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MTH 607 Graph Theory Lab 7

  1. For the graphs below:
    G1 G2 G3
    1. Find all cut vertices.
    2. Find all bridges
    3. Find the blocks of the graphs.
    4. Trace through the block finding algorithm and indicate the P value of each vertex, its parent and block.

    1. (Book 5.12) If a graph contains 3 blocks and k cut vertices, what are the possible values of k?
    2. Show that if a connected graph G with k blocks B1 . . . Bk then
      n(G) = [ Σk i=1 n(Bi) ] - k + 1
      Where n(X) is the number of points in X.

    1. Consider the statement P:
      If e is a cut edge of a graph then one of the vertices of e is a cut vertex.
    2. Give a counterexample to show that the P is false.
    3. Think of a condition to add to this statement which would make P true.
    4. Prove the amended statement.

  2. The graph Q3 below is both 3-connected and 3-edge connected.
    1. Find three internally disjoint paths between
      1. 000 and 011;
      2. 000 and 101.

    2. Find three edge disjoint disjoint paths between.
      1. 000 and 011;
      2. 000 and 101.