This paper describes the nuXmv symbolic model checker for finite- and infinite-state synchronous transition systems. nuXmv is the evolution of the nuXmv open source model checker. It builds on and extends nuXmv along two main directions. For finite-state systems it complements the basic verification techniques of nuXmv with state-of-the-art verification algorithms. For infinite-state systems, it extends the nuXmv language with new data types, namely Integers and Reals, and it provides advanced SMT-based model checking techniques.

Besides extended functionalities, nuXmv has been optimized in terms of performance to be competitive with the state of the art. nuXmv has been used in several industrial projects as verification back-end, and it is the basis for several extensions to cope with requirements analysis, contract based design, model checking of hybrid systems, safety assessment, and software model checking.

/pdf/the-nuxmv-symbolic-model-checker-22a2teb50o.pdf

The nuXmv Symbolic Model Checker

https://chess.eecs.berkeley.edu/design/2012/discussions/Pdf/ASVDammPasserone_CDC_EJC.pdf

Taming Dr. Frankenstein: Contract-Based Design for Cyber-Physical Systems

Recently, contract-based design has been proposed as an “orthogonal” approach that complements system design methodologies proposed so far to cope with the complexity of system design. Contract-based design provides a rigorous scaffolding for verification, analysis, abstraction/refinement, and even synthesis. A number of results have been obtained in this domain but a unified treatment of the topic that can help put contract-based design in perspective was missing. This monograph intends to provide such a treatment where contracts are precisely defined and characterized so that they can be used in design methodologies with no ambiguity. In particular, this monograph identifies the essence of complex system design using contracts through a mathematical “meta-theory”, where all the properties of the methodology are derived from a very abstract and generic notion of contract. We show that the meta-theory provides deep and illuminating links with existing contract and interface theories, as well as guidelines for designing new theories. Our study encompasses contracts for both software and systems, with emphasis on the latter. We illustrate the use of contracts with two examples: requirement engineering for a parking garage management, and the development of contracts for timing and scheduling in the context of the AUTOSAR methodology in use in the automotive sector.

/pdf/contracts-for-system-design-4rnwl90agh.pdf

Contracts for System Design

Traditionally, research on model-driven engineering (MDE) has mainly focused on the use of models at the design, implementation, and verification stages of development. This work has produced relatively mature techniques and tools that are currently being used in industry and academia. However, software models also have the potential to be used at runtime, to monitor and verify particular aspects of runtime behavior, and to implement self-* capabilities (e.g., adaptation technologies used in self-healing, self-managing, self-optimizing systems). A key benefit of using models at runtime is that they can provide a richer semantic base for runtime decision-making related to runtime system concerns associated with autonomic and adaptive systems. This book is one of the outcomes of the Dagstuhl Seminar 11481 on models@run.time held in November/December 2011, discussing foundations, techniques, mechanisms, state of the art, research challenges, and applications for the use of runtime models. The book comprises four research roadmaps, written by the original participants of the Dagstuhl Seminar over the course of two years following the seminar, and seven research papers from experts in the area. The roadmap papers provide insights to key features of the use of runtime models and identify the following research challenges: the need for a reference architecture, uncertainty tackled by runtime models, mechanisms for leveraging runtime models for self-adaptive software, and the use of models at runtime to address assurance for self-adaptive systems.

Models@run.time: foundations, applications, and roadmaps

A survey: Cyber-physical-social systems and their system-level design methodology

We present the mathematical foundations and the design methodology of the contract-based model developed in the framework of the SPEEDS project. SPEEDS aims at developing methods and tools to support "speculative design", a design methodology in which distributed designers develop different aspects of the overall system, in a concurrent but controlled way. Our generic mathematical model of contract supports this style of development. This is achieved by focusing on behaviors, by supporting the notion of "rich component" where diverse (functional and non-functional) aspects of the system can be considered and combined, by representing rich components via their set of associated contracts, and by formalizing the whole process of component composition.

/pdf/multiple-viewpoint-contract-based-specification-and-design-1f0grfsxei.pdf

Multiple Viewpoint Contract-Based Specification and Design

We present the mathematical formalism and the verification methodology of the contract-based model developed in the framework of the SPEEDS project. SPEEDS aims at developing methods and tools to support ldquospeculative designrdquo, a design methodology in which distributed designers develop different aspects of the overall system, in a concurrent but controlled way. Our generic mathematical model of contract supports this style of development. This is achieved by focusing on behaviors, by supporting the notion of ldquorich componentrdquo where functional and non-functional aspects of the system can be considered and combined, by representing rich components via their set of associated contracts, and by formalizing the process of component composition.

/pdf/a-contract-based-formalism-for-the-specification-of-ri5ti6xrqv.pdf

A contract-based formalism for the specification of heterogeneous systems

In this paper we present Parallel NuSMV, a tool based on the NuSMV model checker that integrates the ManySAT parallel SAT solver. The PNuSMV is part of the FormalSpecs Verifier framework for the formal verification of Simulink/Stateflow models. The experiments we performed show that the use of a parallel SAT solver allows for an average speedup of an order of magnitude or more on industry-level size models. The main contributions of the papers are (1) the description of the PNuSMV model checker (2) the description of the verification time speedup w.r.t. the NuSMV tool for the verification of industrial-sized embedded systems and (3) the integration of the tool in the FormalSpecs Verifier framework for the verification of Simulink/Stateflow models with the application to a cruise control case study.

Parallel NuSMV: a NuSMV extension for the verification of complex embedded systems

The design of large scale complex systems demands the ability to correctly specify and verify as early as possible in the design cycle the interaction of the different components that ensure that the global level requirements are satisfied. We address this issue using an approach based on the notion of contract. In particular, we propose a graphical and text-based language for requirement definition that allows designers to incrementally and hierarchically construct contract specifications for system components by composing a set of simple and intuitive patterns. The patterns have a formal semantics, and are implemented as monitor components in the Simulink framework for runtime verification. The contracts are simulated together with the components to verify both satisfaction and compatibility. A cruise control case study demonstrates the effectiveness of the approach.

BCL: A compositional contract language for embedded systems

The design of large scale complex systems demands the ability to correctly specify and verify as early as possible in the design cycle the interaction of the different components to ensure that the global level requirements are satisfied. We address this issue using an approach based on the notion of contract and simulation-based verification. In particular, we extend traditional contract verification methods to target distributed systems, which require an asynchronous communication paradigm. We use a pattern-based language for requirement definition, from which we generate a set of contract monitors implemented in the Simulink framework to observe the underlying system execution and flag violating behaviors. In the paper, we discuss in particular the aspects related to handling the asynchronous interaction between components and their relation to the contract monitors. An automatic towing system case study demonstrates the approach.

https://ieeexplore.ieee.org/iel7/6867218/6871170/07087332.pdf

Christos Sofronis

Papers

Multiple Viewpoint Contract-Based Specification and Design

A contract-based formalism for the specification of heterogeneous systems

Parallel NuSMV: a NuSMV extension for the verification of complex embedded systems

BCL: A compositional contract language for embedded systems

Monitor-based run-time contract verification of distributed systems