Auxiliary digraph for computing flow based edge connectivity
If the input graph is undirected, we replace each edge (
u,`v`) with two reciprocal arcs (
v) and (
u) and then we set the attribute ‘capacity’ for each arc to 1. If the input graph is directed we simply add the ‘capacity’ attribute. Part of algorithm 1 in  .
Abdol-Hossein Esfahanian. Connectivity Algorithms. (this is a chapter, look for the reference of the book). http://www.cse.msu.edu/~cse835/Papers/Graph_connectivity_revised.pdf