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https://issues.apache.org/jira/browse/LUCENE-965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12515514
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Hui Fang commented on LUCENE-965:
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Hi Grant and Doron, 

Thank you very much for your comments! They are very useful. I agree that it 
would be interesting to evaluate this in the context of Lucene-836, which is a 
very nice idea. Actually, my advisor and I also discussed that we could put 
some evaluation scripts in Lucene so that others could easily evaluate the 
retrieval performance. Hope that Lucene-836 would be finalized soon, and please 
let me know if there is anything I could help. 

Regarding to the speed, the axiomatic retrieval function should have the same 
computatlonal complexity as the default function if we could compute the 
average document length at the indexing time instead of search time.  As Doron 
pointed out, my current implementation is not optimal, I will fix this problem 
and other svn related problems as soon as possible, and resubmit a new patch. 

Thanks,
-Hui

 

> Implement a state-of-the-art retrieval function in Lucene
> ---------------------------------------------------------
>
>                 Key: LUCENE-965
>                 URL: https://issues.apache.org/jira/browse/LUCENE-965
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>    Affects Versions: 2.2
>            Reporter: Hui Fang
>         Attachments: axiomaticFunction.patch
>
>
> We implemented the axiomatic retrieval function, which is a state-of-the-art 
> retrieval function, to 
> replace the default similarity function in Lucene. We compared the 
> performance of these two functions and reported the results at 
> http://sifaka.cs.uiuc.edu/hfang/lucene/Lucene_exp.pdf. 
> The report shows that the performance of the axiomatic retrieval function is 
> much better than the default function. The axiomatic retrieval function is 
> able to find more relevant documents and users can see more relevant 
> documents in the top-ranked documents. Incorporating such a state-of-the-art 
> retrieval function could improve the search performance of all the 
> applications which were built upon Lucene. 
> Most changes related to the implementation are made in AXSimilarity, 
> TermScorer and TermQuery.java.  However, many test cases are hand coded to 
> test whether the implementation of the default function is correct. Thus, I 
> also made the modification to many test files to make the new retrieval 
> function pass those cases. In fact, we found that some old test cases are not 
> reasonable. For example, in the testQueries02 of TestBoolean2.java, 
> the query is "+w3 xx", and we have two documents "w1 xx w2 yy w3" and "w1 w3 
> xx w2 yy w3". 
> The second document should be more relevant than the first one, because it 
> has more 
> occurrences of the query term "w3". But the original test case would require 
> us to rank 
> the first document higher than the second one, which is not reasonable. 

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