Zone-interval reprezentation

Zone-interval reprezentation --- зонно-интервальное представление.

A sequence of different cf-graphs [math]\displaystyle{ G_0, G_1, \ldots, G_r }[/math] is called a zone-interval representation of the cf-graph [math]\displaystyle{ G }[/math], if [math]\displaystyle{ G_0=G }[/math], [math]\displaystyle{ G_r }[/math] contains no zones and for all [math]\displaystyle{ i }[/math], [math]\displaystyle{ 0\lt i\leq r }[/math], the graph [math]\displaystyle{ G_i }[/math] is obtained from [math]\displaystyle{ G_{i-1} }[/math] by reduction of mutually disjoint intervals, being zones, into nodes.