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https://issues.apache.org/jira/browse/LUCENE-2959?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13113977#comment-13113977
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Robert Muir commented on LUCENE-2959:
-------------------------------------
{quote}
I saw that you didn't change the default implementation of lucene for coding
the document length which is used for ranking in language models (one byte for
coding the document length together with boosting). Why did you decide that?
{quote}
So that you can switch between ranking models without re-indexing.
{quote}
It is just that I'm concerned with the effect of using an inaccurate document
length on results quality. Did you check this issue?
{quote}
I ran experiments on this a long time ago, the changes were not statistically
significant.
But, there is an issue open to still switch norms to docvalues fields, for
other reasons: LUCENE-3221
{quote}
In addition - do you know about intentions to implement some more advanced
ranking models (such as relevance models, mrf) in the near future?
{quote}
No, there won't be any additional work on this issue, GSOC is over.
> [GSoC] Implementing State of the Art Ranking for Lucene
> -------------------------------------------------------
>
> Key: LUCENE-2959
> URL: https://issues.apache.org/jira/browse/LUCENE-2959
> Project: Lucene - Java
> Issue Type: New Feature
> Components: core/query/scoring, general/javadocs, modules/examples
> Reporter: David Mark Nemeskey
> Assignee: Robert Muir
> Labels: gsoc2011, lucene-gsoc-11, mentor
> Fix For: flexscoring branch, 4.0
>
> Attachments: LUCENE-2959.patch, LUCENE-2959.patch,
> LUCENE-2959_mockdfr.patch, LUCENE-2959_nocommits.patch,
> implementation_plan.pdf, proposal.pdf
>
>
> Lucene employs the Vector Space Model (VSM) to rank documents, which compares
> unfavorably to state of the art algorithms, such as BM25. Moreover, the
> architecture is
> tailored specically to VSM, which makes the addition of new ranking functions
> a non-
> trivial task.
> This project aims to bring state of the art ranking methods to Lucene and to
> implement a
> query architecture with pluggable ranking functions.
> The wiki page for the project can be found at
> http://wiki.apache.org/lucene-java/SummerOfCode2011ProjectRanking.
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