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https://issues.apache.org/jira/browse/LUCENE-3220?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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David Mark Nemeskey updated LUCENE-3220:
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Attachment: LUCENE-3220.patch
EasySimilarity now computes norms in the same way as DefaultSimilarity.
Actually not exactly the same way, as I have not yet added the discountOverlaps
property. I think it would be a good idea for EasySimilarity as well (it is for
phrases, right), what do you reckon?
I also wrote a quick test to see which norm (length directly or 1/sqrt) is
closer to the original value and it seems that the direct one is usually much
closer (RMSE is 0.09689688608375747 vs 0.23787634482532286). Of course, I know
it is much more important that the new Similarities can use existing indices.
> Implement various ranking models as Similarities
> ------------------------------------------------
>
> Key: LUCENE-3220
> URL: https://issues.apache.org/jira/browse/LUCENE-3220
> Project: Lucene - Java
> Issue Type: Sub-task
> Components: core/query/scoring, core/search
> Affects Versions: flexscoring branch
> Reporter: David Mark Nemeskey
> Assignee: David Mark Nemeskey
> Labels: gsoc, gsoc2011
> Attachments: LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch,
> LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch,
> LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch,
> LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch,
> LUCENE-3220.patch, LUCENE-3220.patch, LUCENE-3220.patch
>
> Original Estimate: 336h
> Remaining Estimate: 336h
>
> With [LUCENE-3174|https://issues.apache.org/jira/browse/LUCENE-3174] done, we
> can finally work on implementing the standard ranking models. Currently DFR,
> BM25 and LM are on the menu.
> Done:
> * {{EasyStats}}: contains all statistics that might be relevant for a
> ranking algorithm
> * {{EasySimilarity}}: the ancestor of all the other similarities. Hides the
> DocScorers and as much implementation detail as possible
> * _BM25_: the current "mock" implementation might be OK
> * _LM_
> * _DFR_
> * The so-called _Information-Based Models_
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