Join-calculus

Abstract: We present the a-calculus, 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 rr-calculus 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 n-calculus generalises conventional process algebras in treating mobility, several examples exploiting mobility are given in some detail. The important examples are the encoding into the n-calculus of higher-order functions (the I-calculus 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 distinctions-i.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 work-in-progress based upon the corresponding notion of weak bisimulation, in which internal actions cannot be observed. 0 1992 Academic Press, Inc.

Abstract: This paper considers how locality restrictions on the use of capabilities can be enforced by a static type system. A distributed π-calculus with a simple reduction semantics is introduced, integrating location and migration primitives from the Distributed Join Calculus with asynchronous π communication. It is given a type system in which the input and output capabilities of channels may be either global, local or absent. This allows compile-time optimization where possible but retains the expressiveness of channel communication. Subtyping allows all communications to be invoked uniformly. We show that the most local possible capabilities for internal channels can be inferred automatically.

Abstract: We present a first distributed implementation of the Cardelli-Gordon's ambient calculus. We use Jocaml as an implementation language and we present a formal translation of Ambients into the distributed join calculus, the process calculus associated with Jocaml. We prove the correctness of the translation.

Abstract: Functional nets combine key ideas of functional programming and Petri nets to yield a simple and general programming notation. They have their theoretical foundation in Join calculus. This paper gives an overview of functional nets as a kernel programming language, it presents an object-based version of Join calculus, and it shows how the two relate.