Data Refinement

The goal of this book is to provide a comprehensive and systematic introduction to the important and highly applicable method of data refinement and the simulation methods used for proving its correctness. The authors concentrate in the first part on the general principles needed to prove data refinement correct. They begin with an explanation of the fundamental notions, showing that data refinement proofs reduce to proving simulation. The book's second part contains a detailed survey of important methods in this field, which are carefully analysed, and shown to be either incomplete, with counterexamples to their application, or to be always applicable whenever data refinement holds. This is shown by proving, for the first time, that all these methods can be described and analysed in terms of two simple notions: forward and backward simulation. The book is self-contained, going from advanced undergraduate level and taking the reader to the state of the art in methods for proving simulation.

The Sixth Refinement Workshop took place at City University in London from 5th to 7th January 1994. The present volume includes all of the papers which were submitted and accepted for presentation, together with two papers by invited speakers. The workshops in the series have generally occurred at one year intervals but in this last case a two year period had elapsed. These workshops have established themselves as an important event in the calendar for all those who are interested in progress in the underlying theory of refinement and in the take-up by industry of the methods supported by that theory. One of the proposed themes of the sixth workshop was the reporting of successful adoption in industry of rigorous software development methods. The programme committee was perhaps slightly disappointed by the response from industry to the call in this respect. However, the recent period could be characterised as one of consolidation, when those companies which have made the decision that formal development methods are important to their business have been adopting them where appropriate and finding them to be worthwhile. On the other hand,. the difficult economic climate which exists in most parts of the developed world is perhaps not the context within which companies still dubious about the benefits are goil'\g to opt for making major changes in their working practices.

The stepwise refinement method postulates a system construction route that starts with a high-level specification, goes through a number of provably correct development steps, and ends with an executable program. The contributions to this volume survey the state of the art in this extremely active research area. The world's leading specialists in concurrent program specification, verification, and the theory of their refinement present latest research results and surveys of the fields. State-based, algebraic, temporal logic oriented and category theory oriented approaches are presented. Special attention is paid to the relationship between compositionality and refinement for distributed programs. Surveys are given of results on refinement in partial-order based approaches to concurrency. A unified treatment is given of the assumption/commitment paradigm in compositional concurrent program specification and verification, and the extension of these to liveness properties. Latest results are presented on specifying and proving concurrent data bases correct, and deriving network protocols from their specifications.

Refinement is one of the cornerstones of the formal approach to software engineering, and its use in various domains has led to research on new applications and generalisation. This book brings together this important research in one volume, with the addition of examples drawn from different application areas. It covers four main themes: Data refinement and its application to Z Generalisations of refinement that change the interface and atomicity of operations Refinement in Object-Z Modelling state and behaviour by combining Object-Z with CSP Refinement in Z and Object-Z: Foundations and Advanced Applications provides an invaluable overview of recent research for academic and industrial researchers, lecturers teaching formal specification and development, industrial practitioners using formal methods in their work, and postgraduate and advanced undergraduate students. This second edition is a comprehensive update to the first and includes the following new material: Early chapters have been extended to also include trace refinement, based directly on partial relations rather than through totalisation Provides an updated discussion on divergence, non-atomic refinements and approximate refinement Includes a discussion of the differing semantics of operations and outputs and how they affect the abstraction of models written using Object-Z and CSP Presents a fuller account of the relationship between relational refinement and various models of refinement in CSP Bibliographic notes at the end of each chapter have been extended with the most up to date citations and research

Refinement is one of the cornerstones of a formal approach to software engineering. Refinement is all about turning an abstract description (of a soft or hardware system) into something closer to implementation. It provides that essential bridge between higher level requirements and an implementation of those requirements. This book provides a comprehensive introduction to refinement for the researcher or graduate student. It introduces refinement in different semantic models, and shows how refinement is defined and used within some of the major formal methods and languages in use today. It (1) introduces the reader to different ways of looking at refinement, relating refinement to observations(2) shows how these are realised in different semantic models (3) shows how different formal methods use different models of refinement, and (4) how these models of refinement are related.

Illustrates by example the typical steps necessary in computer science to build a mathematical model of any programming paradigm . Presents results of a large and integrated body of research in the area of 'quantitative' program logics.

Refinement is the term used to describe systematic and formal methods of specifying hard- and software and transforming the specifications into designs and implementations. The value of formal methods in producing reliable hard- and software is widely appreciated by academics and workers in industry, despite the fact that certain research areas, such as the application to industrial-scale problems, are still in their infancy. This volume contains the papers presented at the 5th Refinement Workshop held in London, 8-10 January 1992. Its theme was the theory and practice of software specifications, which is the transformation of formal software specifications into more correct specifications, designs and codes. This has been an important area of research for the last 5 years and the workshop addressed specific issues and problems related to it. Among the topics discussed in this volume are: the role of refinement in software development, parallel designs and implementations, methods and tools for verification of critical properties, refinement and confidentiality, concurrent processes as objects, the compliance of Ada programs with Z specifications and a tactic driven refinement tool. This is the latest refinement workshop proceedings to be published in the Workshops in Computing series (the 3rd and 4th workshops having appeared in 1990 and 1991 respectively). It will be of interest to academic and industrial researchers, postgraduate students and research-oriented developers in the computer industry.

On the Refinement Calculus gives one view of the development of the refinement calculus and its attempt to bring together - among other things - Z specifications and Dijkstra's programming language. It is an excellent source of reference material for all those seeking the background and mathematical underpinnings of the refinement calculus.