Hausdorff axiom

One of the separation axioms (cf. Separation axiom). It was introduced by F. Hausdorff in 1914 (see [1]) in his definition of the concept of a topological space. The Hausdorff axiom holds in a topological space if any two (distinct) points of it have disjoint neighbourhoods. A space satisfying the Hausdorff axiom is called a Hausdorff space or a $T_2$-space.

References

[1]	F. Hausdorff, "Set theory" , Chelsea, reprint (1978) (Translated from German)

References

[a1]	A.V. Arkhangel'skii, V.I. Ponomarev, "Fundamentals of general topology: problems and exercises" , Reidel (1984) (Translated from Russian)