DFS tree

Given the run a DFS algorithm on a directed graph , the DFS tree is a sub-forest where are the edges used by to first explore a vertex.

Edges in can be described in relation to the edges in .

Edges

An edge can be described as one of the following in relation to :

  • Tree edges: edges
  • Back edges: edges that connect two nodes in the same branch where the origin node is further away from the root node than the terminus.
  • Forward edges: edges that connect two nodes in the same branch where the origin node is closer to the root node than the terminus.
  • Cross edges: edges that connect two branches.