Ferruccio Damiani Rank 2 Intersection for Recursive Definitions. 451-488 2007 77 Fundam. Inform. 4 http://iospress.metapress.com/openurl.asp?genre=article&issn=0169-2968&volume=77&issue=4&spage=451 db/journals/fuin/fuin77.html#Damiani07