Expressing and detecting control flow properties of distributed computations

Properties of distributed computations can be either on their global states or on their control flows. This paper addresses control flow properties. It first presents a simple yet powerful logic for expressing general properties on control flows, seen as sequences of local states. Among other properties, we can express invariance, sequential properties (20 satisfy such a property a control flow must match a pattern described as a word on some alphabet) and non-sequential properties (these properties are on several control flows at the same time). A decentralized detection algorithm for properties described by this logic is then presented. This algorithm, surprisingly simple despite the power of the logic, observes the underlying distributed computation, does not alter its control flows and uses message tags to carry detection-related information.