Algebraic structures and lattice structures of rough sets are basic and important topics in
rough sets theory. In this paper we pointed out that a basic problem had been overlooked …

The generalizations of rough sets considered with respect to similarity relation, covers and
fuzzy relations, are main research topics of rough set theory. However, these generalizations …

This paper specifically studies the classes of rough sets and fuzzy rough sets. We discuss
the invertible lower and upper approximations and present the necessary and sufficient …

Covering rough sets are natural extensions of the classical rough sets by relaxing the
partitions to coverings. Recently, the concept of neighborhood has been applied to define …

In this paper, two L-rough approximation operators are defined by an arbitrary mapping from
the set of all singletons to the set of all L-sets, which is a graded extension of Järvinen's …

In rough set theory, the lower and upper approximation operators defined by a fixed binary
relation satisfy many interesting properties. Several authors have proposed various fuzzy …

Four kinds of constructive methods of rough approximation operators from existing rough
sets are established, and the important conclusion is obtained: some rough sets are …

Rough set theory was developed by Pawlak as a formal tool for approximate reasoning
about data. Various fuzzy generalizations of rough approximations have been proposed in …

In rough set theory, upper and lower approximation operators are two crucial concepts. The
study of these two approximation operators in the framework of lattice theory is an important …

Rough sets and fuzzy sets have been proved to be powerful mathematical tools to deal with
uncertainty, it soon raises a natural question of whether it is possible to connect rough sets …