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https://issues.apache.org/jira/browse/LUCENE-329?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833822#action_12833822
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Mark Harwood commented on LUCENE-329:
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The problem with ignoring IDF completely is that it doesn't help balance
partial matches where there is >1 fuzzy element in the query e.g.in a query
for John~ Patitucci~ I'm probably more interested in a partial match on the
rarer surname than a partial match on the common forename. Obliterating IDF
completely as a factor would lose this feature (available in FuzzyLikeThisQuery)
> Fuzzy query scoring issues
> --------------------------
>
> Key: LUCENE-329
> URL: https://issues.apache.org/jira/browse/LUCENE-329
> Project: Lucene - Java
> Issue Type: Bug
> Components: Search
> Affects Versions: 1.2rc5
> Environment: Operating System: All
> Platform: All
> Reporter: Mark Harwood
> Assignee: Lucene Developers
> Priority: Minor
> Attachments: patch.txt
>
>
> 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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