[Perl-AI] AI::Categorizer and Umlauts?

Hi,

I seem to have problems with umlauts, such as in words

Präsentation

When a document is added with

return new AI::Categorizer::Document(name => $filename,
content => $content);

to the collection, after loading and finish, the feature vector
contains only fragments of these words, such as

pr => 1
sentation => 1

Setting the locale on the shell or in Perl does not have any effect

use locale;

not even with turning on de_AT explicitly.