational semantics in the traditional style. The novelty lies in a new kind of action, fusion actions for emulating updates of a shared state. We prove that the calculus contains the πcalculus as a subcalculus. We define and motivate the bisimulation equivalence and prove a simple characterization of its induced congruence, which is given two versions of a complete axiomatization for finite terms. The expressive power of the calculus is demonstrated by giving a straightforward encoding of the strong lazy lambdacalculus, which admits reduction under lambda abstraction.
Bisimulation for higherorder process calculi
 INFORMATION AND COMPUTATION
, 1996
"... A higherorder process calculus is a calculus for communicating systems which contains higherorder constructs like communication of terms. We analyse the notion of bisimulation in these calculi. We argue that both the standard definition of bisimulation (i.e., the one for CCS and related calculi), ..."
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Cited by 62 (5 self)
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A higherorder process calculus is a calculus for communicating systems which contains higherorder constructs like communication of terms. We analyse the notion of bisimulation in these calculi. We argue that both the standard definition of bisimulation (i.e., the one for CCS and related calculi), as well as higherorder bisimulation [E. Astesiano,
Towards an Object Calculus
, 1991
"... The development of concurrent objectbased programmig languages has suffered from the lack of any generally accepted formal foun ion for de finn their semantics. Furthermore, the delicate relation p between objectoriented features supportin reuse an operation features con n g in teraction a n state ..."
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Cited by 47 (8 self)
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The development of concurrent objectbased programmig languages has suffered from the lack of any generally accepted formal foun ion for de finn their semantics. Furthermore, the delicate relation p between objectoriented features supportin reuse an operation features con n g in teraction a n state chan is poorlyun rstood in a con urren t settin To address this problem, we propose the developmen t of an object calculus, borrowi n heavily from relevan t work in the area of process calculi. To this en we briefly review some of this work, we pose some i ormal requiremen ts for an object calculus, an we present the syntax, operation seman tics an use through examples of a proposed object calculus, called OC.
Functional Nets
 IN PROC. EUROPEAN SYMPOSIUM ON PROGRAMMING, NUMBER 1782 IN LNCS
, 2000
"... Functional nets combine key ideas of functional programming and Petri nets to yield a simple and general programming notation. They ..."
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Cited by 34 (5 self)
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Functional nets combine key ideas of functional programming and Petri nets to yield a simple and general programming notation. They
Relational Reasoning about Functions and Nondeterminism
, 1998
"... 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 Dissertation Series publications. Copies may be obtained by contacting: BRICS ..."
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Cited by 31 (4 self)
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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 Dissertation Series publications. Copies may be obtained by contacting: BRICS
HigherOrder, Linear, Concurrent Constraint Programming
, 1992
"... We present a very simple and powerful framework for indeterminate, asynchronous, higherorder computation based on the formulaasagent and proofascomputation interpretation of (higherorder) linear logic [Gir87]. The framework significantly refines and extends the scope of the concurrent constrai ..."
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Cited by 30 (5 self)
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We present a very simple and powerful framework for indeterminate, asynchronous, higherorder computation based on the formulaasagent and proofascomputation interpretation of (higherorder) linear logic [Gir87]. The framework significantly refines and extends the scope of the concurrent constraint programming paradigm [Sar89] in two fundamental ways: (1) by allowing for the consumption of information by agents it permits a direct modelling of (indeterminate) state change in a logical framework, and (2) by admitting simplytyped terms as dataobjects, it permits the construction, transmission and application of (abstractions of) programs at runtime. Much more dramatically, however, the framework can be seen as presenting higherorder (and if desired, constraintenriched) versions of a variety of other asynchronous concurrent systems, including the asynchronous ("input guarded") fragment of the (firstorder) ßcalculus, Hewitt's actors formalism, (abstract forms of) Gelernter's Lin...
Beyond Digital Naturalism
, 1994
"... The success of Artificial Life depends on whether it will help solving the conceptual problems of biology. Biology may be viewed as the science of the transformation of organizations. And, yet, biology lacks a theory of organization. We use this as an example of the challenge that Artificial Life mu ..."
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Cited by 29 (1 self)
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The success of Artificial Life depends on whether it will help solving the conceptual problems of biology. Biology may be viewed as the science of the transformation of organizations. And, yet, biology lacks a theory of organization. We use this as an example of the challenge that Artificial Life must meet. "If  as I believe  physics and chemistry are conceptually inadequate as a theoretical framework for biology, it is because they lack the concept of function, and hence that of organization. [...] [P]erhaps, therefore, we should give the [...] computer scientists more of a say in the formulation of Theoretical Biology."  Christopher LonguetHiggins, 1969 [29] 1 Life and the organization problem in biology There are two readings of "life": "life" as an embodied phenomenon and "life" as a concept. Foucault [20] points out that up to the end of the eighteenth century life does not exist: only living beings. Living beings are but a class in the series of all things in the world. T...