AW: Poor Lucene Ranking for Short Text

[Michael Hartmann <mi...@web.de>]

Hi Kevin,

Seem like you have some knowledge about the lenghtNorm value in Lucene.
Comparing it to the formula in "Modern Information Retrieval" does it sum up
the denominator sqrt((sum(tf_d*idf_t)²)) * sqrt((sum(tf_q*idf_t)²))

Just a quick note is ok.

Besides that could you invite me to rojo. There beta status seem to be quite
long.

Thanks
Michael

| -----Ursprüngliche Nachricht-----
| Von: 
| lucene-user-return-10902-michael.hartmann=web.de@jakarta.apach
| e.org 
| [mailto:lucene-user-return-10902-michael.hartmann=web.de@jakar
| ta.apache.org] Im Auftrag von Kevin A. Burton
| Gesendet: Mittwoch, 27. Oktober 2004 22:48
| An: Lucene Users List
| Betreff: Re: Poor Lucene Ranking for Short Text
| 
| Daniel Naber wrote:
| 
| > (Kevin complains about shorter documents ranked higher)
| >
| >This is something that can easily be fixed. Just use a Similarity 
| >implementation that extends DefaultSimilarity and that overwrites
| >lengthNorm: just return 1.0f there. You need to use that 
| Similarity for 
| >indexing and searching, i.e. it requires reindexing.
| >  
| >
| What happens when I do this with an existing index? I don't 
| want to have to rewrite this index as it will take FOREVER
| 
| If the current behavior is all that happens this is fine... 
| this way I can just get this behavior for new documents that 
| are added.
| 
| Also... why isn't this the default?
| 
| Kevin
| 
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