Edexcel D2 2013 June — Question 6

Exam BoardEdexcel
ModuleD2 (Decision Mathematics 2)
Year2013
SessionJune
TopicNetwork Flows

6. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{0af7fd3e-68af-41fc-883b-3bc2589035bb-7_816_1138_178_459} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} Figure 1 shows a capacitated directed network. The number on each arc represents the capacity of that arc. The numbers in circles represent an initial flow.
  1. State the value of the initial flow.
  2. On Diagram 1 and Diagram 2 in the answer book, add a supersource S and a supersink T . On Diagram 1, show the minimum capacities of the arcs you have added.
  3. Complete the initialisation of the labelling procedure on Diagram 2 in the answer book by entering values on the arcs to S and T and on \(\operatorname { arcs } \mathrm { CD }\), DE , DG , FG, FI and GI.
  4. Find the maximum flow through the network. You must list each flow-augmenting route you use, together with its flow.
  5. Show your maximum flow on Diagram 3 in the answer book.
  6. Prove that your flow is maximal.