α-open

Definition

A set is said to be α-open if it is the difference of an open and a nowhere dense set.

Remark

• Every α-open set is preopen but not vice versa.

Reference

J. Dontchev, M. Ganster and T. Noiri, On p-closed spaces, Internat. J. Math. & Math. Sci. Vol.24, No.3 (2000) pp.203-212.