CS 765 Complex Networks
Network Lab 2
Due on Wednesday Sep 27, 2017 at 1 pm
Bipartite Graphs (5 points)
For this part, you may look at Pajek tutorial.
- Download the file actorsandmovies.net
- Open it in Pajek. A report window should pop up confirming that the graph has been read.
- This is a 2 mode network containing two classes of nodes, actors and movies. Create a 2-mode partition.
- Visualize the network. The two classes of nodes should be colored differently. If labels are not shown, add them. Include an image of layout.
- Transfrom the network into a one-mode network. Include an image.
- Qualitatively compare the structure of the 2-Mode to the 1-Mode network of actors. Is there a loss of information?
- Show the weights on each edge. What do the values represent?
- Compute the unweighted degree of each node. How is the degree represented?
- Add the vector value to each vertex (it will be the degree/(max possible degree)). Include an image.
- Who are the most important actors using degree centrality?
- How does the boundary of the network (i.e. who is included) affect who is found to be most central?
- Load the file actorsandmoviesWithGere.net. It contains one extra actor, Richard Gere. Repeat the above procedure.
- In the 1-mode network of actors, is there a change in who is most central?
- What does this tell you about biases and boundaries in sample selection?
- Remove all edges between actors who have costarred in fewer than 3 movies. Which actors comprise the central core of this network?
Social Network (5 points)
For this assignment you will use friend circle data.
Submitting your files
- Do an energy layout of the network, using the degree partition and either closeness or betweenness as the vector. Include an image.
- Who is the most central node in the network by degree, closeness and betweenness?
- Point out 3 vertices whose centrality scores differ (e.g. high betweenness but medium closeness) and explain from their position in the network why it happens.
- Identify a node with high betweenness that you could afford to remove without disconnecting other vertices from that component.
Create a second network that excludes that person. Recompute betweenness for everyone remaining in the network. Include an image.
- Point out 2 particular vertices and their position in the network. Discuss why their betweenness centrality score did or did not change.
- Point out 1 vertex (if it exists) whose closeness centrality suffers as a result.
- Imagine you are a newcomer who wants to not only be friends with you, but occupy a central position in your network.
You only have time to make 2 new acquaintances out of your network of friends. Which 2 would you choose to maximize your closeness centrality?
- Add yourself to the network and compute your closeness (or you could alter the data file).
Which 2 vertices would you connect to to maximize your betweenness score (what is your betweenness?).
Submission of your homework is via WebCampus.
You must submit all the required files in a single pdf document containing all the answers.
Acknowledgement: The assignment is modified from Lada Adamic.