1. Challenge Problem: Link Mining Lise Getoor University of Maryland, College Park

2. Link Mining Data –Structured Input: Mining graphs and networks –Structured Output: Extracting entity and relationships from unstructured data Making use of Links –For ranking nodes –For collective classification of nodes Discovering Links –Predicting missing links –Discovering new kinds of links and relationships

3. Link Mining Tasks Node Centric –Labeling/ranking nodes (aka Collective Classification/PageRank) –Consolidating nodes (aka Entity Resolution) –Discovering hidden nodes (aka Group Discovery) Edge Centric –Labeling/ranking edges –Predicting the existence of edges –Predicting the number of edges –Discovering new relations/paths Graph/Subgraph Centric –Discovering frequent subpatterns –Generative models –Metadata discovery, extraction, and reformulation Reference: SigKDD Explorations Special Issue on Link Mining, December 2005.

4. The Link Mining Challenge Current research mostly focus on a single task, e.g., node ranking or link prediction In real data analysis scenarios, we need a mix of all of these capabilities Many potential domains: –Bioinformatics –Social network analysis –Citation Analysis –Fraud detection –….

5. Challenge Problem Requirements 1.Relevant to data mining and based on analysis of large volumes of data (including web, text, images, links, etc), preferably publicly available data. 2.Important and difficult so that its solution will advance the field and benefit the society 3.Interesting and exciting to attract researchers, public and press attention, and funding. This requires a simple and concise problem statement 4.The required domain knowledge should be relatively accessible. 5.Other groups are not actively working on this problem already

6. Domain Evangelists: “Goal to distribute free encyclopedia to every single person on the planet in their own language” Jimmy Wales Wikipedia founder Detractors::”Wikipedia has gone from a nearly perfect anarchy to an anarchy with gang rule.” Larry Sanger Wikipedia co-founder Know It All: Can Wikipedia Conquer Expertise? Stacy Schiff, New Yorker, July 31, 2006 Collaboratively edited user contributed encyclopedia Largest example of participatory journalism to date. Mantra: maintain a neutral point of view (NPOV) “Disaster is not too strong a word for wikipedia… the site is infested with moonbats” Eric Raymond, Open-source movement figure

7. Task #1: Descriptive Modeling Modeling Growth of Wikipedia

8. Task #2: User Classification Wiki Gnome: user that keeps a low profile, fixing typos, poor grammar and broken links Wiki Troll: disruptive user who persistently violates the site’s guidelines GnomeTroll vs.

9. Task #3: Text Classification Three Wikipedia Content Guidelines: 1. NPOV: represent views fairly and without bias 2. Verifiability 3. No original research

10. #4: Link Prediction/Completion Identify where links should exist As Wikipedia grows, it becomes harder for any given author to know about other relevant stuff they can/should link to from some article. Some method that could help with this (link suggestion, auto linking, etc.) would potentially be very useful. Evaluation: Generate a dataset by taking a given set of wikipedia pages, removing some of the existing links, and then see if a system could identify those places and suggest appropriate links.

11. Other Link Mining Tasks Trust/Reputation analysis –“Gives no privilege to those who know what they are talking about”, William Connolley, climate modeler and Wikipedia admin Social network analysis –Identification of communities Accuracy –Nature comparison with Britannica (4-3 error ratio) Misuse –Vandalism and self-promotion Coverage –Which areas aren’t covered, or are poorly covered/linked?

12. But none of these are grand challenges… According to wikipedia

13. The Wikipedia Grand Challenge The Wikipedia Test: Given a collection of entries constructed via participatory journalism (PJ) vs. link mining (LM), Can you distinguish between PJ and LM? Which is better? Evaluation: Via a panel of human experts Via page rank Solution will require a variety of integrated link mining capabilities

14. $$ Already Available… Hutter prize http://prize.hutter1.net/ http://prize.hutter1.net/ 50,000 € ≈ $64,000 http://en.wikipedia.org/wiki/The_64%2C0 00_Dollar_Question http://en.wikipedia.org/wiki/The_64%2C0 00_Dollar_Question