1. Hui Fang (ACL 2008) presentation 2009/02/04 Rick Liu

2. Intro.  “Re”-examine?  None of the previous studies is able to show significant performance improvement through query expansion using information only from manually created lexical resources.  Re-examine the problem of query expansion using lexical resources in recently proposed axiomatic framework.

3. Intro.  Axiomatic framework?  Hui Fang & ChengXiang Zhai proposed. (SIGIR2005)  Anatomize existing retrieval functions such as Okapi, Dirichlet Prior, etc. and derive a new retrieval formula.

4. Axiomatic Retrieval Model

6. Comparison  Fang & Zhai SIGIR2006 (Semantic Term Matching in …)  Co-occurrence, document frequency, etc.  Fang ACL2008(this)  Lexical resources

7. Lexical Resources  WordNet  Dependency-based thesaurus.

8. Similarity Function  WordNet  Definition * 1  Relation * 5  Dependency-based thesaurus.  Dependency * 1

9. WordNet : Definition

10. WordNet : Relation  Synonym : X and Y are interchangeable  Hypernym : Y is a kind of X  Hyponym : X is a kind of Y  Holonym : Y is a part of X  Meronym : X is a part of Y

11. Dependency-based Thesaurus

12. Combination

14. Experiment Design  6 TREC Collections  Only stemming with Porter’s stemmer.

15. Experiment Design  6 TREC Collections  Only stemming with Porter’s stemmer.

16. Experiment Design  WordNet 3.0  Lemur Toolkit  TrecWN library  C++ functions as WordNet Interface  Evaluation  MAP  gMAP( geometric ) : emphasizes the performance of difficulty queryies.

17. Experiment Results

20.  Binary  POS

21. Experiment Results

22.  Better than relation  Smaller coverage

23. Experiment Results

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