This volume constitutes the proceedings of the International Symposium on Design and Implementation of Symbolic Computation Systems (DISCO '93), held in Gmunden, Austria, in September 1993. The growing importance of systems for symbolic computation has greatly influenced the decision of organizing this third conference in the series: DISCO '93 focuses mainly on the most innovative methodological and technological aspects of the design and implementation of hardware and software systems for symbolic and algebraic computation, automated reasoning, geometric modeling and computation, and automatic programming. The general objective of DISCO '93 is to present an up-to-date view of the field and to serve as a forum insymbolic computation for the scientific exchange among academic, industrial and user communities. Besides invited talks by Buchberger, Monagan, Omodeo and Hong, the volume contains 28 contributions, carefully selected by a highly competent international program committee from a total of 56 submissions.

This book presents a collection of coordinated scientific papers describing the work conducted and the results achieved within the LOGIDATA+ project, a research action funded by the Italian national research council CNR. Theaim of the LOGIDATA+ project is the definition of advanced database systems which significantly extend the functionalities of the current systems, with specific reference to the application areas for which relational systemsare not considered satisfactory. These new systems will allow the definitionof data with complex structures, the representation of semantic relationships between objects, and the use of powerful query and update languages. They will be based on a combination of techniques originatingfrom relational databases and logic programming, with contributions from object-oriented programming. The goal of the LOGIDATA+ project is the design, definition, and prototype implementation of a database management system with complex structures and a class hierarchy, to be accessed through a rule-based language. This book presents an integrated view of the project at the end of the first phase. The second phase will be mainly concerned with the implementation of prototypes.

DISCO 92 was held on the Newton Park campus of Bath College of Higher Education, England, April 13-15, 1992. Beside the formal lectures dedicated to design and implementation issues of computer algebra, there were several software demonstrations and an opportunity for system designers to compare systems. This volume presents the proceedings of the conference. It contains 18 papers on a variety of design and implementation issues. One general theme which clearly emerges is the need for interconnections between systems, as no one systems incorporates all the facilities that users want. Various effortsare being made to design such links, but generally in limited contexts (suchas the Maple project or the Posso project).

As computer technology is used to control critical systems to an increasing degree, it is vital that the methods for developing and understanding these systems are substantially improved. The mathematical and scientific foundations currently used are extremely limited which means that their correctness and reliability cannot be ensured to an acceptable level. Systems engineering needs to become a fully fledged scientific discipline and formal methods, which are characterised by their firm mathematical foundations, are playing a vital role in achieving this transition. This volume is based on the proceedings of the Formal Methods Workshop (FM91), held in Drymen, Scotland, 24-27 September 1991. This was the second workshop sponsored by the Canadian and US governments to address the role of formal methods in the development of digital systems. Traditionally, formal methods have evolved in isolation from more conventional approaches, and one of the aims of this workshop was to emphasise the benefits of integrating the two areas. The workshop concentrated on the themes of quality assurance, design methods and mathematical modelling techniques. Particular emphasis was given to safety and security applications. Among the topics covered in this volume are: what is a formal method?; social research on formal methods; current quality assurance methods and formal methods; a pragmatic approach to validation; integrating methods in practice; composition of descriptions; and topics in large program formal development. Formal Methods in Systems Engineering provides an overview of many of the major approaches to formal methods and the benefits which can result from them. It is relevant to academic and industrial researchers, industrial practitioners and government workers with an interest in certification.

This volume presents the proceedings of the fifth Conference on Advanced Information Systems Engineering, CAiSE '93, held at the University of Paris-Sorbonne in June 1993. Initiated by J. Bubenko from the Swedish Institute for Systems Development in Stockhom, Sweden, and A. Solvberg from the Norwegian Institute of Technology in Trondheim, Norway, this series of conferences evolved from a Nordic audience to a truly European one. All the conferences have attracted international papers of high quality, indicating the needfor an international conference on advanced information systems engineering topics. The spectrum of contributions contained in the present proceedings extends from inevitable and still controversial issues regarding modeling of information systems, via development environments and experiences, to various novel views forsome specific aspects of information systems development such as reuse, schema integration, and evolution.

Enterprise operation efficiency is seriously constrained by the inability to provide the right information, in the right place, at the right time. In spite of significant advances in technology it is still difficult to access information used or produced by different applications due to the hardware and software incompatibilities of manufacturing and information processing equipment. But it is this information and operational knowledge which makes up most of the business value of the enterprise and which enables it to compete in the marketplace. Therefore, sufficient and timely information access is a prerequisite for its efficient use in the operation of enterprises. It is the aim of the ESPRIT project AMICE to make this knowledge base available enterprise-wide. During several ESPRIT contracts the project has developed and validated CIMOSA: Open System Architecture for CIM. The CIMOSA concepts provide operation structuring based on cooperating processes. Enterprise operations are represented in terms of functionality and dynamic behaviour (control flow). Information needed and produced, as well as resources and organisational aspects relevant in the course of the operation are modelled in the process model. However, the different aspects may be viewed separately for additional structuring and detailing during the enterprise engineering process.

This work presents a new, abstract and comprehensive view of open distributed systems. The starting point is a small number of core concepts and basic principles, which are informally introduced and precisely defined using mathematical logic. It is shown how the basic concepts of open systems interconnection (OSI), which are currently the most important standardization activities in the context of open distributed systems, can be obtained by specialization and extension of these basic concepts. Application examples include the formal treatment of the interaction point concept and the hierarchical development of communication systems. This book is a contribution to the field of software engineering in general and to the design of open distributed systems in particular. It is oriented towards the design and implementation of real systems, and brings together both formal logical reasoning and current software engineering practice.

These proceedings contain the papers presented at the Advanced Research Working Conference on Correct Hardware Design Methodologies, held in Arles, France, in May 1993, and organized by the ESPRIT Working Group 6018 CHARME-2and the Universit de Provence, Marseille, in cooperation with IFIP Working Group 10.2. Formal verification is emerging as a plausible alternative to exhaustive simulation for establishing correct digital hardware designs. The validation of functional and timing behavior is a major bottleneck in current VLSI design systems, slowing the arrival of products in the marketplace with its associated increase in cost. From being a predominantly academic area of study until a few years ago, formal design and verification techniques are now beginning to migrate into industrial use. As we are now witnessing an increase in activity in this area in both academia and industry, the aim of this working conference was to bring together researchers and users from both communities.

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.

Contents: Optimality and Duality. - Mathematical Programming - Algorithms: -Computational Geometry. - Discrete Optimization. - Linear programming and Complementarity. - Nonlinear Programming. - Optimal Control: - Control Problems. - Distributed Parameter Systems; Stochastic Programming; Applied Modelling and Optimization: Biological and Medical Systems. - Computer-aided Modelling and Design. -Ecology. - Economy and Energy. - Financial Services. - Production and Logistics. - Stochastic Modelling.

Industrial processes such as long-wall coal cutting and me- tal rolling, together with certain areas of 2D signal and image processing, exhibit a repetitive, or multipass struc- ture characterized by a series of sweeps of passes through a known set of dynamics. The output, or pass profile, produced on each pass explicitly contributes to that produced on the text. This interpass interaction can lead to the growth of oscillations, and hence a form of instability, in the se- quence of pass profiles which require control strategies that explicitly incorporate the essential repetitive struc- ture of the process in their decision making. This monograph is unique in developing the new techniques necessary for sy- stematic control systems design in the form of a stability theory and computationally feasible stability tests based on finite simulations and polynomial analysis. Its development requires a basic knowledge of linear frequency domain and state-space theory and a knowledge of basic functional ana- lysis would be beneficial. The text is aimed at researchers in the area of control and systems theory and should also be of interest to those working in the related area of signal and image processing.

The growing demand for information systems of ever-increasing size, scope, and complexity has highlighted the benefits that may be accrued from approaches which recognize the interrelationships between different technological strands in the field of information systems. Typical examples of these areas include: system development methods, CASE, requirements engineering, database design, and re-use. The CAiSE series of conferences provides the forum for the exchange of results and ideas within these different technological spheres from a single perspective, namely that of information systems development and management. The 1992 conference, the fourth in the series, continues this tradition. This volume collects the papers accepted for the conference, with authors from 16 countries covering a wide range of topics including: object-oriented analysis and design methods, the development process and product support, requirements engineering, re-use, design approaches, and deductive approaches.

This book comprehensively introduces data deduplication technologies for storage systems. It first presents the overview of data deduplication including its theoretical basis, basic workflow, application scenarios and its key technologies, and then the book focuses on each key technology of the deduplication to provide an insight into the evolution of the technology over the years including chunking algorithms, indexing schemes, fragmentation reduced schemes, rewriting algorithm and security solution. In particular, the state-of-the-art solutions and the newly proposed solutions are both elaborated. At the end of the book, the author discusses the fundamental trade-offs in each of deduplication design choices and propose an open-source deduplication prototype. The book with its fundamental theories and complete survey can guide the beginners, students and practitioners working on data deduplication in storage system. It also provides a compact reference in the perspective of key data deduplication technologies for those researchers in developing high performance storage solutions.

Increasingly, formal specification is being used by database researchers to describe and understand the systems they are designing and implementing. Similarly, those working on formal specification techniques have recognised that the database field provides a rich context for developing their ideas. However, as experts in one field often have a relatively limited knowledge of the other, there is a growing need for discussion about the relationship between these two fields and how they can be usefully combined. This volume contains the 16 papers which were presented at the International Workshop on Specification on Database Systems, held in Glasgow, 3-5 July 1991. The purpose of the workshop was to bring together these fields and to examine, through a series of invited talks, presentations and working groups, the role that formal specification can play in developing database systems. The papers describe current research into topics such as the formal specification of data models, query languages and transaction handling and the use of formal specification techniques to understand problems which arise in database systems. The working groups, which are summarised at the end of the volume, covered a variety of issues including the role of graphical notations in database specification, the use of specification techniques in enabling "open" or extensible database systems and the education of the database community in specification techniques. This volume will be invaluable to the increasing number of researchers who are using both database systems and formal specification techniques in their work, and who wish to gain a more detailed knowledge of these two fields and the issues which affect them.

This book is an outcome of a 2-days Workshop on Automation Engineering held in Salzhausen (near Hamburg), F.R. Germany. The Workshop is annually organ ized by the Institute of Automation Technology and the Institute of Applied and Physical Chemistry of the University of Bremen. It is regularly joined by 30 to 40 participants representing the teaching and reserarch staff of both Institutes, as weIl as some invited colleagues from other universities and the regional industry. Usually 15/20 selected contributions, grouped in technical sessions (system modelling and identification, control systems design, computer hardware and soft ware, knowledge-based systems, robotics etc.), are presented at the Workshop, whereby the invited guests preferably present survey papers on current problems of modern systems engineering. For this book, 22 papers, contributed to the last two Workshops, are selected and grouped into 6 Chapters. The Chapters reflect the technical sessions listed above and give an average view on current research activities at both Institutes of the University. It is expected that the book will prove as a useful reference to the scientists and practicing engineers in the area of devel opment and application of methods of modern systems engineering in processing industry and the robotics."

The research described in this monograph concerns the formal specification and compositional verification of real-time systems. A real-time programminglanguage is considered in which concurrent processes communicate by synchronous message passing along unidirectional channels. To specifiy functional and timing properties of programs, two formalisms are investigated: one using a real-time version of temporal logic, called Metric Temporal Logic, and another which is basedon extended Hoare triples. Metric Temporal Logic provides a concise notationto express timing properties and to axiomatize the programming language, whereas Hoare-style formulae are especially convenient for the verification of sequential constructs. For both approaches a compositional proof system has been formulated to verify that a program satisfies a specification. To deduce timing properties of programs, first maximal parallelism is assumed, modeling the situation in which each process has itsown processor. Next, this model is generalized to multiprogramming where several processes may share a processor and scheduling is based on priorities. The proof systems are shown to be sound and relatively complete with respect to a denotational semantics of the programming language. The theory is illustrated by an example of a watchdog timer.

In general, distributed systems can be classified into Distributed File Systems (DFS) and Distributed Operating Systems (DOS). The survey which follows distinguishes be tween DFS approaches in Chapters 2-3, and DOS approaches in Chapters 4-5. Within DFS and DOS, I further distinguish "traditional" and object-oriented approaches. A traditional approach is one where processes are the active components in the systems and where the name space is hierarchically organized. In a centralized environment, UNIX would be a good example of a traditional approach. On the other hand, an object-oriented approach deals with objects in which all information is encapsulated. Some systems of importance do not fit into the DFS/DOS classification. I call these systems "closely related" and put them into Chapter 6. Chapter 7 contains a table of comparison. This table gives a lucid overview summarizing the information provided and allowing for quick access. The last chapter is added for the sake of completeness. It contains very brief descriptions of other related systems. These systems are of minor interest or do not provide transparency at all. Sometimes I had to assign a system to this chapter simply for lack of adequate information about it."

documentation is constantly refined as detailed under 1.1 Purpose standing of the requirement increase. The CCT A of the UK government and Siemens For project management purposes the SSADM life Nixdorf (SNI) have undertaken a joint project to com cycle is defined in terms of work packages, modules, pare the CCTA's methodology SSADM and Siemens stages and steps. Each work package is completed when Nixdorf's product GRAPES]). SSADM is an analysis a specified set of documentation is produced and satis and design methodology for computer systems. fies specified quality criteria. All activities undertaken at GRAPES is a graphical language used within the each point are those necessary to produce the required framework provided by the DOMINO@: process tech documentation. nology of Siemens Nixdorf for analysis and design of information systems. (In the 1991 Statement of Direc The analysis is undertaken concentrating on three key tion it was declared the Siemens Nixdorf main line for perspectives: modelling technology.) The study was undertaken in February and March 1991. * functions (users' views of system processing to react to events) The goal of the study was to compare SSADM and * events (real-world business events, e.g. "receipt of DOMINO/GRAPES to discover whether both application"; or system-generated, e.g. end-of-month approaches elicit the same knowledge about a system.

This book presents state-of-the-art research results in the area of formal methods for real-time and fault-tolerant systems. The papers consider problems and solutions in safety-critical system design and examine how wellthe use of formal techniques for design, analysis and verification serves in relating theory to practical realities. The book contains papers on real-time and fault-tolerance issues. Formal logic, process algebra, and action/event models are applied: - to specify and model qualitative and quantitative real-time and fault-tolerant behavior, - to analyze timeliness requirements and consequences of faulthypotheses, - to verify protocols and program code, - to formulate formal frameworks for development of real-time and fault-tolerant systems, - to formulate semantics of languages. The integration and cross-fertilization of real-time and fault-tolerance issues have brought newinsights in recent years, and these are presented in this book.

Verilog HDL is the standard hardware description language for the design of digital systems and VLSI devices. This volume shows designers how to describe pieces of hardware functionally in Verilog using a top-down design approach, which is illustrated with a number of large design examples. The work is organized to present material in a progressive manner, beginning with an introduction to Verilog HDL and ending with a complete example of the modelling and testing of a large subsystem.

With the SPARC (Scalable Processor ARChitecture) architecture and system software as the underlying foundation, Sun Microsys terns is delivering a new model of computing-easy workgroup computing-to enhance the way people work, automating processes across groups, departments, and teams locally and globally. Sun and a large and growing number of companies in the computer industry have embarked on a new approach to meet the needs of computer users and system developers in the 1990s. Originated by Sun, the approach targets users who need a range of compatible computer systems with a variety of application soft ware and want the option to buy those systems from a choice of vendors. The approach also meets the needs of system developers to be part of a broad, growing market of compatible systems and software-developers who need to design products quickly and cost-effecti vel y. The SPARe approach ensures that computer systems can be easy to use for all classes of users and members of the workgroup, end users, system administrators, and software developers. For the end user, the SPARC technologies facilitate system set-up and the daily use of various applications. For the system administrator supporting the computer installation, setting up and monitoring the network are easier. For the software developer, there are ad vanced development tools and support. Furthermore, the features of the SPARC hardware and software technologies ensure that SPARC systems and applications play an important role in the years to come."

In den Proceedings zur 5. Internationalen GI/ITG/GMA-Tagung }ber Fehlerorientierte Rechensysteme in N}rnberg standen Tests, Diagnose und Fehlerbehandlung als Leitthemen im Mittelpunkt. Allerdings wurden auch die Themen Zuverl{ssigkeit, Verf}gbarkeit und Sicherheit in Hard- und Softwaresystemen behandelt. Der Tagungsband gibt mit eingeladenen und eingereichten Beitr{gen, die von einem internationalen Programmausschu~ sorgf{ltig ausgew{hlt wurden, eine ]bersicht }ber den Stand der Forschung, Entwicklung und Anwendungen aller Fehlertoleranz- und Zuverl{ssigkeitsaspekte.

It is many years since Landin, Burge and others showed us how to apply higher order techniques and thus laid some foundations for modern functional programming. The advantage of higher order descriptions - that they can be very succinct and clear - has been percolating through ever since. Current research topics range from the design, implementation and use of higher order proof assistants and theorem provers, through program specification and verification, and programming language design, to its applications in hardware description and verification. The papers in this book represent the presentations made at a workshop held at Banff, Canada, September 10-14 1990 and organised by the Computer Science Department of the University of Calgary. The workshop gathered together researchers interested in applying higher order techniques to a range of problems. The workshop format had a few (but fairly long) presentations per day. This left ample time for healthy discussion and argument, many of which continued on into the small hours. With so much to choose from, the program had to be selective. This year's workshop was divided into five parts: 1. Expressing and reasoning about concurrency: Warren Burton and Ken Jackson, John Hughes, and Faron Moller. 2. Reasoning about synchronous circuits: Geraint Jones and Mary Sheeran (with a bonus on the fast Fourier transform from Geraint). 3. Reasoning about asynchronous circuits: Albert Camilleri, Jo Ebergen, and Martin Rem. 4. Categorical concepts for programming languages: Robin Cockett, Barry Jay, and Andy Pitts.

This volume contains the proceedings ofthe 4th Refinement Workshop which was organised by the British Computer Society specialist group in Formal Aspects of Computing Science and held in Wolfson College, Cambridge, on 9-11 January, 1991. The term refinement embraces the theory and practice of using formal methods for specifying and implementing hardware and software. Most of the achievements to date in the field have been in developing the theoretical framework for mathematical approaches to programming, and on the practical side in formally specifying software, while more recently we have seen the development of practical approaches to deriving programs from their speCifications. The workshop gives a fair picture of the state of the art: it presents new theories for reasoning about software and hardware and case studies in applying known theory to interesting small-and medium-scale problems. We hope the book will be Of interest both to researchers in formal methods, and to software engineers in industry who want to keep abreast of possible applications of formal methods in industry. The programme consisted both of invited talks and refereed papers. The invited speakers were Ib S0rensen, Jean-Raymond Abrial, Donald MacKenzie, Ralph Back, Robert Milne, Mike Read, Mike Gordon, and Robert Worden who gave the introductory talk. This is the first refinement workshop that solicited papers for refereeing, and despite a rather late call for papers the response was excellent.

Reiner Anderl The Advanced Modelling part of the CAD*I project aimed at the development of a new generation of modelling techniques as a basic functionality of future CAD/CAM systems. The methodology and concepts for advanced modelling techniques, their availability in the communication interface of a CAD/CAM system and their influence on internal interfaces in the software architecture of a CAD/CAM system are fundamental results of advanced modelling work. These results form the basis for the development of a new generation of CAD/CAM systems which are called product modelling systems. CAD/CAM systems today mainly support the geometric description of a technical part or its description as a technical drawing. Advanced geometric modelling capabilities deal with parametric design functions embedded into CAD/CAM systems. However, development strategies for future CAD/CAM systems are directed toward the following: 1. The development of product modelling systems and 2. the development of integrated systems based on CAD, CAP (Computer Aided Planning), CAM and other CIM (Computer Integrated Manu facturing) functionalities."