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From "Terry Steichen" <te...@net-frame.com>
Subject Re: Query Term Questions
Date Wed, 21 Jan 2004 18:07:05 GMT
Morus,

Unfortunately, using positive boost factors less than 1 causes the parser to
barf the same as do negative boost factors.

Regards,

Terry

----- Original Message -----
From: "Morus Walter" <morus.walter@tanto-xipolis.de>
To: "Lucene Users List" <lucene-user@jakarta.apache.org>
Sent: Wednesday, January 21, 2004 10:54 AM
Subject: Re: Query Term Questions


> Erik Hatcher writes:
> > >
> > > TS==>I've not been able to get negative boosting to work at all.
Maybe
> > > there's a problem with my syntax.
> > > If, for example, I do a search with "green beret"^10, it works just
> > > fine.
> > > But "green beret"^-2 gives me a
> > > ParseException showing a lexical error.
> >
> > Have you tried it without using QueryParser and boosting a Query using
> > setBoost on it?  QueryParser is a double-edged sword and it looks like
> > it only allows numeric characters (plus "." followed by numeric
> > characters).  So QueryParser has the problem with negative boosts, but
> > not Query itself.
>
> He said he wants to have one term less important than others (at least
> that's what I understood).
> That's done by positive boost factors smaller than 1.0 (e.g. 0.5 or 0.1)
> and might be called 'negative boosting' (such as breking is a form of
> negative acceleration).
>
> If you use negative boost factors you would even decrease the score of
> a match (not only increase it less) and risk of ending with a negative
> score. I don't think that would be a good idea.
>
> Morus
>
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