Approximation Operator Based on Neighborhood Systems.

In this paper, we propose a new covering-based set in which the lower and the upper approximation operations are defined by neighborhood systems. We systematically discuss this new type of covering-based set in two steps. First, we study the basic properties of this covering-based set, such as normality, contraction, and monotone properties. Second, we discuss the relationship between the new type of covering-based set and the other ten proposed sets. [ABSTRACT FROM AUTHOR]