Relational characterizations of system fault tolerance

Fault tolerance is the ability of a system to continue delivering its services after faults have caused errors. We have argued, in the past, that complex and/or critical systems are best validated by a wide range of methods, including proving, testing, and fault tolerance; we have also argued that in order to use these methods in concert, we need to cast them in a common framework. In this paper, we present mathematical characterizations of fault tolerance properties, using a relational calculus.