TY - JFULL
AU - Mei He and Ying Ge and Jingyu Qian
PY - 2011/4/
TI - On an Open Problem for Definable Subsets of Covering Approximation Spaces
T2 - International Journal of Mathematical and Computational Sciences
SP - 510
EP - 513
VL - 5
SN - 1307-6892
UR - https://publications.waset.org/pdf/7038
PU - World Academy of Science, Engineering and Technology
NX - Open Science Index 51, 2011
N2 - 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.
ER -