finding similar questions in large question and answer archives
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Finding Similar Questions in Large Question and Answer Archives
Jiwoon Jeon, W. Bruce Croft and Joon Ho Lee
Retrieval Models for Question and Answer Archives
Jiwoon Jeon, W. Bruce Croft and Xiaobing Xue
PresenterSawood Alam <salam@cs.odu.edu>
Finding Similar Questions in Large Question and Answer Archives
Jiwoon Jeon, W. Bruce Croft and Joon Ho LeeCenter for Intelligent Information Retrieval, Computer Science
DepartmentUniversity of Massachusetts, Amherst, MA 01003
[jeon,croft,joonho]@cs.umass.edu
CIKM '05, Proceedings of the 14th ACM Conference on Information and Knowledge Management, 2005
Introduction
• Q&A systems quickly build large archives– Naver, a popular Korean search site gets 25,000+
questions per day• Great linguistic resource• Answering questions from the archive before a
human response appear
Q&A Over Usual Search
• Opinion or summary• Direct answers rather than relevant documents• Search in collection of questions associated
with answers• Lexical similarity vs. semantic similarity– Is downloading movies illegal?– Can I share a copy of a DVD online?
Solving Word Mismatch Problem
• Knowledge database (machine readable dictionaries) – unreliable performance
• Manual rules or templates – hard to scale• Statistical technique – most promising– Requires large training data set
Question and Answer Archive
• Average lengths (words)• Title: 5.8• Body: 49• Answer: 179
Relevance Judgments
• Eighteen different retrieval results (varying retrieval algorithms)– Query likelihood, Okapi BM25 and overlap
coeficient• Top 20 Q&A pairs from each retrieval result• Manual judgment• Correctness of answer was ignored• Manual browsing for missing relevant Q&A
pairs
Field Importance
Generation of Training Sample
• LM-HRANKSim(A, B) = (1/r1 + 1/r2) / 2
Where:• Answer A retrieves B at
rank r1
• Answer B retrieves A at rank r2
Word Translation Probabilities
Experiments and Results
Examples and Analysis
Retrieval Models for Question and Answer Archives
Jiwoon JeonGoogle, Inc. Mountain View, CA 94043, USA
jjeon@google.comW. Bruce Croft and Xiaobing Xue
Center for Intelligent Information Retrieval, Computer Science DepartmentUniversity of Massachusetts, Amherst, MA 01003
[croft,xuexb]@cs.umass.edu
SIGIR '08, Proceedings of the 31st annual international ACM SIGIR conference on Research and development in information
retrieval, 2008
Introduction
• Word mismatch problem• Focus on translation based approach• Explanation of poor performance of pure IBM
model vs. query-likelihood language model• Proposed a mixed model– Query part: translation based language model– Answer part: query likelihood language model
LM vs. IBM model 1
Question Part
Answer Part
• Gamma = 0 : translation based (for question part)• Gamma = 1 : query likelihood LM (for answer part)• Beta = 0 : combination model
Word-to-Word Translation Probability
• Word “cheat” in question– “trust”, “forgive”, “dump” and “leave” etc. in answer
• Word “cheat” in answer– “husband” and “boyfriend” etc. in question
• All these words are useful to attack word mismatch problem– Combined probability used: P(Q|A) and P(A|Q)
Examples
Experimental Results
Conclusions
• Translation based language model for query part and QL language model for answer part
• Experiment done on a Q&A web service where people answer others questions
• Future work– Testing effect of proposed model on FAQ archives– Yahoo! Answers collection– Phrase based machine translation rather than
word based translation
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