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While there may be general agreement on what it means for a formal method to be usable (e.g., ease of modelling, automated and scalable analysis), there is no consensus in the software-engineering or formal-methods communities on what strategies lead to more usable formalisms. In this paper, we aim to raise discussion around such strategies by proposing fourteen concrete recommendations for achieving practical formal methods. Our recommendations apply to research in formal modelling, automated analysis, and automated transformation (e.g., transforming a model into the input to an analysis tool). Our recommendations focus on formal methods for functional requirements of software product lines, as per our experience in this area as part of a research project in collaboration with an automotive manufacturer; however, most of the recommendations apply to formal methods in general. We also provide a brief overview of a formal modelling language and an underdevelopment tool chain that realizes our recommendations.

A self-stabilizing system is one that guarantees reaching a set of legitimate states from any arbitrary initial state. Designing distributed self-stabilizing protocols is often a complex task and developing their proof of correctness is known to be significantly more tedious. In this article, we propose an SMT-based method that automatically synthesizes a self-stabilizing protocol, given the network topology of distributed processes and description of the set of legitimate states. Our method can synthesize synchronous, asynchronous, symmetric, and asymmetric protocols for two types of stabilization, namely weak and strong . We also report on successful automated synthesis of a set of well-known distributed stabilizing protocols such as Dijkstra’s token ring, distributed maximal matching, graph coloring, and mutual exclusion in anonymous networks.

Abstract. In this paper, we introduce an SMT-based method that automatically synthesizes a distributed self-stabilizing protocol from a given high-level specification and network topology. Unlike existing approaches, where synthesis algorithms require the explicit description of the set of legitimate states, our technique only needs the temporal behavior of the protocol. We extend our approach to synthesize ideal-stabilizing protocols, where every state is legitimate. We also extend our technique to synthesize monotonic-stabilizing protocols, where during recovery, each process can execute an most once one action. Our proposed methods are fully implemented and we report successful synthesis of well-known protocols such as Dijkstra's token ring, a self-stabilizing version of Raymond's mutual exclusion algorithm, ideal-stabilizing leader election and local mutual exclusion, as well as monotonic-stabilizing maximal independent set and distributed Grundy coloring.

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