1 1 Chenhao Tan, 1 Jie Tang, 2 Jimeng Sun, 3 Quan Lin, 4 Fengjiao Wang 1 Department of Computer Science and Technology, Tsinghua University, China 2 IBM TJ Watson Research Center, USA 3 Huazhong University of Science and Technology, China 4 Beijing University of Aeronautics and Astronautics, China Social Action Tracking via Noise Tolerant Time-varying Factor Graphs

2 Outline Motivation Approach Experiment Conclusion & Future Work

3 Motivation 500 million users the 3 rd largest “Country” in the world More visitors than Google Action: Update statues, create event More than 4 billion images Action: Add tags, Add favorites 2009, 2 billion tweets per quarter 2010, 4 billion tweets per quarter Action: Post tweets, Retweet

4 User Action in Social Networks Add photo to her favorites Post tweets on “Haiti Earthquake” Publish in KDD Conference TwitterFlickr Arnetminer

5 User Action in Social Networks Questions: -What factors influence you to add a photo into your favorite list? - If you post a tweet on “Haiti Earthquake”, will your friends retweet it or reply? Challenge: - How to track and model users’ actions? - How to predict users’ actions over time?

6 John Time t John Time t+1 Action Prediction ： Will John post a tweet on “Haiti Earthquake”? Action Prediction ： Will John post a tweet on “Haiti Earthquake”? Attributes: 1.Always watch news 2.Enjoy sports 3. …. Influence 1 Personal attributes 4 Dependence 2 Complex Factors Correlation 3

7 Problem formulation G t =(V t, E t, X t, Y t ) Input: G t =(V t, E t, X t, Y t ) t = 1,2,…T Output: F: f(G t ) ->Y t Nodes at time t Edges at time t Attribute matrix at time t Actions at time t

8 NTT-FGM Model Continuous latent action state Personal attributes Correlation Dependence Influence Action Personal attributes

9 How to estimate the parameters? Model Instantiation

10 Model Learning Extremely time costing!! Our solution: distributed learning (MPI)

11 Most Time-costing –Compute the gradients Distributed Learning

12 Data Set Baseline –SVM –wvRN (Macskassy, 2003) Evaluation Measure: Precision, Recall, F1-Measure ActionNodes#EdgesAction Stats Twitter Post tweets on “Haiti Earthquake” 7,521304,275730,568 Flickr Add photos into favorite list 8,721485,253 Arnetminer Issue publications on KDD 2,06234,9862,960 Experiment

13 Performance Analysis

14 Factor Contribution Analysis NTT-FGM: Our model NTT-FGM-I: Our model ignoring influence NTT-FGM-CI: Our model ignoring influence and correlation

15 Efficiency Performance

16 Conclusion Formally formulate the problem of social action tracking Propose a unified model: NTT-FGM to simultaneously model various factors Present an efficient learning algorithm and develop a distributed implementation Validate the proposed approach on three different data sets, and our model achieves a better performance

17 Thank you ！ QA? Data & Code: Welcome to our poster!