*定義 [#ub8fccc5] -An open set A is co-open , if closure of A is open. *出典 [#cb6453a2] -Abd El-Monsef, M. E.(ET-TANT) and Kozae, A. M.(ET-TANT),''Remarks on $s$-closed spaces (Arabic summary)'', Qatar Univ. Sci. Bull. 6 (1986), 11--21.
*定義 [#ub8fccc5] -An open set A is co-open , if closure of A is open. *出典 [#cb6453a2] -Abd El-Monsef, M. E.(ET-TANT) and Kozae, A. M.(ET-TANT),''Remarks on $s$-closed spaces (Arabic summary)'', Qatar Univ. Sci. Bull. 6 (1986), 11--21.