Masahiko Kawabe Robert Glück The Program Inverter LRinv and Its Structure. 219-234 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3350&spage=219 2005 conf/padl/2005 PADL db/conf/padl/padl2005.html#KawabeG05