Edge density

Edge density --- рёберная плотность.

Given an undirected graph [math]\displaystyle{ G = (V,E) }[/math] and a nonempty subset [math]\displaystyle{ X \subseteq V }[/math], the edge density of [math]\displaystyle{ X }[/math] is given by

[math]\displaystyle{ \rho(X) = |V||E_{X}|/|X||V \setminus X|, }[/math]

where [math]\displaystyle{ E_{X} }[/math] is the set of all edges with one end in [math]\displaystyle{ X }[/math] and the other end in [math]\displaystyle{ V \setminus X }[/math].