Fred B. Schneider
Ph.D. State University of New York at Stony Brook, 1978

My research focuses on techniques to support construction of concurrent and distributed systems for high-integrity, mission-critical settings.

The TACOMA project-a collaboration involving Cornell and the University of Tromsų (Norway)-is studying the use of mobile processes, or agents, for structuring distributed systems. Agents are a promising new paradigm for implementing services in large, open, distributed systems, like the Internet. Work at Cornell on TACOMA has emphasized fault-tolerance. Joint with Y. Minsky, S. Stoller, and R. van Renesse, a number of solutions to the "agent-integrity problem" have been developed over the past year. Agents comprising an application must not only survive (possibly malicious) failures of the hosts they visit, but they must also be resilient to potentially hostile actions by other hosts. Replication and voting enable an application to survive some failures of the hosts it visits. However, even hosts that are not visited by agents can masquerade and confound a replica-management scheme. We want correctness of a computation to be independent of hosts that would not be visited in a failure-free run, and we have developed protocols that use cryptographic techniques in novel ways for this purpose.

I have also been heavily involved in developing approaches for assertional reasoning about systems, since this is one way to gain confidence that a component satisfies its specification. I succeeded in identifying ways that assertional reasoning can drive the design of a distributed program. David Gries and I continue investigating first-order equational logics and the calculational-style of proof. This year, we studied the handling of undefined terms (i.e. partial functions) and developed an axiomatization for Dijkstra's "everywhere" operator.


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