Synthesis of asynchronous distributed systems from global specifications

The synthesis problem asks whether there exists an implementation for a given formal specification and derives such an implementation if it exists. This approach enables engineers to think on a more abstract level about what a system should achieve instead of how it should accomplish its goal. The synthesis problem is often represented by a game between system players and environment players. Petri games define the synthesis problem for asynchronous distributed systems with causal memory. So far, decidability results for Petri games are mainly obtained for local winning conditions, which is limiting as global properties like mutual exclusion cannot be expressed. In this thesis, we make two contributions. First, we present decidability and undecidability results for Petri games with global winning conditions. The global safety winning condition of bad markings defines markings that the players have to avoid. We prove that the existence of a winning strategy for the system players in Petri games with a bounded number of system players, at most one environment player, and bad markings is decidable. The global liveness winning condition of good markings defines markings that the players have to reach. We prove that the existence of a winning strategy for the system players in Petri games with at least two system players, at least three environment players, and good markings is undecidable. Second, we present semi-decision procedures to find winning strategies for the system players in Petri games with global winning conditions and without restrictions on the distribution of players. The distributed nature of Petri games is employed by proposing encodings with true concurrency. We implement the semi-decision procedures in a corresponding tool.Das Syntheseproblem stellt die Frage, ob eine Implementierung f ¨ur eine Spezifikation existiert, und generiert eine solche Implementierung, falls sie existiert. Diese Vorgehensweise erlaubt es Programmierenden sich mehr darauf zu konzentrieren, was ein System erreichen soll, und weniger darauf, wie die Spezifikation erf ¨ ullt werden soll. Das Syntheseproblem wird oft als Spiel zwischen einem System- und einem Umgebungsspieler dargestellt. Petri-Spiele definieren das Syntheseproblem f ¨ur asynchrone verteilte Systeme mit kausalem Speicher. Bisher wurden Resultate bez¨uglich der Entscheidbarkeit von Petri-Spiele meist f ¨ur lokale Gewinnbedingungen gefunden. In dieser Arbeit pr¨asentieren wir zuerst Resultate bez¨uglich der Entscheidbarkeit und Unentscheidbarkeit von Petri-Spielen mit globalen Gewinnbedingungen. Wir beweisen, dass die Existenz einer gewinnenden Strategie f ¨ur die Systemspieler in Petri- Spielen mit einer beschr¨ankten Anzahl an Systemspielern, h¨ochstens einem Umgebungsspieler und schlechten Markierungen entscheidbar ist. Wir beweisen ebenfalls, dass die Existenz einer gewinnenden Strategie f ¨ur die Systemspieler in Petri-Spielen mit mindestens zwei Systemspielern, mindestens drei Umgebungsspielern und guten Markierungen unentscheidbar ist. Danach pr¨asentieren wir Semi-Entscheidungsprozeduren, um gewinnende Strategien f ¨ur die Systemspieler in Petri-Spielen mit globalen Gewinnbedingungen und ohne Restriktionen f ¨ur die Verteilung von Spielern zu finden. Wir benutzen die verteilte Natur von Petri-Spielen, indem wir Enkodierungen einf ¨uhren, die Nebenl¨aufigkeit ausnutzen. Die Semi-Entscheidungsprozeduren sind in einem entsprechenden Tool implementiert

Computer Aided Verification

This open access two-volume set LNCS 13371 and 13372 constitutes the refereed proceedings of the 34rd International Conference on Computer Aided Verification, CAV 2022, which was held in Haifa, Israel, in August 2022. The 40 full papers presented together with 9 tool papers and 2 case studies were carefully reviewed and selected from 209 submissions. The papers were organized in the following topical sections: Part I: Invited papers; formal methods for probabilistic programs; formal methods for neural networks; software Verification and model checking; hyperproperties and security; formal methods for hardware, cyber-physical, and hybrid systems. Part II: Probabilistic techniques; automata and logic; deductive verification and decision procedures; machine learning; synthesis and concurrency. This is an open access book

Tools and Algorithms for the Construction and Analysis of Systems

This book is Open Access under a CC BY licence. The LNCS 11427 and 11428 proceedings set constitutes the proceedings of the 25th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2019, which took place in Prague, Czech Republic, in April 2019, held as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2019. The total of 42 full and 8 short tool demo papers presented in these volumes was carefully reviewed and selected from 164 submissions. The papers are organized in topical sections as follows: Part I: SAT and SMT, SAT solving and theorem proving; verification and analysis; model checking; tool demo; and machine learning. Part II: concurrent and distributed systems; monitoring and runtime verification; hybrid and stochastic systems; synthesis; symbolic verification; and safety and fault-tolerant 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

Recognition and Exploitation of Gate Structure in SAT Solving

In der theoretischen Informatik ist das SAT-Problem der archetypische Vertreter der Klasse der NP-vollständigen Probleme, weshalb effizientes SAT-Solving im Allgemeinen als unmöglich angesehen wird. Dennoch erzielt man in der Praxis oft erstaunliche Resultate, wo einige Anwendungen Probleme mit Millionen von Variablen erzeugen, die von neueren SAT-Solvern in angemessener Zeit gelöst werden können. Der Erfolg von SAT-Solving in der Praxis ist auf aktuelle Implementierungen des Conflict Driven Clause-Learning (CDCL) Algorithmus zurückzuführen, dessen Leistungsfähigkeit weitgehend von den verwendeten Heuristiken abhängt, welche implizit die Struktur der in der industriellen Praxis erzeugten Instanzen ausnutzen. In dieser Arbeit stellen wir einen neuen generischen Algorithmus zur effizienten Erkennung der Gate-Struktur in CNF-Encodings von SAT Instanzen vor, und außerdem drei Ansätze, in denen wir diese Struktur explizit ausnutzen. Unsere Beiträge umfassen auch die Implementierung dieser Ansätze in unserem SAT-Solver Candy und die Entwicklung eines Werkzeugs für die verteilte Verwaltung von Benchmark-Instanzen und deren Attribute, der Global Benchmark Database (GBD)

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