A framework for temporal functional dependencies with multiple granularities

Temporal functional dependencies (TFDs) add a temporal component to classical functional dependencies to deal with temporal data. As an example, while functional dependencies model constraints like "employees with the same role get the same salary", TFDs can represent constraints like "for any given month, employees with the same role get the same salary (but their salary may change from one month to the next one)" or "current salaries of employees uniquely depend on their current and previous roles". In this paper, we propose a general framework for specifying TFDs, possibly involving different time granularities, and for checking whether or not a given database instance satisfies them. The proposed framework subsumes existing formalisms for TFDs and it allows one to encode TFDs which are not captured by them.