Edexcel D2 2007 June — Question 5

Exam BoardEdexcel
ModuleD2 (Decision Mathematics 2)
Year2007
SessionJune
TopicNetwork Flows

5. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 1} \includegraphics[alt={},max width=\textwidth]{0e86cb18-2c6e-49f1-b235-aa15eb83e260-3_1026_1609_772_169}
\end{figure} In solving a network flow problem using the labelling procedure, the diagram in Figure 1 was created.
The arrow on each arc indicates the direction of the flow along that arc.
The arrows above and below each arc show the direction and value of the flow as indicated by the labelling procedure.
  1. Add a supersource S , a supersink T and appropriate arcs to the diagram above, and complete the labelling procedure for these arcs.
  2. Write down the value of the initial flow shown in Figure 1.
  3. Use Figure 2 below, the initial flow and the labelling procedure to find the maximal flow of 124 through this network. List each flow-augmenting path you use, together with its flow.
  4. Show your flow on the diagram below and state its value.
    \includegraphics[max width=\textwidth, alt={}, center]{0e86cb18-2c6e-49f1-b235-aa15eb83e260-4_967_1520_114_214}
  5. Prove that your flow is maximal.
    (2)
    (Total 14 marks)