A flow network G = (V, E) is a directed graph where each edge (u,v) E has capacity c(u,v) 0.
If (u,v) E, then c(u,v) = 0.
Distinguish source (s V) and sink (t V) as the vertices between
which the flow is to be maximized.
For every v V, v is on a path from s to t.
, therefore the graph is connected.