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From "Robert Muir (JIRA)" <>
Subject [jira] Updated: (LUCENE-2091) Add BM25 Scoring to Lucene
Date Mon, 30 Nov 2009 04:31:23 GMT


Robert Muir updated LUCENE-2091:

    Attachment: persianlucene.jpg

otis attached is a graph i produced from the hamshahri corpus, comparing 4 different combinations
Lucene SimpleAnalyzer
Lucene SimpleAnalyzer + BM25
Lucene PersianAnalyzer
Lucene PersianAnalyzer + BM25

the hamshahri corpus contains standardized encoding of persian (i.e. the normalization filter
is a no-op).
so any analyzer gain is strictly due to "stopwords", although in persian i wouldn't call some
of these words.

this was mostly to show that the analyzer is actually useful, i.e. the scoring system can't
completely make up for lack of support like this.

> Add BM25 Scoring to Lucene
> --------------------------
>                 Key: LUCENE-2091
>                 URL:
>             Project: Lucene - Java
>          Issue Type: New Feature
>          Components: contrib/*
>            Reporter: Yuval Feinstein
>            Priority: Minor
>             Fix For: 3.1
>         Attachments: persianlucene.jpg
>   Original Estimate: 48h
>  Remaining Estimate: 48h
> describes an implementation of Okapi-BM25 scoring
in the Lucene framework,
> as an alternative to the standard Lucene scoring (which is a version of mixed boolean/TFIDF).
> I have refactored this a bit, added unit tests and improved the runtime somewhat.
> I would like to contribute the code to Lucene under contrib. 

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