Subsequence invariants

In this thesis, we introduce subsequence invariants, a new class of invariants for the specification and verification of systems. Unlike state invariants, which refer to the state variables of the system, subsequence invariants characterize the behavior of a concurrent system in terms of the occurrences of sequences of synchronization events. The first type of such invariants, pure subsequence invariants, are linear constraints over the possible numbers of such occurrences, where we allow every occurrence of a subsequence to be interleaved arbitrarily with other events. We then describe the more general class of phased subsequence invariants, in which additional restrictions can be placed on the events that may occur between those of a given sequence. In either case, subsequence invariants are preserved when a given process is composed with additional processes. subsequence invariants can therefore be computed individually for each process and then be used to reason about the full system. We present an efficient algorithm for the computation of subsequence invariants of finite-state systems. Our construction can be applied incrementally to obtain a growing set of invariants given a growing set of event sequences. We then address the problem of proving subsequence invariants of infinite-state systems. For this we use an abstraction refinement procedure that uses small, incrementally transformed graph-based abstractions. In order to explain the techniques we use, we first introduce a simpler version of this method for statebased properties, and then show how to verify subsequence invariants.Inhalt dieser Arbeit sind Subsequenzinvarianten, eine neue Klasse von Invarianten für die Systemspezifikation und -verifikation. Im Gegensatz zu zustandsbasierten Invarianten, die über den Zustandsvariablen des Systems definiert sind, beschreiben Subsequenzinvarianten das gewünschte Systemverhalten anhand des Auftretens verschiedener Synchronisationsfolgen. Wir beschreiben zunächst reine Subsequenzinvarianten, welche durch lineare Gleichungen auf den möglichen Häufigkeiten solcher Folgen von Events gegeben sind, zwischen denen jeweils beliebige andere Events autreten dürfen. Im Anschluss verallgemeinern wir diese zu Subsequenzinvarianten mit Phasen, in denen eine Synchronisationsfolge neben der eigentlichen Folge von Events auch durch Beschränkungen auf den dazwischen auftretenden Events gegeben sein kann. Beide Klassen von Invarianten bleiben gültig, wenn ein Prozess, für den sie gelten, mit beliebigen anderen Prozessen kombiniert wird. Sie können daher für jeden einzelnen Prozess berechnet und dann zur Verifikation des gesamten Systems verwendet werden. Wir präsentieren einen effizienten Algorithmus für die Berechnung von Subsequenzinvarianten auf Systemen mit endlichen Zustandsräumen. Diese Konstruktion kann auch inkrementell angewandt werden, wenn die Menge der betrachteten Subsequenzen allmählich wächst. Für die Berechnung von Subsequenzinvarianten für Systeme mit unendlichem Zustandsraum führen wir eine Methode ein, die auf dem Prinzip der Abstraktionsverfeinerung basiert. Unsere Version dieses Ansatzes zeichnet sich durch die Verwendung sehr kleiner, graphenbasierter Abstraktionen aus. Wir präsentieren zunächst eine einfachere Variante des Verfahrens für zustandsbasierte Fehlerbedingungen, an der sich die verwendeten Operationen leichter demonstrieren lassen, und beschreiben dann die Anpassungen für die Verifikation von Subsequenzinvarianten

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

Computer Aided Verification

The open access two-volume set LNCS 11561 and 11562 constitutes the refereed proceedings of the 31st International Conference on Computer Aided Verification, CAV 2019, held in New York City, USA, in July 2019. The 52 full papers presented together with 13 tool papers and 2 case studies, were carefully reviewed and selected from 258 submissions. The papers were organized in the following topical sections: Part I: automata and timed systems; security and hyperproperties; synthesis; model checking; cyber-physical systems and machine learning; probabilistic systems, runtime techniques; dynamical, hybrid, and reactive systems; Part II: logics, decision procedures; and solvers; numerical programs; verification; distributed systems and networks; verification and invariants; and concurrency

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

Computer Aided Verification

The open access two-volume set LNCS 11561 and 11562 constitutes the refereed proceedings of the 31st International Conference on Computer Aided Verification, CAV 2019, held in New York City, USA, in July 2019. The 52 full papers presented together with 13 tool papers and 2 case studies, were carefully reviewed and selected from 258 submissions. The papers were organized in the following topical sections: Part I: automata and timed systems; security and hyperproperties; synthesis; model checking; cyber-physical systems and machine learning; probabilistic systems, runtime techniques; dynamical, hybrid, and reactive systems; Part II: logics, decision procedures; and solvers; numerical programs; verification; distributed systems and networks; verification and invariants; and concurrency

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

Computer Aided Verification

The open access two-volume set LNCS 12224 and 12225 constitutes the refereed proceedings of the 32st International Conference on Computer Aided Verification, CAV 2020, held in Los Angeles, CA, USA, in July 2020.* The 43 full papers presented together with 18 tool papers and 4 case studies, were carefully reviewed and selected from 240 submissions. The papers were organized in the following topical sections: Part I: AI verification; blockchain and Security; Concurrency; hardware verification and decision procedures; and hybrid and dynamic systems. Part II: model checking; software verification; stochastic systems; and synthesis. *The conference was held virtually due to the COVID-19 pandemic

Computer Aided Verification

This open access two-volume set LNCS 11561 and 11562 constitutes the refereed proceedings of the 31st International Conference on Computer Aided Verification, CAV 2019, held in New York City, USA, in July 2019. The 52 full papers presented together with 13 tool papers and 2 case studies, were carefully reviewed and selected from 258 submissions. The papers were organized in the following topical sections: Part I: automata and timed systems; security and hyperproperties; synthesis; model checking; cyber-physical systems and machine learning; probabilistic systems, runtime techniques; dynamical, hybrid, and reactive systems; Part II: logics, decision procedures; and solvers; numerical programs; verification; distributed systems and networks; verification and invariants; and concurrency

Template-based verification of heap-manipulating programs

We propose a shape analysis suitable for analysis engines that perform automatic invariant inference using an SMT solver. The proposed solution includes an abstract template domain that encodes the shape of a program heap based on logical formulae over bit-vectors. It is based on a points-to relation between pointers and symbolic addresses of abstract memory objects. Our abstract heap domain can be combined with value domains in a straight-forward manner, which particularly allows us to reason about shapes and contents of heap structures at the same time. The information obtained from the analysis can be used to prove reachability and memory safety properties of programs manipulating dynamic data structures, mainly linked lists. The solution has been implemented in 2LS and compared against state-of-the-art tools that perform the best in heap-related categories of the well-known Software Verification Competition (SV-COMP). Results show that 2LS outperforms these tools on benchmarks requiring combined reasoning about unbounded data structures and their numerical contents