1. 1 IEEE Intelligent Systems, Special Issue on Social Learning, 2010

2. 2 Goal: analyzing how the networks evolve over time Models of social networks –networks follow power-law degree distribution, –have a small diameter –exhibit small-world structure and community structure Social networks is a function of time –The Obama networkThe Obama network Various Models have been studied –many tools have been built (example)example

3. 3 Dynamic Models The preferential attachment model: –assumes that new network nodes have a higher probability of forming links with high- degree nodes –creating a “rich-get-richer” effect Network diameter shrinks over time From: Leskovec et al. KDD’05

4. 4 Questions raised in this paper Studying network formation strategies –Microscopic level Graph Evolution Rules –Association rules –From current network configurations Predict future edges and nodes Rules –Old-old –Old-new –New-new

5. 5 Co-authorship Network http://www.arnetminer.org/viewperson.do?i d=486660&name=Qiang%20Yanghttp://www.arnetminer.org/viewperson.do?i d=486660&name=Qiang%20Yang http://academic.research.microsoft.com/Vi sualExplorer#435931http://academic.research.microsoft.com/Vi sualExplorer#435931

6. 6 Basic Concepts: Frequent Patterns and Association Rules (from J. Han) Itemset X={x 1, …, x k } Find all the rules X  Y with min confidence and support –support, s, probability Pr(X,Y) –confidence, c, conditional probability Pr(Y|X). Let min_support = 50%, min_conf = 50%: A  C (50%, 66.7%) C  A (50%, 100%) Customer buys diaper Customer buys both Customer buys beer Transaction-idItems bought 10A, B, C 20A, C 30A, D 40B, E, F

7. 7 Association Rules on Graphs First, we need to record time stamps on graphs –Nodes –Edges A large-degree node (label 3), which at time t is connected to four medium-degree nodes (label 2), at time t +1 will be connected to a fifth node. –The collaboration-rich researcher gets richer.

8. 8 G-span based GER Algorithm

9. 9 Example GER Rules

10. 10 Too many rules? Ranking

11. 11 Datasets

12. 12 Precision-Recall Curve

13. 13 Dataset Statistics

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