Parosh Aziz Abdulla Johann Deneux Pritha Mahata Closed, Open, and Robust Timed Networks. 117-151 2005 138 Electr. Notes Theor. Comput. Sci. 3 http://dx.doi.org/10.1016/j.entcs.2005.03.027 db/journals/entcs/entcs138.html#AbdullaDM05