Application Of Formal Methods Research Articles

Formal Methods for Industrial Critical Systems

To stimulate the development and application of formal methods in industry, we need to promote research and development for the improvement of formal methods and tools for industrial applications, and we need to exchange experiences of the industrial usage of these methods and tools. This special issue of Software Tools for Technology Transfer presents various tools and experience reports that are targeting the use of formal methods in industry. The papers in this special issue are extended versions of selected conference papers from the proceedings of the 27th International Conference on Formal Methods for Industrial Critical Systems (FMICS 2022).

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Introduction. As an element of legal regulation, private legal regime is a legal category, the concept of which is regarded ambiguously in doctrine and depends on the general understanding of the category «legal regime». Socio-economic, political changes in society are accompanied by changes in the nature of social relations, requiring proper legal regulation in the area of private interest protection.
 Methods. On the basis of the analysis of definitions of legal regime formulated in the theory of law, a generalised approach to the understanding of private legal regime was developed. The application of formal legal method made it possible to reveal the concept and specific features of the private legal regime. The system-structural method was used to determine the significance of legal means (ways, methods, principles, types of legal regulation) in the structure of private legal regime. The application of modelling enabled to reveal the effectiveness of private legal regulation of public relations.
 Results. The concept and essential features of private legal regime are identified; the model of private legal regime as a variable combination of a complex of legal means determining the orientation of private legal regulation of property and personal non-property relations based on equality, autonomy of will and material independence of their participants is defined.

Formal model of multi-agent architecture of a software system based on knowledge interpretation

The use of agents across diverse domains within computer science and artificial intelligence is experiencing a notable surge in response to the imperatives of adaptability, efficiency, and scalability. The subject of this study is the application of formal methods to furnish a framework for knowledge interpretation with a specific focus on the agent-based paradigm in software engineering. This study aims to advance a formal approach to knowledge interpretation by leveraging the agent-based paradigm. The objectives are as follows: 1) to examine the current state of the agent-based paradigm in software engineering; 2) to describe the basic concepts of the knowledge interpretation approach; 3) to study the general structure of the rule extraction task; 4) to develop the reference structure of knowledge interpretation; 5) to develop a multi-agent system architecture; 6) and to discuss the research results. This study employs formal methods, including the use of closed path rules and predicate logic. Specifically, the integration of closed path rules contributes to the extraction and explication of facts from extensive knowledge bases. The obtained results encompass the following: 1) a rule mining approach grounded in closed path rules and tailored for processing extensive datasets; 2) a formalization of relevance that facilitates the scrutiny and automated exclusion of irrelevant fragments from the explanatory framework; and 3) the realization of a multi-agent system predicated on the synergy among five distinct types of agents, dedicated to rule extraction and the interpretation of acquired knowledge. This paper provides an example of the application of the proposed formal tenets, demonstrating their practical context. The conclusion underscores that the agent-based paradigm, with its emphasis on decentralized and autonomous entities, presents an innovative framework for handling the intricacies of knowledge processing. It extends to the retrieval of facts and rules. By distributing functions across multiple agents, the framework offers a dynamic and scalable solution to effectively interpret vast knowledge repositories. This approach is particularly valuable in scenarios where traditional methods may struggle to cope with the volume and complexity of information.

A Case in Point: Verification and Testing of a EULYNX Interface

We present a case study on the application of formal methods in the railway domain. The case study is part of the FormaSig project, which aims to support the development of EULYNX — a European standard defining generic interfaces for railway equipment — using formal methods. We translate the semi-formal SysML models created within EULYNX to formal mCRL2 models. By adopting a model-centric approach in which a formal model is used both for analyzing the quality of the EULYNX specification and for automated compliance testing, a high degree of traceability is achieved. The target of our case study is the EULYNX Point subsystem interface. We present a detailed catalog of the safety requirements, and provide counterexamples that show that some of them do not hold without specific fairness assumptions. We also use the mCRL2 model to generate both random and guided tests, which we apply to a third-party software simulator. We share metrics on the coverage and execution time of the tests, which show that guided testing outperforms random testing. The test results indicate several discrepancies between the model and the simulator. One of these discrepancies is caused by a fault in the simulator, the others are caused by false positives, i.e. an over-approximation of fail verdicts by our test setup.

Understanding technology acceptance in smart agriculture: A systematic review of empirical research in crop production

Smart agriculture offers the potential to analyse agricultural data at a scale not previously possible. Researchers argue that the combination of rich data and intelligent decision support has the potential to improve productivity and profitability in agriculture, whilst also improving sustainability. We argue that achieving this potential requires not just on technological advancement, it also requires a detailed understanding of factors that impact technology acceptance in smart agriculture. Acceptance is necessary if technical advances are to translate into real-world impact. However, technology acceptance is complex and often poorly understood. This systematic review focuses on technology acceptance in prediction and decision support systems in crop production. Major databases were searched to identify papers that formally address technology acceptance and include detailed data. 16 papers met the inclusion criteria and were included in the final analysis. Common facilitators and barriers are identified, and papers are mapping against the Theoretical Framework of Acceptability. This analysis showed that constructs including perceived effectiveness are addressed frequently, but others such as opportunity costs and burden have received less attention. The findings suggest the necessity for greater application of formal methods and the need for standardized, domain-specific methods to support this assessment.

Smart technologies of the risk-management and decision-making systems in a fuzzy data environment

The purpose of this article is to provide a methodology for calculating and predicting the quality of solution implementation in complicated multi-parametric organizational and technological challenges with control agent uncertainty. The article's study findings are centered on the practical application of formal methods in predicting the outcomes of control and decision-making risks under the uncertainty of model agents. The proposed mathematics and simulation applications use a multi-agent strategy to handle the general problem of assessing quality control based on "producer risk (project customer)" and "user risk." Computer experiments with simultaneous graphical visualization of the results improve the accuracy of mathematical modeling, increasing the study's effectiveness. Under the uncertainty of system agents, a simulation model has been designed to analyze and anticipate the dependability of control and the hazards of decision-making. The suggested model is unique in that it takes into account the statistical nature of normative values as well as the rules of equal probability. To handle a frequent problem, the proposed system technique employs a dual approach. It accomplishes this by assessing the quality of the control process based on the magnitude of the risks in the decision-making system.

Formal Methods in Railways: A Systematic Mapping Study

Formal methods are mathematically based techniques for the rigorous development of software-intensive systems. The railway signaling domain is a field in which formal methods have traditionally been applied, with several success stories. This article reports on a mapping study that surveys the landscape of research on applications of formal methods to the development of railway systems. Following the guidelines of systematic reviews, we identify 328 relevant primary studies, and extract information about their demographics, the characteristics of formal methods used and railway-specific aspects. Our main results are as follows: (i) we identify a total of 328 primary studies relevant to our scope published between 1989 and 2020, of which 44% published during the last 5 years and 24% involved industry; (ii) the majority of studies are evaluated through Examples (41%) and Experience Reports (38%), while full-fledged Case Studies are limited (1.5%); (iii) Model checking is the most commonly adopted technique (47%), followed by simulation (27%) and theorem proving (19.5%); (iv) the dominant languages are UML (18%) and B (15%), while frequently used tools are ProB (9%), NuSMV (8%), and UPPAAL (7%); however, a diverse landscape of languages and tools is employed; (v) the majority of systems are interlocking products (40%), followed by models of high-level control logic (27%); and (vi) most of the studies focus on the Architecture (66%) and Detailed Design (45%) development phases. Based on these findings, we highlight current research gaps and expected actions. In particular, the need to focus on more empirically sound research methods, such as Case Studies and Controlled Experiments, and to lower the degree of abstraction, by applying formal methods and tools to development phases that are closer to software development. Our study contributes with an empirically based perspective on the future of research and practice in formal methods applications for railways. It can be used by formal methods researchers to better focus their scientific inquiries, and by railway practitioners for an improved understanding of the interplay between formal methods and their specific application domain.

Distillation of RL Policies with Formal Guarantees via Variational Abstraction of Markov Decision Processes

We consider the challenge of policy simplification and verification in the context of policies learned through reinforcement learning (RL) in continuous environments. In well-behaved settings, RL algorithms have convergence guarantees in the limit. While these guarantees are valuable, they are insufficient for safety-critical applications. Furthermore, they are lost when applying advanced techniques such as deep-RL. To recover guarantees when applying advanced RL algorithms to more complex environments with (i) reachability, (ii) safety-constrained reachability, or (iii) discounted-reward objectives, we build upon the DeepMDP framework to derive new bisimulation bounds between the unknown environment and a learned discrete latent model of it. Our bisimulation bounds enable the application of formal methods for Markov decision processes. Finally, we show how one can use a policy obtained via state-of-the-art RL to efficiently train a variational autoencoder that yields a discrete latent model with provably approximately correct bisimulation guarantees. Additionally, we obtain a distilled version of the policy for the latent model.

Proving the correctness of the algorithm for building a crystallographic space group

An application of formal verification (using the proof assistant Isabelle/HOL) for ensuring the correctness of scientific data processing software in the crystallographic domain is presented. The proposed process consists of writing a pseudocode that describes an algorithm in a succinct but mathematically unambiguous way, then formulating or reusing necessary Isabelle theories and proving algorithm properties within these theories, and finally implementing the algorithm in a practical programming language. Both the formal proof and the semi-formal algorithm analysis are demonstrated on an example of a simple but important algorithm (widely used in crystallographic computing) that reconstructs a space-group operator list from a subset of symmetry operators. The cod-tools software package that implements the verified algorithm is also presented. On the basis of the reported results, it is argued that broader application of formal methods (e.g. formal verification of algorithm correctness) allows developers to improve the reliability of scientific software. Moreover, the formalized (within the proof assistant) domain-specific theory can be reused and gradually extended, thus continuously increasing the automation level of formal algorithm verification.

Exploring the ERTMS/ETCS full moving block specification: an experience with formal methods

Shift2Rail is a joint undertaking funded by the EU via its Horizon 2020 program and by main railway stakeholders. Several Shift2Rail projects aim to investigate the application of formal methods to new ERTMS/ETCS railway signalling systems that promise to move European railway forward by guaranteeing high capacity, low cost and improved reliability. We explore the ERTMS/ETCS level 3 full moving block specifications stemming from different Shift2Rail projects using Uppaal and statistical model checking. The results range from novel rigorously formalised requirements to an operational model formally verified against scenarios with multiple trains on a single railway line. From the gained experience, we have distilled future research goals to improve the formal specification and verification of real-time systems, and we discuss some barriers concerning a possible uptake of formal methods and tools in the railway industry.

Formalism-Driven Development: Concepts, Taxonomy, and Practice

Formal methods are crucial in program specification and verification. Instead of building cases to test functionalities, formal methods specify functionalities as properties and mathematically prove them. Nevertheless, the applicability of formal methods is limited in most development processes due to the requirement of mathematical knowledge for developers. To promote the application of formal methods, we formulate formalism-driven development (FDD), which is an iterative and incremental development process that guides developers to adopt proper formal methods throughout the whole development lifespan. In FDD, system graphs, a variant of transition systems optimized for usability, are designed to model system structures and behaviors with representative properties. System graphs are built iteratively and incrementally via refinement. Properties of system graphs are specified in propositional and temporal logics and verified by model-checking techniques with interpretation over transition system. In addition, skeleton programs are generated based on system graphs and expose implementable interfaces for executing external algorithms and emitting observable effects. Furthermore, we present Seniz, a framework that practicalizes and automates FDD. In this paper, we explicate the concepts and taxonomy of FDD and discuss its practice.

Empirical inquiry without hypotheses: A question‐driven, phenomenon‐based approach to strategic management research

AbstractResearch SummaryMany advances in strategic management have resulted from the application of formal deductive methods, based on tests of specific hypotheses derived from theory. Nonetheless, numerous important research topics involve phenomena that are novel and/or causally complex and so resist basic hypothetico‐deductive logic. As a result, many of the most important findings in strategy research have come from open‐ended studies of relevant phenomena. The special issue of the SMJ on “Question‐Driven and Phenomenon‐Based Empirical Strategy Research” presents innovative ideas for question‐driven research and expands the toolkit of research approaches. In this introduction we describe the twelve articles in the special issue, focusing on how they contribute to continued development of the question‐driven approach to research in strategic management.Managerial SummaryOne of the frustrations managers have with academic research is that it tends to be driven by questions that are theoretically interesting or lend themselves to clever econometrics. Accordingly, the results can lack managerial relevance. We highlight research that takes the opposite approach—identifying important business phenomena and devising empirical approaches to characterize them and derive managerial implications. In this introductory article, we briefly summarize the studies in the special issue, showing how they answer a diverse set of questions using a range of methods.

Lessons learned in the application of formal methods to the design of a storm surge barrier control system∗

The Maeslantkering is a key flood defense infrastructural system in the Netherlands. This movable barrier protects the city and harbor of Rotterdam, without impacting ship traffic under normal circumstances. Its control system, which operates completely autonomously, must be guaranteed to work correctly even under extreme weather conditions, although it closes only sporadically. During its development in the 1990’s, the formal methods Z and Spin were used to increase reliability. As the availability of industrial expert knowledge on these formal methods declines, maintaining the specifications defined back then has become cumbersome. In the quest for an alternative mathematically rigorous approach, this paper reports on an experience in applying supervisory control synthesis. This formal method was recently applied successfully to other types of infrastructural systems like waterway locks, bridges, and tunnels, with the purpose to ensure safe behavior by coordinating hardware components. Here, we show that it can also be used to coordinate several (controller) software systems. Additionally, we compare the lessons learned from the originally used formal methods and link Z to supervisory control synthesis.

Introduction of Formal Methods in Blockchain Consensus Mechanism and Its Associated Protocols

As the size of data is increasing exponentially, its security is a major concern, emerging technology like blockchain is used to provide security. Since the inception of blockchain, it has been adopted by researchers and industry, however, it gained enormous attention after cryptocurrency. It can be defined as a means of storing information in such a way that modification and hacking the system is difficult or impossible. A blockchain is a decentralized ledger that is digital and public, consisting of records of transactions called blocks. A consensus technology assures that all nodes agree on a unique sequence for appending blocks. A comprehensive examination of these algorithms will aid in understanding how and why each blockchain operates in the manner that it does. In this study, we addressed extensively used consensus techniques in the blockchain and the importance of consensus protocol in blockchain technology. The underlying consensus algorithm is a critical component of every blockchain system which determine the performance and security of the system. Ensuring the correctness of consensus protocols is uttermost important to create trust in the blockchain-based systems and formal methods are the way to create that trust and develop correct and verified systems. Formal modeling is a method of writing a system mathematically and examining the correctness and verifying the developed system. This study analyzed the importance of consensus mechanisms and how formal methods are helping to develop a correct blockchain-based system. This paper is a rigorous study on the current scenario of the application of formal methods in the consensus mechanism of blockchain for their verification.

Set-Based Models for Cryptocurrency Software

Formal methods (FM) are mathematics-based software development methods aimed at producing ``code for a nuclear power reactor''. That is, due application of FM can produce bug-free, zero-defect, correct-by-construction, guaranteed, certified software. However, the software industry seldom use FM. One of the main reasons for such a situation is that there exists the perception (which might well be a fact) that FM increase software costs. On the other hand, FM can be partially applied thus producing high-quality software, although not necessarily bug-free.
 In this paper we outline some FM related techniques whose application the cryptocurrency community should take into consideration because they could bridge the gap between ``loose web code'' and ``code for a nuclear power reactor''. We include relevant case studies in the area of cryptocurrency.

Toward a Formal Traceability Model for Efficient Security Validation

A formal traceability model is presented with a real-world application of a gray-box penetration test. Such formal traceability improves test effectiveness and efficiency, thus underlining the applicability and value of formal methods in an industry context.

Automatic Generation of Route Control Chart From Validated Signal Interlocking Plan

Railway signalling is a complex and safety critical problem that has been extensively studied and standardised over a long period of time. The signalling equipment is typically procured from standard vendors and configured with yard specific application logic for which the route control chart (RCC) is a key input. As the yard size increases, the number of routes also increases and accordingly the difficulty of RCC preparation increases rapidly. RCC preparation for big yards may take months and affects the project deadlines adversely. In this work we report computational procedures to address: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$a$ </tex-math></inline-formula> ) capturing of signal interlocking plan (SIP) given on paper and storing it using suitable data structures, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$b$ </tex-math></inline-formula> ) generating the RCC automatically from the captured SIP supported by procedures based on graph theoretic formulation, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$c$ </tex-math></inline-formula> ) storing the SIP graphically in memory, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula> ) application of formal methods towards validation of yard structure and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$e$ </tex-math></inline-formula> ) generation of temporal logic properties for formal verification of electronic interlocking (EI) logic. Several important steps towards RCC generation, such as conflict identification and isolation determination and also validation and verification (V&V) covering yard layout and safety property generation based on graph theoretic modelling are the most interesting aspect of this work. The described techniques have been tested successfully on many actual yards.

On quality assessment of electronic training course interfaces

The development of e-learning, both in distance and mixed forms, becomes especially relevant in the modern educational process. A high-quality e-learning course is developed through the efforts of two parties: the teacher, who creates the methodological content, and the programmer, who creates the electronic shell of the course. The article substantiates the importance of quality issues in the development of a user interface for electronic educational resources, since the user of an electronic course deals with the direct implementation of educational material. The indicators for assessing the quality of software products in accordance with international and Russian standards and their applicability for assessing user interfaces of electronic educational resources are analyzed. The conclusion is made about the importance of the indicator “practicality” in relation to this type of software product as an indicator of an individual evaluation of the use of a product by a certain user or circle of users. The classical methods for assessing the quality of the human-machine interaction interface and the applicability of experimental and formal methods for assessing quality are considered. The analysis of modern approaches to the design of user interfaces based on UX/UI design is given. An assessment of the requirements and criteria for assessing the user interface from the standpoint of modern design is given. The tasks and features of the UX and UI components of the design process are analyzed. The essence of the modern term “usability” as an indicator of the interface evaluation is explained, and the qualitative evaluation criteria for this indicator are considered. The concept of UX testing is given, the main stages of this process are considered. The importance of taking into account the subjective psychological factors of interface perception is substantiated. The indicators for assessing the quality of user interfaces, based on the cognitive factors of its perception by a person, are analyzed.

Study of Stripping of Membranes at Term Gestation to Reduce Post-Term Pregnancies

Introduction: Any pregnancy which has passed beyond the expected date of delivery is called a prolonged pregnancy &amp; which have passed 42 weeks, 294 days is called postmaturity or post term pregnany [1], these are at an increased risk for fetal postmaturity syndrome, macrosomia, fetal intolerance of labor, oligohydramnios, meconium-stained amniotic fluid, and cesarean delivery [2]. The clinical evidence of an increased potential for these poor perinatal outcomes has triggered a movement toward increased antenatal testing between 37- 42 weeks of gestation, and cervical ripening with labor inductions at or before 42 weeks of gestation. While a ripe cervix is usually suggestive of fetal maturity to find an unripe cervix does not exclude maturity. Induction of labor is one of the most common procedures in obstetrics and is carried out in approximately 20% of pregnancies [3]. Mechanical and biochemical means have been used to affect cervical ripening and to induce labor. Methods of induction include amniotomy, membrane stripping or sweeping, prostaglandins, laminaria and oxytocin. Membrane stripping or sweeping is a commonly use procedure aimed at preventing the post term pregnancy and avoid the application of formal method of induction of labour. Aims and Objectives: 1. to determine the effectiveness &amp; safety of membrane stripping at term pregnancy as a OPD procedure weekly which can reduce the incidence of Post term pregnancy, labour induction and its complication. 2. To determine what factors occurring after digital separation of the chorionic membranes from the lower uterine segment (membrane stripping) are involved in observed clinical changes compared with patients not so treated. Material and Methods: Study Design: This was a prospective study conducted at department of Obstetrics and Gynaecology at our hospital. Study Duration: Study was conducted during the period of duration September 2014 to September 2016. Results: After documenting the confirm gestational dating criteria and obtaining inform consent 200 patients at 37 complete week of gestation were randomly selected for the study. Data were collected from findings at 1,2,3 week and during labour, which is compaired by pearson chi-square and fischer exact test. Conclusion: Stripping of membranes is a very old procedure. This causes the release of plasma prostaglandin F2, Increase in endocervical phospholipase A activity and oxytocin release have also been observed. This will initiate uterine contraction and onset of labour. It is safe, cheap, effective and even an out patient procedure. It is associated with earlier delivery and decreased incidence of posterm gestation and hence maternal and fetal complication related to post maturity.

Verification of Air Data Computer Software using Formal Methods

With the rapid development of airborne system and software, the requirement of software’s robustness, adaptability and reliability improves continually. Failure of software function may cause severe property loss and personnel casualties. Formal methods are mathematically based techniques for the specification, development, and verification of software aspects of digital systems that have obvious advantages in improving safety and reliability of airborne software. This paper takes Air Data Computer software as an example for formal verification in the whole software development process including requirements process, design process, coding process and integration process to demonstrate a set of formal methods application in the airborne software verification process.