Almost discrete space

Definition
A topological space is termed almost discrete if it satisfies the following equivalent conditions:


 * 1) Every open subset is a closed subset
 * 2) Every closed subset is an open subset
 * 3) It is both an defining ingredient::Alexandrov space (i.e., it is finitely generated) and a defining ingredient::zero-dimensional space (i.e., it has a basis of clopen subsets).