Effective Hybrid System Falsification Using Monte Carlo Tree Search Guided by QB-Robustness

Zhenya Zhang, Deyun Lyu, Paolo Arcaini, Lei Ma, Ichiro Hasuo, Jianjun Zhao

Research output: Chapter in Book/Report/Conference proceedingConference contribution

14 Citations (Scopus)


Hybrid system falsification is an important quality assurance method for cyber-physical systems with the advantage of scalability and feasibility in practice than exhaustive verification. Falsification, given a desired temporal specification, tries to find an input of violation instead of a proof guarantee. The state-of-the-art falsification approaches often employ stochastic hill-climbing optimization that minimizes the degree of satisfaction of the temporal specification, given by its quantitative robust semantics. However, it has been shown that the performance of falsification could be severely affected by the so-called scale problem, related to the different scales of the signals used in the specification (e.g., rpm and speed): in the robustness computation, the contribution of a signal could be masked by another one. In this paper, we propose a novel approach to tackle this problem. We first introduce a new robustness definition, called QB-Robustness, which combines classical Boolean satisfaction and quantitative robustness. We prove that QB-Robustness can be used to judge the satisfaction of the specification and avoid the scale problem in its computation. QB-Robustness is exploited by a falsification approach based on Monte Carlo Tree Search over the structure of the formal specification. First, tree traversal identifies the sub-formulas for which it is needed to compute the quantitative robustness. Then, on the leaves, numerical hill-climbing optimization is performed, aiming to falsify such sub-formulas. Our in-depth evaluation on multiple benchmarks demonstrates that our approach achieves better falsification results than the state-of-the-art falsification approaches guided by the classical quantitative robustness, and it is largely not affected by the scale problem.

Original languageEnglish
Title of host publicationComputer Aided Verification - 33rd International Conference, CAV 2021, Proceedings
EditorsAlexandra Silva, K. Rustan Leino
PublisherSpringer Science and Business Media Deutschland GmbH
Number of pages24
ISBN (Print)9783030816841
Publication statusPublished - 2021
Event33rd International Conference on Computer Aided Verification, CAV 2021 - Virtual, Online
Duration: Jul 20 2021Jul 23 2021

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume12759 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference33rd International Conference on Computer Aided Verification, CAV 2021
CityVirtual, Online

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • General Computer Science


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