GUESSING, MODEL CHECKING AND THEOREM PROVING OF STATE MACHINE PROPERTIES – A CASE STUDY ON QLOCK

It is worth understanding state machines better because various kinds of systems can be formalized as state machines and therefore understanding state machines has something to do with comprehension of systems. Understanding state machines can be interpreted as knowing properties they enjoy and comprehension of systems is interpreted as knowing whether they satisfy requirements. We (mainly the second author) have developed a tool called SMGA that basically takes a finite sequence of states from a state machine and generates a graphical animation of the finite sequence or the state machine. Observing such a graphical animation helps us guess properties of the state machine. We should confirm whether the state machine enjoys the guessed properties because such guessed properties may not be true properties of the state machine. Model checking is one possible technique to do so. If the state machine has a fixed small number of reachable states, model checking is enough. Otherwise, however, it is not. If that is the case, we should use some other techniques to make sure that the system enjoys the guessed properties. Interactive theorem proving is one such technique. The paper reports on a case study in which a mutual exclusion protocol called Qlock is used as an example to exemplify the abovementioned idea or methodology

Twenty years of rewriting logic

AbstractRewriting logic is a simple computational logic that can naturally express both concurrent computation and logical deduction with great generality. This paper provides a gentle, intuitive introduction to its main ideas, as well as a survey of the work that many researchers have carried out over the last twenty years in advancing: (i) its foundations; (ii) its semantic framework and logical framework uses; (iii) its language implementations and its formal tools; and (iv) its many applications to automated deduction, software and hardware specification and verification, security, real-time and cyber-physical systems, probabilistic systems, bioinformatics and chemical systems

Complementary formalisms - synthesis, verification and visualization

Ph.DDOCTOR OF PHILOSOPH

Mathematics in Software Reliability and Quality Assurance

This monograph concerns the mathematical aspects of software reliability and quality assurance and consists of 11 technical papers in this emerging area. Included are the latest research results related to formal methods and design, automatic software testing, software verification and validation, coalgebra theory, automata theory, hybrid system and software reliability modeling and assessment

Coalgebraic Methods for Object-Oriented Specification

This thesis is about coalgebraic methods in software specification and verification. It extends known techniques of coalgebraic specification to a more general level to pave the way for real world applications of software verification. There are two main contributions of the present thesis: 1. Chapter 3 proposes a generalisation of the familiar notion of coalgebra such that classes containing methods with arbitrary types (including binary methods) can be modelled with these generalised coalgebras. 2. Chapter 4 presents the specification language CCSL (short for Coalgebraic Class Specification Language), its syntax, its semantics, and a prototype compiler that translates CCSL into higher-order logic.Die Dissertation beschreibt coalgebraische Mittel und Methoden zur Softwarespezifikation und -verifikation. Die Ergebnisse dieser Dissertation vereinfachen die Anwendung coalgebraischer Spezifikations- und Verifikationstechniken und erweitern deren Anwendbarkeit. Damit werden Softwareverifikation im Allgemeinen und im Besonderen coalgebraische Methoden zur Softwareverifikation der praktischen Anwendbarkeit ein Stück nähergebracht. Diese Dissertation enthält zwei wesentliche Beiträge: 1. Im Kapitel 3 wird eine Erweiterung des klassischen Begriffs der Coalgebra vorgestellt. Diese Erweiterung erlaubt die coalgebraische Modellierung von Klassenschnittstellen mit beliebigen Methodentypen (insbesondere mit binären Methoden). 2. Im Kapitel 4 wird die coalgebraische Spezifikationssprache CCSL (Coalgebraic Class Specification Language) vorgestellt. Die Bescheibung umfasst Syntax, Semantik und einen Prototypcompiler, der CCSL Spezifikationen in Logik höherer Ordnung (passend für die Theorembeweiser PVS und Isabelle/HOL) übersetzt

Heterogeneous verification of model transformations

Esta tesis trata sobre la verificación formal en el contexto de la Ingeniería Dirigida por Modelos (MDE por sus siglas en inglés). El paradigma propone un ciclo de vida de la ingeniería de software basado en una abstracción de su complejidad a través de la definición de modelos y en un proceso de construcción (semi)automático guiado por transformaciones de estos modelos. Nuestro propósito es abordar la verificación de transformaciones de modelos la cual incluye, por extensión, la verificación de sus modelos. Comenzamos analizando la literatura relacionada con la verificación de transformaciones de modelos para concluir que la heterogeneidad de las propiedades que interesa verificar y de los enfoques para hacerlo, sugiere la necesidad de utilizar diversos dominios lógicos, lo cual es la base de nuestra propuesta. En algunos casos puede ser necesario realizar una verificación heterogénea, es decir, utilizar diferentes formalismos para la verificación de cada una de las partes del problema completo. Además, es beneficioso permitir a los expertos formales elegir el dominio en el que se encuentran más capacitados para llevar a cabo una prueba formal. El principal problema reside en que el mantenimiento de múltiples representaciones formales de los elementos de MDE en diferentes dominios lógicos, puede ser costoso si no existe soporte automático o una relación formal clara entre estas representaciones. Motivados por esto, definimos un entorno unificado que permite la verificación formal transformaciones de modelos mediante el uso de métodos de verificación heterogéneos, de forma tal que es posible automatizar la traducción formal de los elementos de MDE entre dominios logicos. Nos basamos formalmente en la Teoría de Instituciones, la cual proporciona una base sólida para la representación de los elementos de MDE (a través de instituciones) sin depender de ningúningún dominio lógico específico. También proporciona una forma de especificar traducciones (a través de comorfismos) que preservan la semántica entre estos elementos y otros dominios lógicos. Nos basamos en estándares para la especificación de los elementos de MDE. De hecho, definimos una institución para la buena formación de los modelos especificada con una versión simplificada del MetaObject Facility y otra institución para transformaciones utilizando Query/View/Transformation Relations. No obstante, la idea puede ser generalizada a otros enfoques de transformación y lenguajes.Por último, demostramos la viabilidad del entorno mediante el desarrollo de un prototipo funcional soportado por el Heterogeneous Tool Set (HETS). HETS permite realizar una especificación heterogénea y provee facilidades para el monitoreo de su corrección global. Los elementos de MDE se conectan con otras lógicas ya soportadas en HETS (por ejemplo: lógica de primer orden, lógica modal, entre otras) a través del Common Algebraic Specification Language (CASL). Esta conexión se expresa teóricamente mediante comorfismos desde las instituciones de MDE a la institución subyacente en CASL. Finalmente, discutimos las principales contribuciones de la tesis. Esto deriva en futuras líneas de investigación que contribuyen a la adopción de métodos formales para la verificación en el contexto de MDE.This thesis is about formal verification in the context of the Model-Driven Engineering (MDE) paradigm. The paradigm proposes a software engineering life-cycle based on an abstraction from its complexity by defining models, and on a (semi)automatic construction process driven by model transformations. Our purpose is to address the verification of model transformations which includes, by extension, the verification of their models. We first review the literature on the verification of model transformations to conclude that the heterogeneity we find in the properties of interest to verify, and in the verification approaches, suggests the need of using different logical domains, which is the base of our proposal. In some cases it can be necessary to perform a heterogeneous verification, i.e. using different formalisms for the verification of each part of the whole problem. Moreover, it is useful to allow formal experts to choose the domain in which they are more skilled to address a formal proof. The main problem is that the maintenance of multiple formal representations of the MDE elements in different logical domains, can be expensive if there is no automated assistance or a clear formal relation between these representations. Motivated by this, we define a unified environment that allows formal verification of model transformations using heterogeneous verification approaches, in such a way that the formal translations of the MDE elements between logical domains can be automated. We formally base the environment on the Theory of Institutions, which provides a sound basis for representing MDE elements (as so called institutions) without depending on any specific logical domain. It also provides a way for specifying semantic-preserving translations (as so called comorphisms) from these elements to other logical domains. We use standards for the specification of the MDE elements. In fact, we define an institution for the well-formedness of models specified with a simplified version of the MetaObject Facility, and another institution for Query/View/Transformation Relations transformations. However, the idea can be generalized to other transformation approaches and languages. Finally, we evidence the feasibility of the environment by the development of a functional prototype supported by the Heterogeneous Tool Set (HETS). HETS supports heterogeneous specifications and provides capabilities for monitoring their overall correctness. The MDE elements are connected to the other logics already supported in HETS (e.g. first-order logic, modal logic, among others) through the Common Algebraic Specification Language (CASL). This connection is defined by means of comorphisms from the MDE institutions to the underlying institution of CASL. We carry out a final discussion of the main contributions of this thesis. This results in future research directions which contribute with the adoption of formal tools for the verification in the context of MDE

The 2020 Expert Survey on Formal Methods

International audienc