Critical Path (sub-graph)
Compute the longest path in a graph G = <V,E,delay,Origin> (delay is set of labels, Origin is the super-source of the DAG)
for each edge <v,w> from v
Final-delay(w) = max(Final-delay(w), delay(v) + delay(w) + delay(<v,w>))
if all incoming edges of W have been traversed