Edexcel D2 2007 June — Question 9

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

9. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{0e86cb18-2c6e-49f1-b235-aa15eb83e260-7_931_1651_196_118} \captionsetup{labelformat=empty} \caption{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.}
\end{figure}
  1. State the value of the initial flow.
  2. State the capacities of cuts \(\mathrm { C } _ { 1 }\) and \(\mathrm { C } _ { 2 }\). Figure 2 shows the labelling procedure applied to the above network.
  3. Using Figure 2, increase the flow by a further 19 units. You must list each flow-augmenting path you use, together with its flow.
  4. Prove that the flow is now maximal. \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{0e86cb18-2c6e-49f1-b235-aa15eb83e260-8_2146_1038_127_422} \captionsetup{labelformat=empty} \caption{Figure 2}
    \end{figure}