A rough set approach for approximating differential dependencies.

•A differential-relation-based rough set model on relational databases is proposed.•Using this model, the measures for differential dependencies (DDs) are expressed.•An efficient method to compute the approximate error measure of g3 for DDs is developed.•The rough sets on the differential decision systems (DDSs) are introduced.•A bridge between DDs in databases and attribute dependencies in DDSs is formed.