Mixed graph

Mixed graph --- смешанный граф.

A mixed graph [math]\displaystyle{ D }[/math] consists of a vertex set [math]\displaystyle{ V(D) }[/math] and a set of edges and arcs [math]\displaystyle{ E(D) }[/math]. A mixed graph without edges is a digraph. A mixed graph [math]\displaystyle{ D }[/math] is connected, if the underlying graph of [math]\displaystyle{ D }[/math] is connected.