@article{(Open Science Index):https://publications.waset.org/pdf/7038, title = {On an Open Problem for Definable Subsets of Covering Approximation Spaces}, author = {Mei He and Ying Ge and Jingyu Qian}, country = {}, institution = {}, abstract = {Let (U;D) be a Gr-covering 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.}, journal = {International Journal of Mathematical and Computational Sciences}, volume = {5}, number = {3}, year = {2011}, pages = {511 - 513}, ee = {https://publications.waset.org/pdf/7038}, url = {https://publications.waset.org/vol/51}, bibsource = {https://publications.waset.org/}, issn = {eISSN: 1307-6892}, publisher = {World Academy of Science, Engineering and Technology}, index = {Open Science Index 51, 2011}, }