A directed graph (DG) g is a graph g = G,V, but here the edges E are given as a set of ordered pairs like E = {(v,v') (v, v') V V}. This kind of edges is called arcs. An arc is written as v v'. In an arc v v' is v called the predecessor of v' and v' is called the successor of v.

Gerd Doeben-Henisch 2010-03-03