Construction of formal models and verifying property specifications through an example of railway interlocking systems

Abstract The use of formal modeling has seen an increasing interest in the development of safety-critical, embedded microcomputer-controlled railway interlocking systems, due to its ability to specify the behavior of the systems using mathematically precise rules. The research goal is to prepare a specification-verification environment, which supports the developer of the railway interlocking systems in the creation of a formally-proven correct design and at the same time hides the inherent mathematical-computer since related background knowledge. The case study is presented with the aim to summarize the process of formalizing a domain specification, and to show further application possibilities (e.g. verification methods)

Improving Saturation-based Bounded Model Checking

Formal verification is becoming a fundamental step in assuring the correctness of safety-critical systems. Since these systems are often asynchronous and even distributed, their verification requires methods that can deal with huge or even infinite state spaces. Model checking is one of the current techniques to analyse the behaviour of systems, as part of the verification process. In this paper a symbolic bounded model checking algorithm is presented that relies on efficient saturation-based methods. The previous approaches are extended with new bounded state space exploration strategies. In addition, constrained saturation is also introduced to improve the efficiency of bounded model checking. Our measurements confirm that these approaches do not only offer a solution to deal with infinite state spaces, but in many cases they even outperform the original methods

Bounded saturation-based CTL model checking

Formal verification is becoming a fundamental step of safety-critical and model-based software development. As part of the verification process, model checking is one of the current advanced techniques to analyze the behavior of a system. Symbolic model checking is an efficient approach to handling even complex models with huge state spaces. Saturation is a symbolic algorithm with a special iteration strategy, which is efficient for asynchronous models. Recent advances have resulted in many new kinds of saturation-based algorithms for state space generation and bounded state space generation and also for structural model checking. In this paper, we examine how the combination of two advanced model checking algorithms – bounded saturation and saturation-based structural model checking – can be used to verify systems. Our work is the first attempt to combine these approaches, and this way we are able to handle and examine complex or even infinite state systems. Our measurements show that we can exploit the efficiency of saturation in bounded model checking

Formal Modeling and Verification of the Functionality of Electronic Urban Railway Control Systems Through a Case Study

This paper presents a formal model-based methodology to support railway engineers in the design of safe electronic urban railway control systems. The purpose of our research is to overcome the deficiencies of existing traditional design methodologies, namely the incompleteness and the potential presence of contradictions in the system specification resulting from non-formal development techniques. We illustrate the application of the methodology via a case study of a tram-road level crossing protection system. It was chosen partly because it has a simple architecture and a small number of elements, thus it fits the scope limitations of this article. At the same time, it is suitable for presenting all essential features of our methodology. The proposed solution provides a specification/verification environment that facilitates the construction of correct, complete, consistent, and verifiable functional specifications during the development, while hiding all the formal method-related details from the railway engineers writing the specifications. Using this formal model-based methodology, a high-quality functional specification can be achieved, which is guaranteed to be more exhaustive and will contain fewer errors than traditional development

A Rövidített Pozitív Élmények Feldolgozási Módjai Skála magyar változatának reliabilitás- és validitásvizsgálata

Elméleti háttér: A pozitív élmények átélése során megjelenő érzéseinket különböző módokon dolgozhatjuk fel. Különbséget tehetünk az élmények intenzitását növelő és csökkentő reakciók között. Cél: Tanulmányunkban bemutatjuk a Rövidített Pozitív Élmények Feldolgozási Módjai Skála magyar változatának (WOSC-H) reliabilitás- és validitásvizsgálatát. A kérdőív azokat a kognitív és viselkedéses reakciókat vizsgálja, amelyeket pozitív élmények átélése közben adhatunk. Módszer: Keresztmetszeti vizsgálatunkban 596 fő (296 férfi, 300 nő) töltötte ki a kérdőívcsomagot. A skála validitásának vizsgálatára a boldogsággal kapcsolatos orientáció, az élettel való elégedettség, illetve a vitalitás mérőeszközeit alkalmaztuk. Eredmények: A skála főkomponens-elemzése két komponens jelenlétét mutatta: a pozitív élményekbe Bevonódó, illetve a pozitív élményektől Eltávolodó élményfeldolgozást. A kérdőív megfelelő reliabilitású, azonban a kétkomponensű modell illeszkedési mutatói csak közepes szintűek. Az egyes faktorok az elvárt irányú összefüggést mutatták a validálóskálákkal. Következtetések: Összességében a skála a pozitív élményekre adott reakciók megbízható és valid mérőeszközének bizonyult. | Background: Our emotions during positive experiences can be processed in different ways. We can make a distinction between reactions that increase and reactions that decrease the intensity of the experience. Aim: The aim of our study was to present the adaptation of the Hungarian version of the Abridged Ways of Savoring Checklist (WOSC). This scale measures the potential cognitive and behavioral responses during positive experiences. Method: Data from our cross-sectional study (N = 596, 296 male, 300 female) are analyzed. To examine the validity of the scale, we used instruments measuring orientation to happiness, satisfaction with life, and vitality. Results: The principal component analysis revealed 2 components: savoring positive experiences versus dampening positive experiences. The reliability of the scale is good, but the goodness of fit of the two-component model was weak. The validity of the scale proved to be adequate: savoring positive experiences goes with higher level of positive mental health indicators, while dampening positive experiences goes with lower level of positive mental health indicators. Conclusions: The Hungarian version of WOSC is a useful measure of the reactions during positive experiences