[Mediawiki-l] Enabling boolean search (AND, NOT, OR)

[amoe]

hello

I noticed that in the English version of wikipedia it is possible to do 
boolean searches, but in the German one it is disabled, as it is in the 
mediaWiki I just installed for myself. I did some research about this, 
but everyone seems to be telling something different than the other guy.

Do you know how to enable boolean searches in mediaWiki? (maybe using 
the AND, NOT, OR syntax or the one with the plus, minus and tilde signs 
from mySQL)?

thank you

Stef