Hi Edson, I'd explore Ralf Koster's research. I think he covered this in one of his presentations a few years ago:: http://www.theoryoffun.com/grammar/gdc2005.htm // jeff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Posted from the new ixda.org http://www.ixda.org/discuss?post=27814