Density --- плотность.
Let be a graph with a vertex set and an edge set . The density of is defined by
is said to be balanced if for each subgraph of we have , where V(H) is assumed to be nonempty. If is not balanced, then it contains a subgraph with greater density than that of . In particular, we use to denote the maximum density of a subgraph of , i.e.
is called the global density of .