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L. Gréaux, R. Kuznets, L. Prosperi, U. Schmid:
"What do Byzantine agents know?";
Talk: First joint workshop by the Mathematics and the Philosophy Research Institutes of UNAM, Mexiko-Stadt, Mexiko (invited); 2018-08-06 - 2018-08-09.

The idea to analyze communication in distributed systems using epistemic logic, the logic of knowledge, has been around for more than 25 years and yielded such seminal results as the necessity of common knowledge as a precondition for simultaneous coordinated action. The goal of this ongoing project is to incorporate Byzantine agents, i.e., agents prone to failure, into the epistemic framework. Some limited types of Byzantine behaviours have already been studied in this respect, e.g., crash failures by Dwork and Moses. But handling knowledge in such limited circumstances is more straightforward.
We consider fully Byzantine agents whose behavior is maximally unrestricted but whose knowledge remains local. Failures of such agents to follow their protocol may happen due to malicious intent or to malfunction. Epistemically, the latter case presents more interest. In particular, a natural goal is for a protocol to take into account and try to remedy possible failures, which would require the agent to know a failure has occurred.
Our contribution is a comprehensive and modular distributed framework for message passing, incorporating the possibility of arbitrary failures by agents. We demonstrate the potential of this framework by providing a modular way of incorporating into it various popular communication contexts, including synchronous agents, synchronous communication, broadcast (both hardware and software), coordinated action, etc. Joint work with Lucas Gréaux, Laurent Prosperi, and Ulrich Schmid, in alphabetical order.

distributed systems, Byzantine agents