Mailing-List: contact lucene-user-help@jakarta.apache.org; run by ezmlm
Message-ID: <3F60D040.7040401@seznam.cz>
Date: Thu, 11 Sep 2003 21:42:56 +0200
From: Leo Galambos <Leo.G@seznam.cz>
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To: Lucene Users List <lucene-user@jakarta.apache.org>
Subject: Re: Lucene features
References: <3DC24860-E0DD-11D7-ADF3-000393A564E6@ehatchersolutions.com>
 <3F60B817.6040008@lucene.com>
In-Reply-To: <3F60B817.6040008@lucene.com>
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Doug Cutting wrote:

> Erik Hatcher wrote:
>
>> Yes, you're right.  Getting the scores of a second query based on the 
>> scores of the first query is probably not trivial, but probably 
>> possible with Lucene.  And that combined with a QueryFilter would do 
>> the trick I suspect.  Somehow the scores of the first query could be 
>> remembered and used as a boost (or other type of factor) the scores 
>> of the second query.
>
>
> Why not just AND together the first and second query?  That way 
> they're both incorporated in the ranking.  Filters are good when you 
> don't want it to affect the ranking, and also when the first query is 
> a criterion that you'll reuse for many queries (e.g., 
> language=french), since the bit vectors can be cached (as by 
> QueryFilter).


You probably missed the start of our discussion - we are talking about 
this: "q1 -> q2" which means "NOT q1 OR q2", versus "q2 -> q1" which 
means "q1 OR NOT q2". It causes the issue, and it also shows why you 
cannot use the simple "AND", because "q1 AND q2" != "NOT q1 OR q2" != 
"q1 OR NOT q2".

Leo

BTW: I didn't see the logic formulas for many years, so it is without 
any guarantee ;-)