Definition
- A subset S ⊂ X is called a λ-Difference set (in short λ-D-set), if there
are two λ-open sets U , V in X such that .
Reference
- Caldas Miguel, Jafari Saeid, Navalagi Govindappa, More on λ-closed sets in topological spaces.,Rev. Colombiana Mat. 41 (2007), no. 2, 355-369.