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Posted to dev@lucene.apache.org by "Robert Muir (Updated) (JIRA)" <ji...@apache.org> on 2011/12/21 02:15:30 UTC
[jira] [Updated] (LUCENE-3662) extend LevenshteinAutomata to
support transpositions as primitive edits
[ https://issues.apache.org/jira/browse/LUCENE-3662?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Robert Muir updated LUCENE-3662:
--------------------------------
Attachment: update-moman.patch
as a start, i thought we could try upgrading moman, passing 'False' for transpositions (as if you pass true, it uses the extended state notation including t-positions and this really makes our code-generator angry).
But already there is some silly problem (likely in our code generator). I'll attach some files showing how the difference in the moman output changed
> extend LevenshteinAutomata to support transpositions as primitive edits
> -----------------------------------------------------------------------
>
> Key: LUCENE-3662
> URL: https://issues.apache.org/jira/browse/LUCENE-3662
> Project: Lucene - Java
> Issue Type: New Feature
> Affects Versions: 4.0
> Reporter: Robert Muir
> Attachments: update-moman.patch
>
>
> This would be a nice improvement for spell correction: currently a transposition counts as 2 edits,
> which means users of DirectSpellChecker must use larger values of n (e.g. 2 instead of 1) and
> larger priority queue sizes, plus some sort of re-ranking with another distance measure for good results.
> Instead if we can integrate "chapter 7" of http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.16.652
> then you can just build an alternative DFA where a transposition is only a single edit
> (http://en.wikipedia.org/wiki/Damerau%E2%80%93Levenshtein_distance)
> According to the benchmarks in the original paper, the performance for LevT looks to be very similar to Lev.
> Support for this is now in moman (https://bitbucket.org/jpbarrette/moman/) thanks to Jean-Philippe
> Barrette-LaPierre.
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