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Although building systems from components has attractions, this approach also has problems. Can we be sure that a certain configuration of components is correct? Can it perform as well as a monolithic system? Our paper answers these questions for the Ensemble communication architecture by showing how, with help of the Nuprl formal system, configurations may(More)
– The Horus and Ensemble efforts culminated a multi-year Cornell research program in process group communication used for fault-tolerance, security and adaptation. Our intent was to understand the degree to which a single system could offer flexibility and yet maintain high performance, to explore the integration of fault-tolerance with security and(More)
Ensemble is a widely used group communication system that supports distributed programming by providing precise guarantees for synchronization, message ordering, and message delivery. Ensemble eases the task of distributed-application programming, but as a result, ensuring the correctness of Ensemble itself is a diicult problem. In this paper we use I/O(More)
This article uses the Internet as a starting point to illustrate universal aspects of complex systems throughout technology and biology. Complexity in most systems is driven by the need for robustness to uncertainty in their environments and component parts far more than by basic functionality. Protocols organize highly structured and complex modular(More)
In this paper we introduce the Caltech Multi-Vehicle Wireless Testbed (MVWT), a platform for testing decentralized control methodologies for multiple vehicle coordination and formation stabilization. The testbed consists of eight mobile vehicles, an overhead vision system that provides GPS-like state information and wireless Ethernet for communications.(More)
MetaPRL is the latest system to come out of over twenty five years of research by the Cornell PRL group. While initially created at Cornell, MetaPRL is currently a collaborative project involving several universities in several countries. The MetaPRL system combines the properties of an interactive LCF-style tactic-based proof assistant, a logical(More)
Theorem proving techniques are particularly well suited for reasoning about arithmetic above the bit level and for relating diierent levels of abstraction. In this paper we show h o w a non-restoring integer square root algorithm can be transformed to a very eecient hardware implementation. The top level is a Standard ML function that operates on unbounded(More)
Higher-order logics are expressive tools for tasks ranging from formalizing the foundations of mathematics to large-scale software veriication and synthesis. Because of their complexity, proofs in higher-order logics often use a combination of interactive proving together with computationally-intensive tactic applications that perform proof automation. As(More)