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From Ahmet Arslan <iori...@yahoo.com>
Subject Re: SweetSpotSimilarity
Date Fri, 25 Jun 2010 17:09:46 GMT
> Would someone mind explaining how this differs from the
> DefaultSimilarity?

The difference is length normalization. Default one punishes long documents.

"Sweet one computes to a constant norm for all lengths in
the [min,max] range (the "sweet spot"), and smaller norm
values for lengths out of this range. Documents shorter or
longer than the sweet spot range are "punished""

Section 4.1 http://trec.nist.gov/pubs/trec16/papers/ibm-haifa.mq.final.pdf

> Also how would one replace the use of the DefaultSimilarity
> class with this
> one? I can't seem to find any such configuration in
> solrconfig.xml.


it is in schema.xml:

<similarity class="org.apache.lucene.search.SweetSpotSimilarity"/>



      

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