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From Erik Hatcher <e...@ehatchersolutions.com>
Subject Re: Lucene features
Date Sun, 07 Sep 2003 02:44:45 GMT
On Friday, September 5, 2003, at 07:45  PM, Leo Galambos wrote:
>> And for the second time today.... QueryFilter.  It allows narrowing 
>> the documents queried to only the documents from a previous Query.
>
>
> I guess, it would not be an ideal solution - the first query does two 
> things a) it selects a subset from the corpus; b) it assigns a 
> relevance to each document of this subset. Your solution omits the 
> second point. It implies, the solution will not return "good hit 
> lists", because you will not consider the information value of the 
> first query which was given to you by a user.

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.

Am I off base here?

> Thus I think, Chris would implement something more complex than 
> QueryFilter. If not, the results will be poorer than with the 
> commercial packages he may get. He could use a different model where 
> "AND" is not an associative operator (i.e. some modification of the 
> extended Boolean model). It implies, he would implement it in 
> Similarity.java (if I remember that class name correctly).

Right... but you'd still need the filtering capability as well, I would 
think - at least for performance reasons.

	Erik


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