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From "Jonathan O'Connor" <>
Subject Re: Questions about GermanAnalyzer/Stemmer [auf Viren geprueft]
Date Tue, 01 Mar 2005 11:18:55 GMT
I too found some problems with the German analyser recently. Here's what 
may help:
1. You can try reading Joerg Caumanns' paper "A Fast and Simple Stemming 
Algorithm for German Words". This paper describes the algorithm 
implemented by GermanAnalyser.
2. I guess German nouns all capitalized, so maybe that's why. Although you 
would want to be indexing well written German and not emails or text 
3. The German Stemmer converts umlauts into some funny form (the code is a 
bit tricky, and I didn't spend any time looking at it), so maybe thats why 
you can't find umlauts properly. I think the main reason for this umlaut 
change is that many plurals are formed by umlauting: E.g. Haus, Haeuser 
(that ae is a umlaut).

Finally, to really understand what's happening, get your hands on Luke. I 
just got it last week, and its brilliant. It shows you everything about 
your indexes. You can also feed text to an Analyser, and see what it makes 
of it. This will show you the real reason why your umlaut search is 
Jonathan O'Connor
XCOM Dublin

"Jon Humble" <> 
01/03/2005 09:35
Please respond to
"Lucene Users List" <>


Questions about GermanAnalyzer/Stemmer [auf Viren geprueft]

We?re using the GermanAnalyzer/Stemmer to index/search our (German)
I have a few questions:
(1)     Why is the GermanAnalyzer case-sensitive? None of the other
language indexers seem to be. What does this feature add?
(2)     With the German Analyzer, wildcard searches containing extended
German characters do not seem to work. So, a* is fine but anä* or ö*
always find zero results. 
(3)     In a similar vein to (2), wildcard searches with escaped special
characters fail to find results. So a search for co\-operative works but
a search for co\-op* fails.
I will be grateful for any light that can be shed on these problems.
With Thanks,
Jon Humble
BSc (hons,)
Software Engineer

TecSphere Ltd
Centre for Advanced Industry
Coble Dene, Royal Quays
Newcastle upon Tyne NE29 6DE
United Kingdom
Direct Dial: +44 (191) 270 31 06
Fax: +44 (191) 270 31 09

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