DFS edge classification
= DFS edge classification
{c}
Classify <directed edges> relative to a <depth-first search> forest. Tree <edges> discover a new <vertex>; forward <edges> reach a proper descendant without being its discovery <edge>; back <edges> reach an active ancestor; cross <edges> connect completed branches or trees. Discovery and finish intervals are nested for ancestry. The classification depends on the chosen search order, not only on the <graph>.