Parosh Aziz Abdulla Pritha Mahata Richard Mayr Decidability of Zenoness, Syntactic Boundedness and Token-Liveness for Dense-Timed Petri Nets. 58-70 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3328&spage=58 2004 conf/fsttcs/2004 FSTTCS db/conf/fsttcs/fsttcs2004.html#AbdullaMM04