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Event summarization using tweets
- 1. Event Summarization using Tweets Deepayan Chakrabarti and KunalPunera Yahoo!Research
- 2. Abstract For some highly structured and recurring events, such as sports, it is better to use more sophisticated techniques to summarize the relevant tweets. A solution based on learning the underlying hidden state representation of the event via Hidden Markov Models.
- 3. Introduction one-shot events Have “structure” or are long-running (a)the most recent tweets could be repeating the same information about the event (b)most users would be interested in a summary of the occurrences in the game so far.
- 4. Introduction Our goal：to extract a few tweets that best describe the chain of interesting occurrences in that event A 1. 2. two-step process： Segment the event time-line pick key tweets to describe each segment
- 5. Introduction challenges ： Events are typically “bursty” Separate sub-events may not be temporally far apart Previous instances of similar events are available. Tweets are noisy Strong empirical results.
- 6. Characteristics of Sports Coverage in Tweets
- 7. Characteristics of Sports Coverage in Tweets
- 8. Characteristics of Sports Coverage in Tweets Some 1. 2. issues of this data: sub-events are marked by increased frequency of tweets. Boundaries of sub-events also result in a change in vocabulary of tweets.
- 9. Algorithms Baseline: SUMMALLTEXT associate with each tweet a vector of the TF-logIDF of its constituent words Cosine distance Select those tweets which are closest to all other tweets from theevent.
- 10. Algorithms
- 11. Algorithms Several 1. 2. defects： O ( |Z|2) computations heavily biased towards the most popular sub-event
- 12. Algorithms Baseline: 1. 2. SUMMTIMEINT Split up the duration into equal-sized time intervals Select the key tweets from each interval Two 1. 2. extra parameters: a segmentation TS of the duration of the event into equal-time windows the minimum activity threshold l
- 13. Algorithms
- 14. Algorithms Defects: Burstiness of tweet volume: Multiple sub-events in the same burst: “Cold Start” :
- 15. Algorithms Our Approach: SUMMHMM BACKGROUND ON HMMS: N states labeled S1 ,…, SN , A set of observation symbols v1 ,…, vM bi(k) a ij πi
- 16. Algorithms Each state: one class of sub-events The symbols: the words used in tweets The variation in symbol probabilities across different states: the different “language models” used by the Twitter users The transitions between states models the chain of sub-events over time
- 17. Algorithms Our Modifications OUTPUTS PER TIME – STEP: a multiset of symbols DETECTING BURSTS IN TWEET VOLUME: COMBINING INFORMATION FROM MULTIPLE EVENTS
- 18. Algorithms three sets of symbol probabilities: (1)θ( s ) , which is specific to each state but is the same for all events, (2) θ( sg ) , which is specific to a particular state for a particular game (3) θ( bg ) , which is a background distribution of symbols over all states and games.
- 19. Algorithms Algorithm Summary Input: multiple events of the same type Learns the model parameters that bestfit the data. （EM algorithm） the optimal segmentation （standard V iterbi algorithm）
- 21. Algorithms
- 22. Experiments Experimental Setup professional American Football Sep 12th, 2010 to Jan 24th, 2011 over 440K tweets over 150 games for an average of around 1760 tweets per game.
- 23. Experiments MANUAL GROUND TRUTH CONSTRUCTION . Each output tweet was matched with the happenings in the game and labeled as Comment-Play , Comment-Game , or Comment-General .
- 24. Experiments Play-by-Play Performance RECALL PRECISION Summary Construction
- 25. EVALUATION AT OPERATING POINT .
- 29. conclusion We proposed an approach based on learning an underlying hidden state representation of an event .
- 31. ABSTRACT Traditional summarization techniques only consider text information. We study how user influence models, which project user interaction information onto a Twitter context tree, can help Twitter context summarization within a supervised learning framework.
- 32. INTRODUCTION A Twitter context tree is defined as a tree structure of tweets which are connected with reply relationship, and the root of a context tree is its original tweet. two types of user influence models, called pair-wise user influence model and global user influence model. Granger Causality influence model PageRank algorithm
- 33. TWITTER CONTEXT TREE ANALYSIS The temporal growth of the Twitter context tree
- 34. TWITTER CONTEXT TREE ANALYSIS Whether the tree structure can help the summarization task
- 35. USER INFLUENCE MODELS Granger Causality Influence Model A time series data x is to Granger cause another time series data y ,If and only if regressing for y in terms of both past values of y and x is statistically significantly more accurate than regressing for y in terms of past values of y only. Let
- 36. USER INFLUENCE MODELS Lasso-Granger method Lag ( X,T )to denote the lagged version of data X ; FullyConnectedFeatureGraph ( X ) denotes the fully connected graph defined over the features; Lasso ( y, Xlag )denotes the set of temporal variables receiving a non-zero co-efficient by the Lasso algorithm.
- 38. USER INFLUENCE MODELS Pagerank Influence Model For each user u , it has a directed edge to each user v if u has a reply or a retweet to v ’s tweet and we can have a global user graph G .
- 39. SUMMARIZATION METHOD Text-based TFIDF Signals
- 40. SUMMARIZATION METHOD Popularity Signals Number of replies, number of retweets, and number of followers for a given tweet’s author.
- 41. SUMMARIZATION METHOD Temporal 1. 2. Signals fit the age of tweets in a context tree into an exponential distribution. for each tweet, we compute its temporal signal as the likelihood of sampling its age from the fitted exponential distribution.
- 42. Supervised Learning Framework Gradient algorithm Boosted Decision Tree(GBDT)
- 43. EDITORIAL DATA SET 10 Twitter context trees from March 7th to March 20th,2011 4 are initiated by Lady Gaga 6 are initiated by Justin Bieber 1. read the root tweet 2. Scans through all candidate tweets 3. Selects 5 to 10 tweets
- 54. CONCLUSION User influence information is very helpful to generate a high quality summary for each Twitter context tree. All signals are converted into features, and we cast Twitter context summarization into a supervised learning problem.