Certainty-Based Rough Sets

The departing point of this study is a data table with certainty values associated to attribute values. These values are deeply rooted in possibility theory, they can be obtained with standard procedures and they are efficiently manageable in databases. Our aim is to study rough set approximations and reducts in this framework. We define three categories of approximations that make use of the certainty value and generalize different aspects of the approximations: their equation, the binary relation used and the granulation. Further, new kinds of reducts aimed to make use or reduce the information provided by the certainty values are given.