Mei He and Ying Ge and Jingyu Qian
On an Open Problem for Definable Subsets of Covering Approximation Spaces
511 - 513
2011
5
3
International Journal of Mathematical and Computational Sciences
https://publications.waset.org/pdf/7038
https://publications.waset.org/vol/51
World Academy of Science, Engineering and Technology
Let (U;D) be a Grcovering approximation space
(U; C) with covering lower approximation operator D and covering
upper approximation operator D. For a subset X of U, this paper
investigates the following three conditions (1) X is a definable subset
of (U;D); (2) X is an inner definable subset of (U;D); (3) X is an
outer definable subset of (U;D). It is proved that if one of the above
three conditions holds, then the others hold. These results give a
positive answer of an open problem for definable subsets of covering
approximation spaces.
Open Science Index 51, 2011