[jira] Commented: (LUCENE-1302) explain should not mask negative scores

["Doron Cohen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-1302?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12603869#action_12603869 ] 

Doron Cohen commented on LUCENE-1302:
-------------------------------------

Another option is for BTQ to return a ComplexExplanation instead of Explanation and setMatch(true) if the score is non-zero.
Still it would disturb to declare a "negative score" as a "match".

> explain should not mask negative scores
> ---------------------------------------
>
>                 Key: LUCENE-1302
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1302
>             Project: Lucene - Java
>          Issue Type: Bug
>          Components: Query/Scoring
>            Reporter: Doron Cohen
>            Assignee: Doron Cohen
>            Priority: Minor
>             Fix For: 2.4
>
>         Attachments: lucene-1302-explain-negative.patch
>
>
> Explanation.isMatch() returns false for 0 or negative scores. 
> Hence negative scores are omitted from the explanation.
> This causes, when using e.g. BoostingTermQuery with negative boosts, a difference between the collected doc score and the score shown by explain().  
> A word on the usage of this - BTQ with negative boosts is useful for "punishing" documents for containing a term. It also allows all sorts of tricks with multiplying query boost by the BTQ boost, so you get a positive score if both boosts have the same sign but negative otherwise. - I am sure there other uses as well.

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