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A formal specification and mechanically assisted verification of the interactive convergence clock synchronization algorithm of Lamport and Melliar-Smith is described. Several technical flaws in the analysis given by Lamport and Melliar-Smith were discovered, even though their presentation is unusally precise and detailed. It seems that these flaws were not detected by informal peer scrutiny. The flaws are discussed and a revised presentation of the analysis is given that not only corrects the flaws but is also more precise and easier to follow. Some of the corrections to the flaws require slight modifications to the original assumptions underlying the algorithm and to the constraints on its parameters, and thus change the external specifications of the algorithm. The formal analysis of the interactive convergence clock synchronization algorithm was performed using the Enhanced Hierarchical Development Methodology (EHDM) formal specification and verification environment. This application of EHDM provides a demonstration of some of the capabilities of the system. Rushby, John and Vonhenke, Frieder Unspecified Center NASA-CR-4239, NAS 1.26:4239 NAS1-17067; RTOP 505-66-21-01...
This volume contains the proceedings of FTRTFT 2002, the International S- posium on Formal Techniques in Real-Time and Fault-Tolerant Systems, held at the University of Oldenburg, Germany, 9–12 September 2002. This sym- sium was the seventh in a series of FTRTFT symposia devoted to problems and solutions in safe system design. The previous symposia took place in Warwick 1990, Nijmegen 1992, Lub ̈ eck 1994, Uppsala 1996, Lyngby 1998, and Pune 2000. Proceedings of these symposia were published as volumes 331, 571, 863, 1135, 1486, and 1926 in the LNCS series by Springer-Verlag. This year the sym- sium was co-sponsored by IFIP Working Group 2.2 on Formal Description of Programming Concepts. The symposium presented advances in the development and use of formal techniques in the design of real-time, hybrid, fault-tolerant embedded systems, covering all stages from requirements analysis to hardware and/or software - plementation. Particular emphasis was placed on UML-based development of real-time systems. Through invited presentations, links between the dependable systems and formal methods research communities were strengthened. With the increasing use of such formal techniques in industrial settings, the conference aimed at stimulating cross-fertilization between challenges in industrial usages of formal methods and advanced research. Inresponsetothecallforpapers,39submissionswerereceived.Eachsubm- sion was reviewed by four program committee members assisted by additional referees. At the end of the reviewing process, the program committee accepted 17 papers for presentation at the symposium.
This book presents the proceedings of the 9th International Conference of Z Users, ZUM '95, held in Limerick, Ireland in September 1995. The book contains 34 carefully selected papers on Z, using Z, applications of Z, proof, testing, industrial usage, object orientation, animation of specification, method integration, and teaching formal methods. Of particular interest is the inclusion of an annotated Z bibliography listing 544 entries. While focussing on Z, by far the most commonly used "formal method" both in industry and application, the volume is of high relevance for the whole formal methods community.
This state-of-the-art monograph presents a coherent survey of a variety of methods and systems for formal hardware verification. It emphasizes the presentation of approaches that have matured into tools and systems usable for the actual verification of nontrivial circuits. All in all, the book is a representative and well-structured survey on the success and future potential of formal methods in proving the correctness of circuits. The various chapters describe the respective approaches supplying theoretical foundations as well as taking into account the application viewpoint. By applying all methods and systems presented to the same set of IFIP WG10.5 hardware verification examples, a valuable and fair analysis of the strenghts and weaknesses of the various approaches is given.
What started with the sundial has, thus far, been refined to a level of precision based on atomic resonance: Time. Our obsession with time is evident in this continued scaling down to nanosecond resolution and beyond. But this obsession is not without warrant. Precision and time synchronization are critical in many applications, such as air traffic
With the omnipresence of micro devices in our daily lifes embedded software has gained tremendous importance in both science and industry. This volume contains 34 invited papers from the First International Workshop on Embedded Systems. They present latest research results from different areas of computer science that are traditionally distinct but relevant to embedded software development (such as, for example, component based design, functional programming, real-time Java, resource and storage allocation, verification). Each paper focuses on one topic, showing the inter-relationship and application to the design and implementation of embedded software systems.
Timo Warns has developed tractable fault models that, while being non-probabilistic, are accurate for dependent and propagating faults. Using seminal problems such as consensus and constructing coteries, he demonstrates how the new models can be used to design and evaluate effective and efficient means of fault tolerance.