Abstract

We present a semantic framework for the deductive verification of hybrid systems with Isabelle/HOL. It supports reasoning about the temporal evolutions of hybrid programs in the style of differential dynamic logic modelled by flows or invariant sets for vector fields. We introduce the semantic foundations of this framework and summarise their Isabelle formalisation as well as the resulting verification components. A series of simple examples shows our approach at work.

Highlights

  • Hybrid systems combine continuous dynamics with discrete control

  • Before developing relational and state transformer models for the basic evolution commands of hybrid programs we briefly review some basic facts about continuous dynamical systems and ordinary differential equations

  • We have presented a new semantic framework for the deductive verification of hybrid systems with the Isabelle/HOL proof assistant

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Summary

Introduction

Hybrid systems combine continuous dynamics with discrete control. Their verification is receiving increasing attention as the number of computing systems controlling real-world physical systems is growing. Hybrid system verification requires integrating continuous system dynamics, often modelled by systems of differential equations, and discrete control components into hybrid automata, hybrid programs or similar domain-specific modelling formalisms, and into analysis techniques for these. After certifying the flow conditions and checking Lipschitz continuity of the vector field, as dictated by the Picard–Lindelöf theorem, the orbit for the flow can be used to compute the weakest liberal preconditions for the evolution command This workflow deviates from dL in allowing users to supply an interval of interest as domain of the flow. – The third workflow uses flows ab initio in the specification and semantic analysis of evolution commands This circumvents checking any continuity, existence, uniqueness or invariant conditions of vector fields mentioned. A glossary of cross-references between theorems in the text and the Isabelle theories is presented in Appendix A

Kleene Algebra
Modal Kleene Algebra
Predicate Transformers à la Back and von Wright
Predicate Transformers from the Powerset Monad
Assignments
Ordinary Differential Equations
Evolution Commands for Lipschitz Continuous Vector Fields
10 Evolution Commands for Continuous Vector Fields
11 Invariants for Evolution Commands
Check whether a candidate predicate I is a differential invariant:
12 Derivation of dL Inference Rules
13 Isabelle Components for MKA and Predicate Transformers
14 Isabelle Components for ODEs and Orbits
15 Isabelle Components for Hybrid Programs
16 Isabelle Support for dL-Style Reasoning
17 Verification Examples
18 Outlook: A Flow-Based Verification Component
19 Related Work
20 Conclusion
Result in article
Full Text
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