[jira] [Comment Edited] (LUCENE-329) Fuzzy query scoring issues

["Adrien Grand (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14540069#comment-14540069 ] 

Adrien Grand edited comment on LUCENE-329 at 5/12/15 3:44 PM:
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It's not correct to do {{maxTtf = Math.max(ttf, maxTtf)}} because the ttf can sometimes be -1, so it would rather need to be something like {{maxTtf = ttf == -1 || maxTtf == -1 ? -1 : Math.max(ttf, maxTtf)}}.

Also I liked it better in the previous patch how you built a new TermContext instance instead of modifying the current one in place. Maybe you could add it back?


was (Author: jpountz):
It's not correct to do {{maxTtf = Math.max(ttf, maxTtf)}} because the ttf can sometimes be -1, so it would rather need to be something like {{maxTtf = ttf == -1 ? -1 : Math.max(ttf, maxTtf)}}.

Also I liked it better in the previous patch how you built a new TermContext instance instead of modifying the current one in place. Maybe you could add it back?

> Fuzzy query scoring issues
> --------------------------
>
>                 Key: LUCENE-329
>                 URL: https://issues.apache.org/jira/browse/LUCENE-329
>             Project: Lucene - Core
>          Issue Type: Bug
>          Components: core/search
>    Affects Versions: 1.2
>         Environment: Operating System: All
> Platform: All
>            Reporter: Mark Harwood
>            Assignee: Mark Harwood
>            Priority: Minor
>             Fix For: 5.x
>
>         Attachments: ASF.LICENSE.NOT.GRANTED--patch.txt, LUCENE-329.patch, LUCENE-329.patch
>
>
> Queries which automatically produce multiple terms (wildcard, range, prefix, 
> fuzzy etc)currently suffer from two problems:
> 1) Scores for matching documents are significantly smaller than term queries 
> because of the volume of terms introduced (A match on query Foo~ is 0.1 
> whereas a match on query Foo is 1).
> 2) The rarer forms of expanded terms are favoured over those of more common 
> forms because of the IDF. When using Fuzzy queries for example, rare mis-
> spellings typically appear in results before the more common correct spellings.
> I will attach a patch that corrects the issues identified above by 
> 1) Overriding Similarity.coord to counteract the downplaying of scores 
> introduced by expanding terms.
> 2) Taking the IDF factor of the most common form of expanded terms as the 
> basis of scoring all other expanded terms.



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