关键词: 粗糙集, 覆盖, 依赖, 上近似

Abstract: Covering rough sets theory is an extension to classical rough sets. There are many ways to define covering rough upper approximation. Different points of view lead to different definitions in studying covering upper approximation. This paper proposes a concept called elements relationship, and by using the concept it defines covering rough sets upper approximation named element-dependent upper approximation. Different from other upper approximation, a dependency upper approximation is a definable set, and from the view of covering, it has the property of less covering-element numbers compared with other covering upper approximation.

Key words: rough set, covering, dependency, upper approximation