*Definition [#refd751f]
-A topological space (X,τ) is called semi-D_2 if for any distinct pair of points x and y of X , there exist disjoint [[sD-sets>semi-Difference set]] &ref(http://www.eaflux.com/imgtex/imgtex.fcgi?%5bres=100%5d%7b%5c%5b%20U%5cmbox%7b%20and%20%7dV%5cmbox%7b%20such%20that%20%7d%20x%5cin%20U%5cmbox%7b%20and%20%7d%20y%5cin%20V%20%5c%5d%7d%25.png);.

*Property [#yc746800]
-If (X,τ) is semi-D_2, then it is [[semi-D_1]].

*Reference [#o6bad28f]
-Athisaya Ponmani, S.; Lellis Thivagar, M., ''Another form of separation axioms.'' ,  (English) [J] Methods Funct. Anal. Topol. 13, No. 4, 380-385 (2007).