We define -closure operator as a new topological operator which lies between the -closure and the -closure. Some relationships between this new operator and each of -closure, -closure, and usual closure are obtained. Via -closure operator, we introduce -open sets as a new topology. Some mapping theorems related to the new topology are given. 2 topological spaces are characterized in terms of -closure operator. Also, we use -open sets to define -regularity as a new separation axiom which lies strictly between -regularity and regularity. For a given topological space ( , ), we show that -regularity is equivalent to the condition = . Finally, -continuity, --continuity, weak -continuity, and faint -continuity are introduced and studied.
Definition 2.1.[1] Let be a subset of a ts ( , ).a. The -closure of is denoted by ( ) and defined by