A set-valued information system (SVIS) is the generalization of a single-valued information
system. A SVIS with missing information values is called an incomplete set-valued …

For set-valued information systems, there are many original dot-based approximation
models based on tolerance relations and other developed tolerance relations. Because of …

A hybrid information system is an information system where there exist varieties of data, and
its information structures reflect the internal features of this kind of information system. This …