OCR D2 — Question 3

Exam BoardOCR
ModuleD2 (Decision Mathematics 2)
TopicNetwork Flows

  1. A sheet is provided for use in answering this question.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{df7b056f-1446-43f1-a2fd-c0d56533550e-3_588_1285_287_296} \captionsetup{labelformat=empty} \caption{Fig. 1}
\end{figure} Figure 1 shows a capacitated, directed network. The numbers on each arc indicate the minimum and maximum capacity of that arc. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{df7b056f-1446-43f1-a2fd-c0d56533550e-3_648_1288_1155_296} \captionsetup{labelformat=empty} \caption{Fig. 2}
\end{figure} Figure 2 shows a feasible flow through the same network.
  1. Using this as your initial flow pattern, use the labelling procedure to find a maximal flow. You should list each flow-augmenting route you use together with its flow and draw the maximal flow pattern.
    (6 marks)
  2. Find a cut of the same value as your maximum flow and explain why this proves it gives the maximim possible flow.