Bernard Berthomieu Didier Lime Olivier H. Roux François Vernadat Reachability Problems and Abstract State Spaces for Time Petri Nets with Stopwatches. 133-158 2007 17 Discrete Event Dynamic Systems 2 http://dx.doi.org/10.1007/s10626-006-0011-y db/journals/deds/deds17.html#BerthomieuLRV07