Snapshot verification

Abstract

The classical model for concurrent systems is based on observing execution sequences of global states, separated from each other by atomic transitions. This model is intuitively simple and enjoys a variety of mathematical tools, e.g., finite automata and linear temporal logic, and algorithms that can be applied in order to test and verify concurrent systems. Although this model is sufficient for most frequently used validation tasks, some phenomena of concurrent systems are difficult to express using its related formalisms. In particular, not all the global states (snapshots) related to an execution appear on a particular execution sequence; some appear on equivalent sequences. Previous attempts to move into formalisms that are based on a more detailed model of execution, e.g,. the causality based model, resulted in specification formalisms with inherently high complexity verification algorithms. We study here verification problems that involve allowing the execution sequences model to observe past global states from equivalent executions. We show various algorithms and complexity results related to our extension of the interleaving model. © Springer-Verlag Berlin Heidelberg 2005.