AQA D1 2007 January — Question 8

Exam BoardAQA
ModuleD1 (Decision Mathematics 1)
Year2007
SessionJanuary
TopicGraph Theory Fundamentals

8
  1. The diagram shows a graph \(\mathbf { G }\) with 9 vertices and 9 edges.
    \includegraphics[max width=\textwidth, alt={}, center]{e47eb41e-0a4b-4865-a8ff-6c9978495ee0-08_188_204_411_708}
    \includegraphics[max width=\textwidth, alt={}, center]{e47eb41e-0a4b-4865-a8ff-6c9978495ee0-08_184_204_415_1105}
    \includegraphics[max width=\textwidth, alt={}, center]{e47eb41e-0a4b-4865-a8ff-6c9978495ee0-08_183_204_612_909}
    1. State the minimum number of edges that need to be added to \(\mathbf { G }\) to make a connected graph. Draw an example of such a graph.
    2. State the minimum number of edges that need to be added to \(\mathbf { G }\) to make the graph Hamiltonian. Draw an example of such a graph.
    3. State the minimum number of edges that need to be added to \(\mathbf { G }\) to make the graph Eulerian. Draw an example of such a graph.
  2. A complete graph has \(n\) vertices and is Eulerian.
    1. State the condition that \(n\) must satisfy.
    2. In addition, the number of edges in a Hamiltonian cycle for the graph is the same as the number of edges in an Eulerian trail. State the value of \(n\).