Ontological Modeling of Time and Time-Based Reasoning for Systems of Systems

This paper explores the critical issue of temporal modeling and reasoning for successful systems of systems (SoS) architecting and operations. The increasing complexity of missions results into needs to leverage capabilities of constituent systems (CSs) in multiple domains, distributed geographically and temporally (different time zones) too. This introduces issues capable of hindering mission success including clock drifts and synchronization as well as communication delays. To assure correctness of SoS functionality in the face of these challenges, we develop and introduce a new ontological framework for modeling and time-based reasoning in SoS. Knowledge representation of time and temporal semantics in SoS modeling are discussed with a focus on the central role description logics (DL) and interval-based time semantics play in the development of the new framework. The latter consists of a DL-backed theoretical foundation providing formalisms to ontological models encapsulating temporal knowledge on top of which time-based modeling and reasoning applications for SoS can be built. A prototype implementation with a military-directed SoS has been illustrated and is currently under development.