Relations arising from coverings and their topological structures

Covering rough sets are an important extension of Pawlak rough sets. This paper studies the relations arising from coverings and their topological structures. Every covering induces a reflexive and transitive relation. We represent the approximate pairs proposed by Ma (2015) [20] with different combinations of a relation and its inverse. Based on this representation, we give the relationship among approximate pairs. We also consider the topological structures induced by these lower approximations and establish the relationship among these topologies. The results show that the approximate pairs can be precisely characterized by a relation and its inverse.