Joseph A. Goguen Ryoko Amadee Goguen Zero, Connected, Empty: An Essay after a Cantata. 127-128 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2755&spage=127 2002 conf/wadt/2002 WADT db/conf/wadt/wadt2002.html#GoguenG02a