Ishii-san,
Ok, probably we need to copy the English stemming rule to the one for Japanese.Pardon my ignorance here, but is the concept of stemming even relevant to Japanese/Chinese/Korean? What little I know about ideographic languages suggests it wouldn't work well. And surely the specific rules in the Snowball project's English stemmer wouldn't work.Your undestanding is correct. English stemmer would not work for Japanese "non English" part.
That reminds me, don't you guys have your own full text search for Japanese? Planning on merging it with the core code anytime soon?
--Josh