Guest editorial

This issue of Concurrency and Computation: Practice and Experience is devoted to extended versions of selected contributions from Communicating Process Architectures (CPA) 2007. CPA 2007 was held at the University of Surrey, U.K., in July 2007, and the papers presented here were selected both from refereed technical sessions and invited speakers. CPA 2007 was the 30th meeting of a long and distinguished conference series that has always been interested in relating theoretical aspects of concurrency to practical programming aspects of concurrent systems. The series began with life as the occamUser Group, and evolved into its current form via several other titles. The very first meeting was a single day workshop organized by Inmos in 1985. The main topic for discussion back then was the Transputer, and over time, the interests central to the conference have reflected the hot topics in practical implementations of theoretical approaches to concurrency—both hardware and software. As the conference series evolved, so have the interests: today these include formal approaches to program derivation, programming languages incorporating -calculus models of mobility, Java libraries offering Communicating Sequential Process (CSP)-style language primitives, and multi-core processors. While being proud of its theoretical roots, the conference series has always maintained a practical viewpoint—reflected in the strong industrial interest in the series. Industrial sponsorship and support has come from companies such as Philips, Formal Systems Europe LTD, and Celoxica. In 2007, the conference received significant support from AWE U.K. The Programme and Reviewing Committee consisted of 46 members from eight different countries. Each submission was evaluated and reviewed by three members of the committee, and reports were submitted to the Editorial Board for discussion and programme selection. Twenty-eight papers were selected for publication in the conference proceedings (as well as two invited papers). After the conference, the authors were invited to submit extended versions of their papers for inclusion in this special issue. After additional refereeing and discussion, we were able to accept nine papers for publication in this special issue. Fine-grain concurrency: Sir Tony Hoare is synonymous with much of what we appreciate as modern-day Computer Science. His CSP is one of the most widely studied theoretical models of concurrent systems and forms the inspiration for much of the CPA conference series. In this paper he considers fine-grained approaches to concurrency—those that may not have such explicit interactions between processes—such as interleaving threads and possibly even shared memory. A simple theory, combining the merits of a number of different theories, is presented. The paper is considered as on-going research, but represents the first model of this theory.