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https://issues.apache.org/jira/browse/LUCENE-8025?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16226180#comment-16226180
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Robert Muir commented on LUCENE-8025:
-------------------------------------
I added DFI and LM as well, they are the worst case: just fall apart completely
today for omitTFAP because the bogus sumTotalTF=docFreq makes them lose the
ability to discriminate term importance too.
> compute avgdl correctly for DOCS_ONLY
> -------------------------------------
>
> Key: LUCENE-8025
> URL: https://issues.apache.org/jira/browse/LUCENE-8025
> Project: Lucene - Core
> Issue Type: Bug
> Reporter: Robert Muir
> Attachments: LUCENE-8025.patch
>
>
> Spinoff of LUCENE-8007:
> If you omit term frequencies, we should score as if all tf values were 1.
> This is the way it worked for e.g. ClassicSimilarity and you can understand
> how it degrades.
> However for sims such as BM25, we bail out on computing avg doclength (and
> just return a bogus value of 1) today, screwing up stuff related to length
> normalization too, which is separate.
> Instead of a bogus value, we should substitute sumDocFreq for
> sumTotalTermFreq (all postings have freq of 1, since you omitted them).
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