Normally symmetric graph

Normally symmetric graph --- нормально симметричный граф.

A graph [math]\displaystyle{ G = (V,A) }[/math] is called normally symmetric graph if the number of all common servers [math]\displaystyle{ d^{+}(u,v) }[/math] is equal to the number of all common receivers [math]\displaystyle{ d^{-}(u,v) }[/math] for any [math]\displaystyle{ u,v \in V }[/math].