Antonio di Nola Ada Lettieri Formulas of Lukasiewicz's Logic Represented by Hyperplanes. 189-194 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2715&spage=189 2003 conf/ifsa/2003 IFSA db/conf/ifsa/ifsa2003.html#NolaL03