Abstract

We present an approach for verifying Statecharts including infinite data spaces. We devise a technique for checking that a formula of the universal fragment of CTL is satisfied by a specification written as a Statechart. The approach is based on a property-preserving abstraction technique that additionally preserves structure. It is prototypically implemented in a logic-based framework using a theorem prover and a model checker. This paper reports on the following results. (1) We present a proof infra-structure for Statecharts in the theorem prover Isabelle/HOL, which constitutes a basis for defining a mechanised data abstraction process. The formalisation is based on Hierar-chical Automata (HA) which allow a structural decomposition of Statecharts into Sequential Automata. (2) Based on this theory we introduce a data abstraction technique, which can be used to abstract the data space of a HA for a given abstraction function. The technique is based on constructing over-approximations. It is structure-preserving and is designed in a compositional way. (3) For reasons of practicability, we finally present two tactics supporting the abstraction that we have implemented in Isabelle/HOL. To make proofs more efficient, these tactics use the model checker SMV checking abstract models automatically.

Highlights

  • The Statecharts formalism [1] combines a state based automata formalism with intuitive behaviour and hierarchical and parallel state composition

  • (1) We present a proof infra-structure for Statecharts in the theorem prover Isabelle/HOL, which constitutes a basis for defining a mechanised data abstraction process

  • The formalisation is based on Hierarchical Automata (HA) which allow a structural decomposition of Statecharts into Sequential Automata

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Summary

INTRODUCTION

The Statecharts formalism [1] combines a state based automata formalism with intuitive behaviour and hierarchical and parallel state composition. In 2000, for example, Issa Traore presented a formalisation for UML Statecharts that was expressed in the input language of PVS [16] He documents in his work how UML Statecharts can be verified using a model checker available in PVS. The main difference to our work is that they abstract and refine the interfaces of the state machines only, which does not work for Statemate-Statecharts Further they use a “don’t-know” value for data variables, which changes the semantics of UML state machines slightly. He proposes in his work a semantics for Statecharts based on Extended HA [5] and uses this as a basis for model checking He defines and implements one translation to the input language of the www.ijacsa.thesai.org.

Relation to our Previous Work
Example Specification
Optimisation
DATA ABSTRACTION
Property Preserving Abstraction
Overapproximation of SA
Semantical Characteristics of HAs
MODEL CHECKING STATECHARTS
Findings
CONCLUSIONS
Full Text
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