Incremental approaches to computing approximations of sets in dynamic covering approximation spaces

Abstract

In practical situations, it is of interest to investigate computing approximations of sets as an important step of attribute reduction in dynamic covering information systems. In this paper, we present incremental approaches to computing the type-1 and type-2 characteristic matrices of coverings with the variation of elements. Then we construct the second and sixth lower and upper approximations of sets by using incremental approaches from the view of matrices. We also employ examples to show how to compute approximations of sets by using the incremental and non-incremental approaches in dynamic covering approximation spaces.