λ-open

Definition

• A subset S of a topological space (X,τ) is called λ-open if the complement of S is λ-closed.

Reference

• Caldas Miguel, Jafari Saeid, Navalagi Govindappa, More on λ-closed sets in topological spaces.,Rev. Colombiana Mat. 41 (2007), no. 2, 355-369.