On Mar 12, 2008, at 3:10 , Romain Gros wrote: > http://www.globalgallery.com/prod_images/esc-e6.jpg > > or > > http://www.claymath.org/gallery/escher.jpg Heh, I saw these in real life this weekend at the Escher museum :) -- Joost Schuttelaar The Hague, NL