We consider verification of safety properties for concurrent real-timed systems modelled by timed Petri nets, by performing symbolic forward reachability analysis. We introduce a formalism, called region generators for representing sets of markings of timed Petri nets. Region generators characterize downward closed sets of regions. Downward closed languages provide exact abstractions of sets of reachable states with respect to safety properties.
We show that the standard operations needed for performing symbolic reachability analysis are computable for region generators. Since forward reachability analysis is necessarily incomplete, we introduce an acceleration technique to make the procedure terminate more often on practical examples.
We have implemented a prototype for analyzing timed Petri nets and used it to verify a parameterized version of Fischer's protocol. We also used the tool to generate a finite-state abstraction of the protocol.
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