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https://issues.apache.org/jira/browse/LUCENE-965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12745608#action_12745608
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Hui Fang commented on LUCENE-965:
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Hello everyone,
We have re-implemented the retrieval functions in a very different way. The
main differences are (1) the average document length will not be computed in
the retrieval process as we did the previous implementation, which could make
the retrieval process more efficiently and (2) instead of modifying the
existing search related classes, we integrate the new retrieval functions
through two new classes, i.e., AXTermQuery and. AXTermScorer by extending
TermQuery and TermScorer classes. I think that the current implementation
addresses most concerns raised in this discussion threads.
The source codes and the updated reports of our implementation is now available
at http://www.ece.udel.edu/~hfang/LuceneAX.html. We have implemented two
slightly versions for lucene-2.4.1 and lucene-2.9-dev. We hope that the
implementation of the axiomatic retrieval function could be integrated in the
releases of the Lucene. Please feel free to let me know if you have any
questions or comments.
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
> Fix For: 3.0
>
> 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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