[
https://issues.apache.org/jira/browse/LUCENE-1534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12669750#action_12669750
]
Doug Cutting commented on LUCENE-1534:
--------------------------------------
I've always found "idf squared" an unhelpful description. We're computing a
dot-product of two vectors, the angle between them. Terms are dimensions. The
magnitude in each dimension is the weight of the term in a query or document.
Our heuristic for computing weights is (sqrt(tf)*idf)/norm. Put all that
together, and you do indeed get an "idf squared" factor in each addend of the
score. But if we feel that over-emphasizes terms with large idfs, then we
should not remove an idf factor from one vector, but rather rework our weight
heuristic, perhaps replacing idf with sqrt(idf), no?
> idf(t) is not actually squared during scoring?
> ----------------------------------------------
>
> Key: LUCENE-1534
> URL: https://issues.apache.org/jira/browse/LUCENE-1534
> Project: Lucene - Java
> Issue Type: Bug
> Components: Query/Scoring
> Affects Versions: 2.1, 2.2, 2.3, 2.3.1, 2.3.2, 2.4
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Minor
> Fix For: 2.9
>
>
> The javadocs for Similarity:
>
> http://lucene.apache.org/java/2_4_0/api/org/apache/lucene/search/Similarity.html
> show idf(t) as being squared when computing net query score. But I
> don't think it is actually squared, in looking at the sources? Maybe
> it used to be, eg this interesting discussion:
> http://markmail.org/message/k5pl7scmiac5wosb
> Or am I missing something? We just need to fix the javadocs to take
> away the "squared"...
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
