Friedrich W. von Henke

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Clock synchronization algorithms play a crucial role in a variety of fault-tolerant distributed architectures. Although those algorithms are similar in their basic structure, the particular designs diier considerably , for instance in the way clock adjustments are computed. This paper develops a formal generic theory of clock synchronization algorithms(More)
| PVS is the most recent in a series of verii-cation systems developed at SRI. Its design was strongly innuenced, and later reened, by our experiences in developing formal speciications and mechanically checked verii-cations for the fault-tolerant architecture, algorithms, and implementations of a model \reliable computing platform" (RCP) for life-critical(More)
We describe our experience with formal, machine-checked verification of algorithms for critical ap-, placations, concentrating on a Byzantine fault-tolerant algorithm for synchronizing the clocks in the replicated computers of a digit al flight control system. First, we explain the problems encountered in unsynchronized systems and the necessity, and(More)
This paper describes our experience using coordinated atomic (CA) actions as a system structuring tool to design and validate a sophisticated control system for a complex industrial application that has high reliability and safety requirements. Our study is based on the "Fault-Tolerant Production Cell", which represents a manufacturing process involving(More)
We describe a formal speciication and mechanically checked veriica-tion of the Interactive Convergence Clock Synchronization Algorithm of Lamport and Melliar-Smith 16]. In the course of this work, we discovered several technical aws in the analysis given by Lamport and Melliar-Smith, even though their presentation is unusually precise and detailed. As far(More)
Schneider Sch87] generalizes a number of protocols for Byzantine fault-tolerant clock synchronization and presents a uniform proof for their correct-ness. We present a mechanical veriication of Schneider's protocol leading to several signiicant clariications and revisions. The veriication was carried out with the Ehdm system RvHO91] developed at the SRI(More)