This book constitutes the refereed proceedings of the 10th International Conference of Z Users, ZUM'97, held in Reading, UK, in April 1997. The volume presents 18 revised full papers together with three invited presentations by internationally leading experts. The papers are organized into topical sections on real-time systems, tools, logic, system development, reactive systems, refinement, and applications. Also a select Z bibliography by Jonathan Bowen is added. All in all, the book competently reports the state-of-the-art in research and advanced applications of the Z notation.

1 In a number of recent presentations – most notably at FME’96 –oneofthe foremost scientists in the ?eld of formal methods, C.A.R. Hoare,has highlighted the fact that formal methods are not the only technique for producing reliable software. This seems to have caused some controversy,not least amongst formal methods practitioners. How can one of the founding fathers of formal methods seemingly denounce the ?eld of research after over a quarter of a century of support? This is a question that has been posed recently by some formal methods skeptics. However, Prof. Hoare has not abandoned formal methods. He is reiterating, 2 albeitmoreradically,his1987view thatmorethanonetoolandnotationwillbe requiredinthepractical,industrialdevelopmentoflarge-scalecomplexcomputer systems; and not all of these tools and notations will be, or even need be, formal in nature. Formalmethods arenotasolution,butratheroneofaselectionoftechniques that have proven to be useful in the development of reliable complex systems, and to result in hardware and software systems that can be produced on-time and within a budget, while satisfying the stated requirements. After almostthree decades,the time has come to view formalmethods in the context of overall industrial-scale system development, and their relationship to othertechniquesandmethods.Weshouldnolongerconsidertheissueofwhether we are “pro-formal” or “anti-formal”, but rather the degree of formality (if any) that we need to support in system development. This is a goal of ZUM’98, the 11th International Conference of Z Users, held for the ?rst time within continental Europe in the city of Berlin, Germany.

This volume contains the proceedings of MPC 2000, the ?fth international c- ference on Mathematics of Program Construction. This series of conferences aims to promote the development of mathematical principles and techniques that are demonstrably useful and usable in the process of constructing c- puter programs (whether implemented in hardware or software). The focus is on techniques that combine precision with concision, enabling programs to be constructed by formal calculation. Within this theme, the scope of the series is very diverse, including programming methodology, program speci?cation and transformation, programming paradigms, programming calculi, and progr- ming language semantics. The quality of the papers submitted to the conference was in general very high. However,the number of submissions has decreased compared to the pre- ous conferences in the series. Each paper was refereed by at least ?ve and often more committee members. In order to maintain the high standards of the c- ference the committee took a stringent view on quality; this has meant that, in some cases, a paper was rejected even though there was a basis for a good c- ference or journal paper but the submitted paper did not meet the committee’s required standards. In a few cases a good paper was rejected on the grounds that it did not ?t within the scope of the conference.

The European Commission emphasizes, in its Fifth Research Framework, the “. . . emerging generic dependability requirements in the information society, stemming both from the ubiquity and volume of embedded and networked systems and services as well as from the global and complex nature of large scale information and communication infrastructures, from citizens, administrations and business in terms of technologies, tools, systems, applications and services". The series of Conference on Computer Safety, Reliability, and Security (Safecomp) contributes to satisfy these requirements by reviewing the state of the art, experiences, and new trends in the relevant scientific and industrial areas. Safecomp is intended to be a platform for technology transfer among academia, industry, and research institutions, providing the opportunity for exchange of ideas, opinions, and visions among experts. This year Safecomp celebrates the 20th anniversary, its first Conference having been organized in Stuttgart by EWICS (European Workshop on Industrial Computer Systems) in 1979, and we hope these Proceedings will contribute to the celebration by supporting Safecomp aims. The Proceedings include the 25 papers that have been presented orally at the Conference and the full version of the 14 papers that have been presented as posters, all of which were selected from 76 submissions. Papers almost uniformly take up Safecomp topics, dealing with the issues of Safety Assessment and Human Factors, Verification and Validation, Design for Safety, Formal Methods, and Security.

Industrial Strength Formal Methods in Practice provides hands-on experience and guidance for anyone who needs to apply formal methods successfully in an industrial context. Each chapter is written by an expert in software engineering or formal methods, and contains background information, introductions to the techniques being used, actual fragments of formalised components, details of results and an analysis of the overall approach. It provides specific details on how to produce high-quality software that comes in on-time and within budget. Aimed mainly at practitioners in software engineering and formal methods, this book will also be of interest to the following groups; academic researchers working in formal methods who are interested in evidence of their success and in how they can be applied on an industrial scale, and students on advanced software engineering courses who need real-life specifications and examples on which to base their work.

An increasing recognition of the role of the human-system interface is leading to new extensions and styles of specification. Techniques are being developed that facilitate the expression of user-oriented requirements and the refinement and checking of specifications of interactive systems. This book reflects the state of the art in this important area and also contains a summary of working group discussions about how the various techniques represented might be applied to a common case study.

Formal methods have been established as the rigorous engineering methodology for the system development. Applying formal methods to a large and complex system development often requires the modelling of different aspects of such a system. For instance, complex systems (such as integrated avionics systems, engine control software) can involve functional and timing requirements that must be eventually implemented as executing code on a communicating distributed topology. This book contains the papers presented at the First International Workshop on Integrated Formal Methods, held at the University of York in June 1999. The conference provided a forum for the discussion of theoretical aspects of combing behavioural and state-based formalisms and practical solutions to the industrial problems of this approach.

Increasing the designer’s con dence that a piece of software or hardwareis c- pliant with its speci cation has become a key objective in the design process for software and hardware systems. Many approaches to reaching this goal have been developed, including rigorous speci cation, formal veri cation, automated validation, and testing. Finite-state model checking, as it is supported by the explicit-state model checkerSPIN,is enjoying a constantly increasingpopularity in automated property validation of concurrent, message based systems. SPIN has been in large parts implemented and is being maintained by Gerard Ho- mann, and is freely available via ftp fromnetlib.bell-labs.comor from URL http://cm.bell-labs.com/cm/cs/what/spin/Man/README.html. The beauty of nite-state model checking lies in the possibility of building \push-button" validation tools. When the state space is nite, the state-space traversal will eventually terminate with a de nite verdict on the property that is being validated. Equally helpful is the fact that in case the property is inv- idated the model checker will return a counterexample, a feature that greatly facilitates fault identi cation. On the downside, the time it takes to obtain a verdict may be very long if the state space is large and the type of properties that can be validated is restricted to a logic of rather limited expressiveness.

Formal Methods for Open Object-Based Distributed Systems IV presents the leading edge in the fields of object-oriented programming, open distributed systems, and formal methods for object-oriented systems. With increased support within industry regarding these areas, this book captures the most up-to-date information on the subject. Papers in this volume focus on the following specific technologies: components; mobile code; Java®; The Unified Modeling Language (UML); refinement of specifications; types and subtyping; temporal and probabilistic systems. This volume comprises the proceedings of the Fourth International Workshop on Formal Methods for Open Object-Based Distributed Systems (FMOODS 2000), which was sponsored by the International Federation for Information Processing (IFIP) and held in Stanford, California, USA, in September 2000.