An experimental tool for checking probabilistic program refinement

We discuss the features and current status of a software tool developed for checking refinement properties of a particular (though still quite general) class of probabilistic nondeterministic programs. The tool has been used successfully for several interesting examples, and its development is currently being expanded to encompass even more classes of probabilistic programs. The novelty of the tool lies in its expressing the refinement checking as a linear satisfiability problem, and also in producing evidence of lack of refinement by a problem of the same kind.Eje: Workshop Ingeniería de software (WIS)Red de Universidades con Carreras en Informátic

A PVS-Simulink Integrated Environment for Model-Based Analysis of Cyber-Physical Systems

This paper presents a methodology, with supporting tool, for formal modeling and analysis of software components in cyber-physical systems. Using our approach, developers can integrate a simulation of logic-based specifications of software components and Simulink models of continuous processes. The integrated simulation is useful to validate the characteristics of discrete system components early in the development process. The same logic-based specifications can also be formally verified using the Prototype Verification System (PVS), to gain additional confidence that the software design complies with specific safety requirements. Modeling patterns are defined for generating the logic-based specifications from the more familiar automata-based formalism. The ultimate aim of this work is to facilitate the introduction of formal verification technologies in the software development process of cyber-physical systems, which typically requires the integrated use of different formalisms and tools. A case study from the medical domain is used to illustrate the approach. A PVS model of a pacemaker is interfaced with a Simulink model of the human heart. The overall cyber-physical system is co-simulated to validate design requirements through exploration of relevant test scenarios. Formal verification with the PVS theorem prover is demonstrated for the pacemaker model for specific safety aspects of the pacemaker design