Watson presentation

Joseph Orilogbon Luis Lasierra

Bin Shen

5/12/14 Semantic Technologies in IBM Watson 1

Discovering why Topics are Trending on Twitter


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*We set out to explain Why Topics are Trending on Twitter

*Main approach to achieve this was to use summarization.


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*News break on Twitter

*Twitter -> prominent way of expressing opinions on the Internet

*Why people are talking about a particular topic in a given location

*Commercial interest


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*Summarization of trending topics on Twitter

*Categorization of Topics; and

*Named-Entity Extraction for Trending topics


*http://whytrend.intelworx.com


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*Speech Act Guided Summarization

*Phrase Ranking using MLE

*Phrase Extraction using POS filtering

*Salience Score of Extracted Phrases

*Summary generation using templates


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*Speech Acts include : Statement [sta], Question [que], Comment [com], Suggestion [sug] and Miscellaneous [mis]

*Speech Act classification is a multiclass problem *K-Nearest neighbors approach was used for classification.


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*Extracted Phrase were Ranked using the following equation

*𝑆𝑆𝑆𝑆𝑆 𝑃 = log 𝐿(𝑤𝑤𝑤𝑤𝑤 𝑖𝑖 𝑃 𝑎𝑤𝑎 𝑖𝑖𝑤𝑎𝑖𝑎𝑖𝑤𝑎𝑖𝑖) 𝐿(𝑤𝑤𝑤𝑤𝑤 𝑖𝑖 𝑃 𝑎𝑤𝑎 𝑤𝑎𝑖𝑎𝑖𝑤𝑎𝑖𝑖)

*Dependence/Independence measured based on using a background twitter corpus built from 550,000 tweets

*For lengths 1 to L, we extract the top 50 phrases. *L is a model parameter for maximum phrase length


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*Extracted N-Grams are only useful if they are: *Nouns or Noun Phrase

*Verbs or a Verb-Centered Phrase

*After Extracting N-Grams, those not matching the required patterns were filtered out using RegEx on their POS Tag Pattern

*Tagging was done before extracting N-Grams to give the tagger the proper context.

*Different patterns are suitable for different Speech-Act


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*This is another round of ranking of phrases based on how “Salient” they are within the given topic

*Salience Score is given as 𝑆𝑆 𝑁𝑔𝑖 = 𝐺𝑆 𝑁𝑔𝑖 × 𝑁𝑖 *𝑁𝑖 is the length of N-Gram 𝑁𝑔𝑖

*𝐺𝑆 𝑁𝑔𝑖 is a graph score obtained by iterating over a graph G=(V, E), where V is the set of N-grams, and E is a set edges weighted based on the number of times the N-Grams co-occur.


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*Greedy strategy was used to select most salient phrases

*Phrases were used to fill templates

*Speech acts used to describe how people are talking about the salient phrases.

*Redundant phrases were detected using Jaccard Coefficient of 0.275


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*The main reference is Zhang et. al, 2013

*Speech Acts were not used for filtering out tweets

*Two rounds of POS filtering was done, as supposed to one in the original paper

*Greedy strategy was used as opposed to Round-robin used in the original paper

*Representative tweets were also presented to give the user some sense of context.


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*Speech Act Training Data Set (Liu, et. al), for speech act classification

*Sentiment 140 dataset, for background corpus

*TweetMotif dataset (O’Connor et. al, 2010) for background corpus.

*Twitter NLP (Gimpel et al) for POS tagging

*Tweets collected via Twitter API for testing summarization model, see examples on site.


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*Entity Extraction *Preprocessing, proper nouns extraction

*Google Knowledge Graph: Freebase

*Categorization *uClassify API

*Extract highest ranking category


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*Front end *Auto-detection/manual selection of location *Displays trending topics *Sends requests to server to analyze topics

*Back end *Tweets retrieval *Analysis using model of summarization *Send results to Freebase and uClassify APIs *Caches result


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*Front end: HTML 5, JS, Google Maps API, Angular JS, JQuery

*Backend: Java / Play framework and MySQL database

*Hosted on AWS


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*Asked users to provide feedback on results

*Questions covered all 3 parts of the project

*Got 19 responses as at the time of making this slide,


Avg = 3.89

Avg = 4.00


Avg = 4.21

Avg = 3.84


Avg = 4.16


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* Liu, Fei, Yang Liu, and Fuliang Weng. "Why is SXSW trending?: exploring multiple text sources for Twitter topic summarization." 2011. 66--75.

* OConnor, Brendan, Michel Krieger, and David Ahn. "TweetMotif: Exploratory Search and Topic Summarization for Twitter." 2010.

* Zhang, Renxian, Wenjie Li, Dehong Gao, and You Ouyang. "Automatic Twitter Topic Summarization With Speech Acts." Audio, Speech, and Language Processing, IEEE Transactions on (IEEE) 21 (2013): 649--658.

* Nathan Schneider, Brendan O'Connor, Dipanjan Das, Daniel Mills, Jacob Eisenstein, Michael Heilman, Dani Yogatama, Jeffrey Flanigan, and Noah A. Smith. Part-of-Speech Tagging for Twitter: Annotation, Features, and Experiments Kevin Gimpel, In Proceedings of ACL 2011.

* Abeel, T.; de Peer, Y. V. & Saeys, Y. Java-ML: A Machine Learning Library, Journal of Machine Learning Research, 2009, 10, 931-934


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*Tweets under a topic are loosely grouped together, sometimes not sharing too much in common.

*Low performance with Speech-Act Classification

*Detection of Main entity

*Normalization of tweets could at times result in weird results

*Limits on Twitter API 180 search queries/user/application/15 minutes


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*Real-time indexing of tweets before they start trending, using Lucene/ES or other full-text engines.

*Detection of sentence overlap in the selected phrases

*Detecting redundancies semantically.

*Different templates for various topic categories.


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