Integrating BDD-based and SAT-based Symbolic Model Checking

Symbolic model checking is a very successful formal verification technique, classically based on Binary Decision Diagrams (BDDs). Recently, propositional satisfiability (SAT) techniques have been proposed as a computational basis for symbolic model checking, and proved to be an effective alternative to BDD-based techniques. In this paper we show how BDD-based and SAT-based techniques have been effectively integrated within the NuSMV symbolic model checker

Entwicklung eines STPA-Verifiers als Eclipse-Plug-in für die Verifikation von Software-Sicherheitsanforderungen

Um die Sicherheit in kritischen Softwaresystemen zu gewährleisten ist immer häufiger eine Verifikation der Software in einem Systemkontext notwendig. Hierfür ist in den letzten Jahren die Verifikation von Softwaresystemen durch Model Checking, bedingt durch die wachsende Anzahl an dafür zur Verfügung stehenden Werkzeugen, eine bewährte Methode geworden. Diese Arbeit stellt auf Grundlage des in STPA SwISS [AWL15] vorgestellten Konzeptes eine Software zur automatisierten Ausführung von LTL und CTL Model Checking mit den Werkzeugen Spin und NuSMV bietet. Dabei können die Sicherheitsanforderungen sowohl manuell eingegeben werden, als auch aus einer STPA Analyse importiert werden. Das Ergebnis dieser Arbeit soll ein Ansatz zur Kombination einer Gefahrenanalyse auf Systemebene und einer Verifikation dieses Systems auf Implementierungsebene sein. Zu diesem Zweck wird der STPA Verifier zur automatisierten Verifikation von Sicherheitsanforderungen und Dokumentation der Ergebnisse vorgestellt.To verify the safety on a critical softwaresystem includes more and more often the task of verifying Software in the context of the system. In the last years verifying software by using formal model checking has become a more and more popular method due to the increasing number of available tool support. This work presents a Software based on the concepts of the STPA SwISS approach [AWL15] that provides a graphical user interface for performing automated LTL and CTL model checking using the Spin or the NuSMV model checker. The safety properties can be derived either manually or by importing the results of a STPA hazard analysis. The result of this work are supposed to be an approach to combine a hazard analysis on system level and a Softwareverification on implementation level. To provide this the STPA Verifier for verfying safety constraints and creating a verification report is presented

Consistency Checking of Natural Language Temporal Requirements using Answer-Set Programming

Successful software engineering practice requires high quality requirements. Inconsistency is one of the main requirement issues that may prevent software projects from being success. This is particularly onerous when the requirements concern temporal constraints. Manual checking whether temporal requirements are consistent is tedious and error prone when the number of requirements is large. This dissertation addresses the problem of identifying inconsistencies in temporal requirements expressed as natural language text. The goal of this research is to create an efficient, partially automated, approach for checking temporal consistency of natural language requirements and to minimize analysts\u27 workload. The key contributions of this dissertation are as follows: (1) Development of a partially automated approach for checking temporal consistency of natural language requirements. (2) Creation of a formal language Temporal Action Language (TeAL), which provide a means to represent natural language requirements precisely and unambiguously. (3) Development of a front end to semi-automatically translate natural language requirements into TeAL. (4) Development of a translator from TeAL to the ASP language. Validation results to date show that the front end tool makes the task of translating natural language requirements into TeAL more accurate and efficient, and the translator generates ASP programs that correctly detect the inconsistencies in the requirements

SystemC Through the Looking Glass : Non-Intrusive Analysis of Electronic System Level Designs in SystemC

Due to the ever increasing complexity of hardware and hardware/software co-designs, developers strive for higher levels of abstractions in the early stages of the design flow. To address these demands, design at the Electronic System Level (ESL) has been introduced. SystemC currently is the de-facto standard for ESL design. The extraction of data from system designs written in SystemC is thereby crucial e.g. for the proper understanding of a given system. However, no satisfactory support of reflection/introspection of SystemC has been provided yet. Previously proposed methods for this purpose %introduced to achieve the goal nonetheless either focus on static aspects only, restrict the language means of SystemC, or rely on modifications of the compiler and/or parser. In this thesis, approaches that overcome these limitations are introduced, allowing the extraction of information from a given SystemC design without changing the SystemC library or the compiler. The proposed approaches retrieve both, static and dynamic (i.e. run-time) information

Proposta de um método de verificação por tempo global com redes de Petri no desenvolvimento de software embarcado e em tempo real

Resumo: Sistemas embarcados de tempo real são sistemas restritos quanto às funcionalidades e recursos disponíveis. Nesses sistemas, requisitos temporais são tão importantes quanto requisitos funcionais. Nas fases de análise e projeto do software embarcado, um modelo analítico pode auxiliar em atividades de verificação, reduzindo o tempo de desenvolvimento e aumentando a garantia do comportamento correto do sistema. Este trabalho propõe a aplicação da técnica de tempo global de redes de Petri na verificação de software embarcado de tempo real. Um algoritmo da técnica de tempo global foi proposto e implementado. Um método geral de aplicação desta técnica e uma instanciação deste método foram propostos. Modelos de mapeamento de tarefas em redes de Petri foram desenvolvidos e um modelo de geração de cenários de comportamento para a análise de escalonabilidade para as políticas de prioridade fixa e earliest deadline first foi determinado e implementado. A execução e análise de experimentos permitiram observar o método e modelos. O método proposto neste trabalho objetiva identificar cenários de comportamento que não respeitam as restrições temporais do sistema modelado. No caso de sistemas embarcados e em tempo real esta é uma das principais preocupações das equipes de desenvolvimento de software. Como resultado, desenvolvemos um método que permite a verificação temporal de software embarcado de tempo real com relógios global e relativo, que é um passo relevante para facilitar a aplicação de redes de Petri no contexto do desenvolvimento destes sistemas

Nutzerfreundliche Modellierung mit hybriden Systemen zur symbolischen Simulation in CLP

Die Dissertation beinhaltet die Sprachen MODEL-HS und VYSMO zur modularen, deklarativen Beschreibung hybrider Systeme, die dem Nachweis zeit- und sicherheitskritischer Eigenschaften für die symbolische Simulation in CLP dienen. Zum Erlangen sprachtheoretischer Erkenntnisse wie Entscheidbarkeit wurden hybride Systeme neu unter formal nachweisbaren Akzeptanzbedingungen definiert, welche durch praktische Beispiele belegt sind. Weitere Ergebnisse sind eine neue Klassifikation hybrider Systeme, ein Werkzeug ROSSY, Anfragebeschreibungen und deren Transformation in temporal-logische Ausdrücke, Anfragemasken und Anwendungen für Studiensysteme und parallele Programme.The dissertation includes the languages MODEL-HS and VYSMO for modular, declarative description of hybrid systems that serve the proof of time- and safety-critical properties for symbolic simulation in CLP. For coming to language-theoretical conclusions like decidability hybrid systems are newly defined under acceptance conditions that can be formally proved and for which practical examples bear witness. A new classification of hybrid systems, a tool ROSSY, query descriptions and their transformation into temporal-logic expressions, query forms and applications for study systems and parallel programs are further results

Dokumentverifikation mit Temporaler Beschreibungslogik

The thesis proposes a new formal framework for checking the content of web documents along individual reading paths. It is vital for the readability of web documents that their content is consistent and coherent along the possible browsing paths through the document. Manually ensuring the coherence of content along the possibly huge number of different browsing paths in a web document is time-consuming and error-prone. Existing methods for document validation and verification are not sufficiently expressive and efficient. The innovative core idea of this thesis is to combine the temporal logic CTL and description logic ALC for the representation of consistency criteria. The resulting new temporal description logics ALCCTL can - in contrast to existing specification formalisms - compactly represent coherence criteria on documents. Verification of web documents is modelled as a model checking problem of ALCCTL. The decidability and polynomial complexity of the ALCCTL model checking problem is proven and a sound, complete, and optimal model checking algorithm is presented. Case studies on real and realistic web documents demonstrate the performance and adequacy of the proposed methods. Existing methods such as symbolic model checking or XML-based document validation are outperformed in both expressiveness and speed.Die Dissertation stellt ein neues formales Framework für die automatische Prüfung inhaltlich-struktureller Konsistenzkriterien an Web-Dokumente vor. Viele Informationen werden heute in Form von Web-Dokumenten zugänglich gemacht. Komplexe Dokumente wie Lerndokumente oder technische Dokumentationen müssen dabei vielfältige Qualitätskriterien erfüllen. Der Informationsgehalt des Dokuments muss aktuell, vollständig und in sich stimmig sein. Die Präsentationsstruktur muss unterschiedlichen Zielgruppen mit unterschiedlichen Informationsbedürfnissen genügen. Die Sicherstellung grundlegender Konsistenzeigenschaften von Dokumenten ist angesichts der Vielzahl der Anforderungen und Nutzungskontexte eines elektronischen Dokuments nicht trivial. In dieser Arbeit werden aus der Hard-/Softwareverifikation bekannte Model-Checking-Verfahren mit Methoden zur Repräsentation von Ontologien kombiniert, um sowohl die Struktur des Dokuments als auch inhaltliche Zusammenhänge bei der Prüfung von Konsistenzkriterien berücksichtigen zu können. Als Spezifikationssprache für Konsistenzkriterien wird die neue temporale Beschreibungslogik ALCCTL vorgeschlagen. Grundlegende Eigenschaften wie Entscheidbarkeit, Ausdruckskraft und Komplexität werden untersucht. Die Adäquatheit und Praxistauglichkeit des Ansatzes werden in Fallstudien mit eLearning-Dokumenten evaluiert. Die Ergebnisse übertreffen bekannte Ansätze wie symbolisches Model-Checking oder Methoden zur Validierung von XML-Dokumenten in Performanz, Ausdruckskraft hinsichtlich der prüfbaren Kriterien und Flexibilität hinsichtlich des Dokumenttyps und -formats