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From Mark Miller <markrmil...@gmail.com>
Subject Re: Auto Slop
Date Mon, 02 Jul 2007 15:36:13 GMT
Examine your indexes and analyzers. The default slop is 0, which means 
allow 0 terms between the terms in the phrase. That would be an exact 
match. A slop of 1 is not the default and would allow a term movement of 
one position to match the phrase.

- Mark

Walt Stoneburner wrote:
> I just ran into an interesting problem today, and wanted to know if it
> was my understanding or Lucene that was out of whack -- right now I'm
> leaning toward a fault between the chair and the keyboard.
>
> I attempted to do a simple phrase query using the StandardAnalyzer:
> "United States"
>
> Against my corpus of test documents, I got no results returned, which
> surprised me.  I know it's in there.
>
> So, I ran this same query in Luke, and it also returned no results.
>
> Luke explains:
>  PhraseQuery: boost=1.0000, slop=0
>  pos[0,1]
>  Term 0: field='contents' text='united'
>  Term 1: field='contents' text='states'
>
> Now I know Lucene handles phrases, so I tried manually setting the
> slop to 1, given that there were two terms:  "United States"~1
>
> ...and suddenly I got the results I was expecting!
>
> In fact, after a little trial and error with larger phrases, I always
> get no results unless I *manually* specify at least slop value of the
> number of terms minus one.
>
> Isn't this supposed to be the default behavior if no slop is specified?
>
> Lucene's standard analyzer, which clear knows the number of terms,
> should be able to deduce the minimum slop amount.  Why must it be
> manually specified?
>
> Could I be missing some configuration setting, have a bad
> understanding of the query syntax, or is there a clever reason (like
> searching for encoding synonyms) that makes more sense as a default
> value for slop that I'm not seeing?
>
> Many thanks to all that unravel my confusion.
>
> -wls
>
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