title: On twelve types of covering-based rough sets.
abstract: Covering approximation spaces are a generalization of equivalence-based rough set theories. In this paper, we will consider twelve types of covering based approximation operators by combining four types of covering lower approximation operators and three types of covering upper approximation operators. Then, we will study the properties of these new pairs and show they have most of the common properties among existing covering approximation pairs. Finally, the relation between these new pairs is studied.
authors.affiliation: Department of Computer Science, Yazd University, Yazd, Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Safari
authors.affiliation: Department of Computer Science, Yazd University, Yazd, Iran ; The Laboratory of Quantum Information Processing, Yazd University, Yazd, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Hooshmandasl
keywords: Approximation operators; Approximation spaces; Covering spaces; Rough sets