Roy Armoni Limor Fix Alon Flaisher Orna Grumberg Nir Piterman Andreas Tiemeyer Moshe Y. Vardi Enhanced Vacuity Detection in Linear Temporal Logic. 368-380 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2725&spage=368 2003 conf/cav/2003 CAV db/conf/cav/cav2003.html#ArmoniFFGPTV03