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From: "Uwe Schindler" <uwe@thetaphi.de>
To: <java-user@lucene.apache.org>,
	<paul_t100@fastmail.fm>
References: <4F23C0B9.2040401@fastmail.fm>
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In-Reply-To: <4F23C76A.6060700@fastmail.fm>
Subject: RE: Does Fuzzy Search scores the same as Exact Match
Date: Sat, 28 Jan 2012 11:31:26 +0100
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-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de


> -----Original Message-----
> From: Paul Taylor [mailto:paul_t100@fastmail.fm]
> Sent: Saturday, January 28, 2012 11:01 AM
> Cc: java-user@lucene.apache.org
> Subject: Re: Does Fuzzy Search scores the same as Exact Match
> 
> On 28/01/2012 09:36, Uwe Schindler wrote:
> > Hi,
> >
> >> -----Original Message-----
> >> From: Paul Taylor [mailto:paul_t100@fastmail.fm]
> >> Sent: Saturday, January 28, 2012 10:33 AM
> >> To: 'java-user@lucene.apache.org'
> >> Subject: Does Fuzzy Search scores the same as Exact Match
> >>
> >> All things being equal does a fuzzy match give the same score as an
> >> exact match.
> >> i.e if I do a search for farmin and it matches two docs one on term
> > farmin, the
> >> other on term farming, will it score farming higher or score both the
> >> same
> > ?
> >
> > YES, depends on the Fuzzy configuration (rewrite method,...), but the
> > default does so!
> >
> > Uwe
> >
> >
> So how do I change it, seems like a funny default to have.

Maybe I was not clear, it should score "farming" higher than "farmin" by
default, but the default rewrite mode also takes TF/IDF into account (in
addition). You can change that by a different rewrite method:

The default is: http://goo.gl/JhHOA (which combines the standard vector
model with additionally boosting exact matches - we have that for backwards
compatibility only, its not what most users expect)

The better one is: http://goo.gl/0eJ47, which does not take TF/IDF into
account and only boosts by levensthein distance.

You can disable fuzzy boosting altogether:
Additionally http://goo.gl/VWlkW provides two other scoring models (TF/IDF
only, no boosting - or constant score at all)

Uwe


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