document: Neighborhood operator systems and approximations This paper presents a framework for the study of generalizing the standard notion of equivalence relation in rough set approximation space with various categories of k-step neighborhood systems . Based on a binary relation on a finite universe , six families of binary relations are obtained , and the corresponding six classes of k-step neighborhood systems are derived . Extensions of Pawlak 's -LRB- 1982 -RRB- rough set approximation operators based on such neighborhood systems are proposed . Properties of neighborhood operator systems and rough set approximation operators are investigated , and their connections are examined
doc_bio_tags: B I I O O O O O O O O O O O O O O O O B I O B I I I O O O O O O O O O O O B I O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O