Tools and Algorithms for the Construction and Analysis of Systems

This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

Tools and Algorithms for the Construction and Analysis of Systems

This open access book constitutes the proceedings of the 28th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2022, which was held during April 2-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 46 full papers and 4 short papers presented in this volume were carefully reviewed and selected from 159 submissions. The proceedings also contain 16 tool papers of the affiliated competition SV-Comp and 1 paper consisting of the competition report. TACAS is a forum for researchers, developers, and users interested in rigorously based tools and algorithms for the construction and analysis of systems. The conference aims to bridge the gaps between different communities with this common interest and to support them in their quest to improve the utility, reliability, exibility, and efficiency of tools and algorithms for building computer-controlled systems

Temporal verification with transition invariants

Program verification increases the degree of confidence that a program will perform correctly. Manual verification is an error-prone and tedious task. Its automation is highly desirable. The verification methodology reduces the reasoning about temporal properties of program computations to testing the validity of implication between auxiliary first-order assertions. The synthesis of such auxiliary assertions is the main challenge for automated tools. There already exist successful tools for the verification of safety properties. These properties require that some "bad'; states never appear during program computations. The tools construct invariants, which are auxiliary assertions for safety. Invariants are computed symbolically by applying techniques of abstract interpretation. Liveness properties require that some "good'; states will eventually appear in every computation. The synthesis of auxiliary assertions for the verification of liveness properties is the next challenge for automated verification tools. This dissertation argues that transition invariants can provide a new basis for the development of automated methods for the verification of liveness properties. We support this thesis as follows. We introduce a new notion of auxiliary assertions called transition invariant. We apply this notion to propose a proof rule for the verification of liveness properties. We provide a viable approach for the automated synthesis of transition invariants by abstract interpretation, which automates the proof rule. For this purpose, we introduce a transition predicate abstraction. This abstraction does not have an inherent limitation to preserve only safety properties. Most liveness properties of concurrent programs only hold under certain assumptions on non-deterministic choices made during program executions. These assumptions are known as fairness requirements. A direct treatment of fairness requirements in a proof rule is desirable. We specialize our proof rule for the direct accounting of two common ways of specifying fairness. Fairness requirements can be imposed either on program transitions or on sets of programs states. We treat both cases via abstract-transition programs and labeled transition invariants respectively. We have developed a basis for the construction of automated tools that can not only prove that a program never does anything bad, but can also prove that the program eventually does something good. Such proofs increase our confidence that the program will perform correctly.Programmverifikation stärkt unsere Überzeugung darin, dass ein Programm korrekt funktionieren wird. Manuelle Verifikation ist fehleranfällig und mühsam. Deren Automatisierung ist daher sehr erwünscht. Die allgemeine Vorgehensweise bei der Verifikation besteht darin, die temporale Argumentation über die Programmberechnungen auf die Überprüfung der Gültigkeit von Implikation zwischen Hilfsaussagen in Prädikatenlogik zu reduzieren. Die größte Herausforderung in der Automatisierung von Verifikationsmethoden liegt in der automatischen Synthese solcher Hilfsaussagen. Es gibt bereits erfolgreiche Werkzeuge für die automatische Verifikation von Safety-Eigenschaften.Diese Eigenschaften erfordern, dass keine ';unerwünschten" Programmzustände in Berechnungen auftreten. Die Werkzeuge synthetisieren Invarianten, die Hilfsaussagen für die Verifikation von Safety-Eigenschaften darstellen. Invarianten werden symbolisch, mit Hilfe von Techniken der abstrakten Interpretation berechnet. Liveness-Eigenschaften erfordern, dass bestimmte ';gute" Zustände irgendwann in jeder Berechnung vorkommen. Die Synthese von Hilfsaussagen für die Verifikation von Liveness-Eigenschaften ist die nächste Herausforderung für automatische Werkzeuge. Diese Dissertation vertritt die Auffassung, dass Transitionsinvarianten (engl.: transition invariants) eine neu Basis für die Entwicklung automatischer Methoden für die Verifikation von Liveness-Eigenschaften bereitstellen können. Wir unterstützen diese These wie folgt. Wir führen einen neuen Typ von Hilfsaussagen ein, der als Transitionsinvariante bezeichnet wird. Wir benutzen Transitionsinvariante, um eine Beweisregel für die Verifikation von Liveness-Eigenschaften zu entwickeln.Wir stellen einen praktikablen Ansatz für die Synthese von Transitionsinvarianten basierend auf der abstrakten Interpretation vor und automatisieren dadurch die Beweisregel. Zu diesem Zweck führen wir eine Transitionsprädikaten-Abstraktion (engl.: transition predicate abstraction) ein. Diese Abstraktion ist nicht darauf beschränkt, nur Safety-Eigenschaften erhalten zu können. Die meisten Liveness-Eigenschaften nebenläufiger Programme gelten nur unter bestimmten Annahmen bzgl. der nicht-deterministischen Wahl, die bei den Programmberechnungen getroffen wird. Diese Annahmen sind als Fairness-Anforderungen bekannt und deren direkte Berücksichtigung in einer Beweisregel ist wünschenswert. Wir spezialisieren unsere Beweisregel für die direkte Behandlung von zwei verbreiteten Arten von Fairness-Spezifikationen. Zum einem berücksichtigen wir die Fairness-Anforderungen an Programmübergänge durch abstrakte Transitionsprogramme (engl.: abstract-transition programs). Zum anderen werden die durch Zustandsmengen angegebenen Fairness-Anforderungen mit Hilfe von markierten Transitionsinvarianten (engl.: labeled transition invariants) behandelt. Wir haben eine Basis für die Entwicklung automatischer Werkzeuge bereitgestellt, die beweisen können, dass ein Programm nicht schadet und dass das Programm etwas Gutes bewirkt. Solche Beweise stärken unsere Überzeugung darin, dass das Programm korrekt funktionieren wird

Succinct progress measures for solving parity games

The recent breakthrough paper by Calude et al. has given the first algorithm for solving parity games in quasi-polynomial time, where previously the best algorithms were mildly subexponential. We devise an alternative quasi-polynomial time algorithm based on progress measures, which allows us to reduce the space required from quasi-polynomial to nearly linear. Our key technical tools are a novel concept of ordered tree coding, and a succinct tree coding result that we prove using bounded adaptive multi-counters, both of which are interesting in their own right

Criojo: A Pivot Language for Service-Oriented Computing - The Introspective Chemical Abstract Machine

Interoperability remains a significant challenge in service-oriented computing. After proposing a pivot architecture to solve three interoperability problems, namely adaptation, integration and coordination problems between clients and servers, we explore the theoretical foundations for this architecture. A pivot architecture requires a universal language for orchestrating services and a universal language for interfacing resources. Since there is no evidence today that Web Services technologies can provide this basis, we propose a new language called Criojo and essentially show that it can be considered as a pivot language. We formalize the language Criojo and its operational semantics, by resorting to a chemical abstract machine, and give an account of formal translations into Criojo: in a distributed context, we deal with idiomatic languages for four major programming paradigms: imperative programming, logic programming, functional programming and concurrent programming

Programming Languages and Systems

This open access book constitutes the proceedings of the 30th European Symposium on Programming, ESOP 2021, which was held during March 27 until April 1, 2021, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2021. The conference was planned to take place in Luxembourg and changed to an online format due to the COVID-19 pandemic. The 24 papers included in this volume were carefully reviewed and selected from 79 submissions. They deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems

Programming Languages and Systems

This open access book constitutes the proceedings of the 29th European Symposium on Programming, ESOP 2020, which was planned to take place in Dublin, Ireland, in April 2020, as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2020. The actual ETAPS 2020 meeting was postponed due to the Corona pandemic. The papers deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems