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We investigate how the semantics of a hybrid automaton deviates with respect to syntactic perturbations on the hybrid automaton. We consider syntactic perturbations of a hybrid automaton, wherein the syntactic representations of its elements, namely, initial sets, invariants, guards, and flows, in some logic are perturbed. Our main result establishes a continuity like property that states that small perturbations in the syntax lead to small perturbations in the semantics. More precisely, we show that for every real number epsilon>0 and natural number k, there is a real number delta>0 such that H^delta, the delta syntactic perturbation of a hybrid automaton H, is epsilon-simulation equivalent to H up to k transition steps. As a byproduct, we obtain a proof that a bounded safety verification tool such as dReach will eventually prove the safety of a safe hybrid automaton design (when only non-strict inequalities are used in all constraints) if dReach iteratively reduces the syntactic parameter delta that is used in checking approximate satisfiability. This has an immediate application in counter-example validation in a CEGAR framework, namely, when a counter-example is spurious, then we have a complete procedure for deducing the same.
@InProceedings{roohi_et_al:LIPIcs.CONCUR.2018.26,
author = {Roohi, Nima and Prabhakar, Pavithra and Viswanathan, Mahesh},
title = {{Relating Syntactic and Semantic Perturbations of Hybrid Automata}},
booktitle = {29th International Conference on Concurrency Theory (CONCUR 2018)},
pages = {26:1--26:16},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-087-3},
ISSN = {1868-8969},
year = {2018},
volume = {118},
editor = {Schewe, Sven and Zhang, Lijun},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2018.26},
URN = {urn:nbn:de:0030-drops-95644},
doi = {10.4230/LIPIcs.CONCUR.2018.26},
annote = {Keywords: Model Checking, Hybrid Automata, Approximation, Perturbation}
}