Edexcel D1 2004 June — Question 5

Exam BoardEdexcel
ModuleD1 (Decision Mathematics 1)
Year2004
SessionJune
TopicSorting Algorithms

5. Figure 3
\includegraphics[max width=\textwidth, alt={}, center]{f4258313-53d5-4a88-abf9-c0c7926770e4-6_584_992_287_589} Figure 3 shows a capacitated directed network. The number on each arc is its capacity. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 4} \includegraphics[alt={},max width=\textwidth]{f4258313-53d5-4a88-abf9-c0c7926770e4-6_585_979_1101_561}
\end{figure} Figure 4 shows a feasible initial flow through the same network.
  1. Write down the values of the flow \(x\) and the flow \(y\).
  2. Obtain the value of the initial flow through the network, and explain how you know it is not maximal.
  3. Use this initial flow and the labelling procedure on Diagram 1 in this answer book to find a maximum flow through the network. You must list each flow-augmenting route you use, together with its flow.
  4. Show your maximal flow pattern on Diagram 2.
  5. Prove that your flow is maximal.