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.

A calculus of mobile processes, II

An Introduction to MultiAgent Systems.

From the Publisher:
Since the introduction of Hoares' Communicating Sequential Processes notation, powerful new tools have transformed CSP into a practical way of describing industrial-sized problems. This book gives you the fundamental grasp of CSP concepts you'll need to take advantage of those tools.Part I provides a detailed foundation for working with CSP, using as little mathematics as possible. It introduces the ideas behind operational, denotational and algebraic models of CSP. Parts II and III go into greater detail about theory and practice. Topics include: parallel operators, hiding and renaming, piping and enslavement, buffers and communication, termination and sequencing, and semantic theory. Three detailed practical case studies are also presented.For anyone interested in modeling sequential processes.

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The Theory and Practice of Concurrency

Publisher Summary
This chapter focuses on rewrite systems, which are directed equations used to compute by repeatedly replacing sub-terms of a given formula with equal terms until the simplest form possible is obtained. As a formalism, rewrite systems have the full power of Turing machines and may be thought of as nondeterministic Markov algorithms over terms rather than strings. The theory of rewriting is in essence a theory of normal forms. To some extent, it is an outgrowth of the study of A. Church's Lambda Calculus and H. B. Curry's Combinatory Logic. The chapter discusses the syntax and semantics of equations from the algebraic, logical, and operational points of view. To use a rewrite system as a decision procedure, it must be convergent. The chapter describes this fundamental concept as an abstract property of binary relations. To use a rewrite system for computation or as a decision procedure for validity of identities, the termination property is crucial. The chapter presents the basic methods for proving termination. The chapter discusses the question of satisfiability of equations and the convergence property applied to rewriting.

CHAPTER 6 – Rewrite Systems

We survey the literature available on the topic of domain-specific languages as used for the construction and maintenance of software systems. We list a selection of 75 key publications in the area, and provide a summary for each of the papers. Moreover, we discuss terminology, risks and benefits, example domain-specific languages, design methodologies, and implementation techniques.

https://people.cis.ksu.edu/~schmidt/505f14/Lectures/DSLbib.pdf

Domain-specific languages: an annotated bibliography

A grid protocol models concurrent computation, and consists of one or more modules repeatedly performing parallel I/O and computation. We provide several concise specification formats and correctness results on (external) I/O behaviour, and illustrate our approach by examples. Note: Some of the results described in this paper were published earlier in [BHP97]; other results were established by students in the '96/'97 course Process Algebra II delivered at the University of Amsterdam [BJM97], and in a master's thesis [Pou97].

Grid Protocol Specifications

For money-like informational commodities the notions of architectural adequacy and evolutionary adequacy are proposed as the first two stages of a moneyness maturity hierarchy. Then three classes of informational commodities are distinguished: exclusively informational commodities, strictly informational commodities, and ownable informational commodities. For each class money-like instances of that commodity class, as well as monies of that class may exist. With the help of these classifications and making use of previous assessments of Bitcoin, it is argued that at this stage Bitcoin is unlikely ever to evolve into a money. Assessing the evolutionary adequacy of Bitcoin is perceived in terms of a search through its design hull for superior design alternatives. An extensive comparison is made between the search for superior design alternatives to Bitcoin and the search for design alternatives to a specific and unconventional view on the definition of fractions.

/pdf/architectural-adequacy-and-evolutionary-adequacy-as-pvy9dgj1i5.pdf

Architectural Adequacy and Evolutionary Adequacy as Characteristics of a Candidate Informational Money

Multi-threading allows agents to pursue a heterogeneous collection of tasks in an orderly manner. The view of multi-threading that emerges from thread algebra is applied to the case where a single agent, who may be human, maintains a hierarchical multithread as an architecture of its own activities.

/pdf/personal-multi-threading-ldg8ndc6hp.pdf

Personal Multi-threading

Outsourcing, the passing on of tasks by organizations to other organizations, often including the personnel and means to perform these tasks, has become an important IT-business strategy over the past decades. We investigate imaginative definitions for outsourcing relations and outsourcing transformations. Abstract models of an extreme and unrealistic simplicity are considered in order to investigate possible definitions of outsourcing. Rather than covering all relevant practical cases an imaginative definition of a concept provides obvious cases of its instantiation from which more refined or liberal definitions may be derived. A definition of outsourcing induces to a complementary definition of insourcing. Outsourcing and insourcing have more complex variations in which multiple parties are involved. All of these terms both refer to state transformations and to state descriptions pertaining to the state obtained after such transformations. We make an attempt to disambiguate the terminology in that respect and we make an attempt to characterize the general concept of sourcing which captures some representative cases. Because mereology is the most general theory of parthood relations we coin business mereology as the general theory in business studies which concerns the full variety of sourcing relations and transformations.

/pdf/business-mereology-imaginative-definitions-of-insourcing-and-n3z08zrbyn.pdf

Business mereology: imaginative definitions of insourcing and outsourcing transformations

Machine functions have been introduced by Earley and Sturgis
in [6] in order to provide a mathematical foundation of the use of the
T-diagrams proposed by Bratman in [5]. Machine functions describe the
operation of a machine at a very abstract level. A theory of hardware and
software based on machine functions may be called a machine function
theory, or alternatively when focusing on inputs and outputs for machine
functions a control code algebra (CCA). In this paper we develop some
control code algebras from first principles. Machine function types are
designed specifically for various application such as program compilation,
assembly, interpretation, managed interpretation and just-in-time compilation.
Machine function dependent CCA’s are used to formalize the
well-known compiler fixed point, the managed execution of JIT compiled
text and the concept of a verifying compiler.

Jan A. Bergstra

Papers

Grid Protocol Specifications

Architectural Adequacy and Evolutionary Adequacy as Characteristics of a Candidate Informational Money

Personal Multi-threading

Business mereology: imaginative definitions of insourcing and outsourcing transformations

Machine function based control code algebras