Edexcel D2 — Question 5

Exam BoardEdexcel
ModuleD2 (Decision Mathematics 2)
TopicNetwork Flows

5. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{e80fcab6-7c7d-4a0c-84e0-c23f5a969a75-4_924_1646_221_207} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} Figure 1 shows a capacitated, directed, network. The capacity of each arc is shown on that arc and the numbers in circles represent an initial flow from S to T . Two cuts, \(\mathrm { C } _ { 1 }\) and \(\mathrm { C } _ { 2 }\) are shown on Figure 1.
  1. Find the capacity of each of the two cuts and the value of the initial flow.
    (3)
  2. Complete the initialisation of the labelling procedure on Figure 1 in the answer book, by entering values along \(\mathrm { SB } , \mathrm { AB } , \mathrm { BE }\) and BG .
    (2)
  3. Hence use the labelling procedure to find a maximum flow of 85 through the network. You must list each flow-augmenting path you use, together with its flow.
    (5)
  4. Show your flow pattern on Figure 2.
    (2)
  5. Prove that your flow is maximal.
    (2)