Maggy,
On javauser@lucene.apache.org there is normally a higher chance of
getting a response.
You may have missed this:
http://lucene.apache.org/java/docs/scoring.html
Your analysis below is correct, only a few points need to be added:
 the coordination factor, which favours more matching clauses
(for prefix queries normally no coordination is used),
 your examples are nested boolean queries, so all this applies on
each level, and
 the idf computation is a bit more involved, see the reference above.
Regards,
Paul Elschot
On Tuesday 03 July 2007 01:38, #MAGGY ANASTASIA SURYANTO# wrote:
> Hi all,
>
> I would like to clarify my understanding of the way Lucene score boolean
queries, in relation with +/ clause attributes (required and optional) as
well as OR and AND operators.
>
> After looking at the BooleanScorer source core, the following is my
understanding on the scoring:
> 1. OR is translated into " " (optional) and AND is translated into
"+" (required) by queryParser
> so, is it true that
> (t1 t2 t3) AND (t4 t5 t6) OR (t7 t8 t9) is parsed by queryParser into the
following boolan query
> +(t1 t2 t3) +(t4 t5 t6) (t7 t8 t9)
>
> 2. using default similarity, a score of a document score(q,d) is the
summation of the tf, idf measure of the terms in q that appear in d.
>
> 3. Score of a document w.r.t BooleanClause, BC (score(BC,d)) is the sum of
score of the document w.r.t sall sub clauses of BC.
>
> 4. no difference in treating "+" clauses and " " clauses in scoring (i.e.
their scorer.score() are summed up together to produce the total score of
their parent' score), however, the addition of the scores of " " clauses are
delayed until all "+" are matched by the documents. If not all "+" mare
matched, the document is not retrieved.
> C1 C2 C3 C4
> q = +{+(t1 t2 t3) +(t4 t5 t6) (t7 t8 t9)} {t10 t11 t12}
>
> assuming a document,d match C1 and C2, the s(q,d) = sum(sum(s(C1,d) +
s(C2,d) + s(C3, d)), s(C4,d))
>
> Please let me know whether the above are true. In case there are something I
miss to understand the scoring of booleanScorer, please let me know.
>
>
> best regards
>
> maggy
>
>
>
>
