Abstract We present a tool for using the B language in computational notebooks, based on the Jupyter Notebook interface and the ProB tool. Applications of B notebooks include executable documentation of formal models, interactive manuals, validation reports but also teaching of formal methods, logic, set theory and theoretical computer science. In addition to B and Event-B, the tool supports Z, (\textsc {TLA}^{+}) and Alloy.
Abstract The CLEARSY Safety Platform (CSSP) is aimed at easing the development and the deployment of safety critical applications, up to the safety integrity level 4 (SIL4). It relies on the smart integration of the B formal method, redundant code generation and compilation, and a hardware platform that ensures a safe execution of the software. This paper exposes the programming model of the CSSP used to develop control & command applications based on digital I/Os.
Abstract Statechart notations with ‘run to completion’ semantics, are popular with engineers for designing controllers that respond to events in the environment with a sequence of state transitions. However, they lack formal refinement and rigorous verification methods. , on the other hand, is based on refinement from an initial abstraction and is designed to make formal verification by automatic theorem provers feasible. We introduce a notion of refinement into a ‘run to completion’ statechart modelling notation, and leverage tool support for theorem proving. We describe the difficulties in translating ‘run to completion’ semantics into refinements and suggest a solution. We outline how safety and liveness properties could be verified.
Abstract Abstract State Machine (ASM) theory is a well-known state-based formal method to analyze, verify, and specify software and hardware systems. Nowadays, as in other state-based formal methods, the proposed specification languages for ASMs still lack easy-to-comprehend language constructs for type abstractions to describe reusable and maintainable specifications. Almost all built-in behaviors are implicitly defined inside a concrete ASM language implementation and thus, the behavior is hidden from the language user. In this paper, we present a new ASM syntax extension based on traits, which allows the specifier (language user) to define new type abstractions in the form of structure and behavior definitions to reuse, maintain, structure, and extend the functionality in ASM specifications. We describe the proposed language construct by defining its syntax and semantics. The decision to use a trait-based syntax extension over other object-oriented language constructs like interfaces or mixins was motivated and driven by the results of previously conducted empirical studies. Moreover, we outline details about the implementation of the trait-based syntax extension in our Corinthian Abstract State Machine (CASM) language implementation.
Abstract Many formal methods research communities lack a shared set of benchmarks. As a result, many research articles in the past have evaluated new techniques on specifications that are specifically tailored to the problem or not publicly available. While this is great for proving the concept in question, it does not offer any insights on how it performs on real-world examples. Additionally, with machine learning techniques gaining more popularity, a larger set of public specifications is required. In this paper, we present our public set of B machines and urge contribution. As we think this to be an issue in other communities in scope of the ABZ as well, we are also interested in specifications expressed in other formalisms, for example Alloy, TLA(^{+}) or Z.
Abstract This paper describes the formalisation of SGAC access control policies using Z3 and then we compare the performance with ProB and Alloy. SGAC is an attribute-based, fine-grain access control model that uses acyclic subject and resource graphs to provide rule inheritance and streamline policy specification. To ensure patient privacy and safety, four types of properties are checked: accessibility, availability, contextuality and rule effectiveness. Automatic translation of SGAC policies into each specification language has been defined. ProB offers the best verification performances, by two orders of magnitude. The performances of Alloy and Z3 are similar.
Abstract Visualization is important to present formal models to domain experts and to spot issues which are hard to formalise or have not been formalised yet. VisB is a visualization plugin for the ProB animator and model checker. VisB enables the user to create simple visualizations for formal models. An important design criterion was to re-use scalable vector graphics (SVG) generated by off-the-shelf graphic editors using a lightweight and easy-to-use annotation mechanism. The visualizations can be used to formal models in B, Event-B, Z, TLA+ and Alloy.
This document describes two systems from the automotive domain: an adaptive exterior light system (ELS) and a speed control system (SCS). This specification is based on the SPES XT running example. Besides their general architectures, the requirements of the software based controllers are described. Both systems are only loosely coupled, which makes it possible to handle them independently