We introduce the novel notion of quasi-equal clocks and use it to improve the verification time of networks of timed automata. Intuitively, two clocks are quasi-equal if, during each run of the system, they have the same valuation except for those points in time where they are reset. We propose a transformation that takes a network of timed automata and yields a network of timed automata which has a smaller set of clocks and preserves properties up to those not comparing quasi-equal clocks. Our experiments demonstrate that the verification time in three transformed real world examples is much lower compared to the original.
The concept of hybrid automata provides a powerful framework to model and analyze real-world systems. Due to the structural complexity of hybrid systems it is important to ensure the scalability of analysis algorithms. We approach this problem by providing an effective generalisation of the recently introduced notion of quasi-equal clocks to hybrid systems. For this purpose, we introduce the concept of quasi-dependent variables. Our contribution is two-fold: we demonstrate how such variables can be automatically detected, and we present a transformation leading to an abstraction with a smaller state space which, however, still retains the same properties as the original system. We demonstrate the practical applicability of our methods on a range of industrial benchmarks.
In this paper, we propose a benchmark for verification of properties of fault-tolerant clock synchronization algorithms, namely, a benchmark of a TTEthernet network, where properties of the clock synchronization algorithm as implemented in a TTEthernet network can be verified, and optimization techniques for verification purposes can be applied. Our benchmark, which assumes non-faulty components, aims to be a basis for verifying configurations which include faulty components, information consistency mechanisms, and for verifying other clock synchronization algorithms.
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