ν-open

Definition

A subset U of a topological space X is called ν-open if there is a regular open subset V of X such that V⊂U⊂cl(V).

Reference

S. Balasubramanian, C.Sandhya and P.Aruna Swathi Vyjayanthi, Note on Regularity and ν-compactness, Int. J. Contemp. Math. Sciences, Vol. 5, (2010) no. 16, 777-784