T_{EF}

Definition

• A topological space (X,τ) said to be a T_{EF} if every finite subset of X is either open or closed.

Property

• T_{EF} ⇒ T_{FF}.
• T_{EF} ⇒ T_{ES}.

Reference

• McSherry, D. M. G. , On separation axioms weaker than T_1. , Proc. Roy. Irish Acad. Sect. A 74 (1974), 115–118.