Time-Darts: A Data Structure for Verification of Closed Timed Automata

Kenneth Y. Jørgensen; Kim G. Larsen; Jiří Srba

doi:10.4204/eptcs.102.13

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arXiv · 1211.6195

Time-Darts: A Data Structure for Verification of Closed Timed Automata

Kenneth Y. Jørgensen·Kim G. Larsen·Jiří Srba

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Abstract

Symbolic data structures for model checking timed systems have been subject to a significant research, with Difference Bound Matrices (DBMs) still being the preferred data structure in several mature verification tools. In comparison, discretization offers an easy alternative, with all operations having linear-time complexity in the number of clocks, and yet valid for a large class of closed systems. Unfortunately, fine-grained discretization causes itself a state-space explosion. We introduce a new data structure called time-darts for the symbolic representation of state-spaces of timed automata. Compared with the complete discretization, a single time-dart allows to represent an arbitrary large set of states, yet the time complexity of operations on time-darts remain linear in the number of clocks. We prove the correctness of the suggested reachability algorithm and perform several experiments in order to compare the performance of time-darts and the complete discretization. The main conclusion is that in all our experiments the time-dart method outperforms the complete discretization and it scales significantly better for models with larger constants.

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Kenneth Y. Jørgensen, Kim G. Larsen, Jiří Srba. 2012-11-27. Time-Darts: A Data Structure for Verification of Closed Timed Automata. https://doi.org/10.4204/eptcs.102.13

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