The Temporal Logic Of Reactive And Concurrent Systems

Reactive systems are computing systems which are interactive, such as real-time systems, operating systems, concurrent systems, control systems, etc. They are among the most difficult computing systems to program. Temporal logic is a formal tool/language which yields excellent results in specifying reactive systems. This volume, the first of two, subtitled Specification, has a self-contained introduction to temporal logic and, more important, an introduction to the computational model for reactive programs, developed by Zohar Manna and Amir Pnueli of Stanford University and the Weizmann Institute of Science, Israel, respectively.

The cooperation test [Apt, Francez & de Roever] was originally conceived to capture the proof theoretical analogue of distributed message exchange between disjoint processes, as opposed to the interference freedom test [Owicki & Gries], being the proof theoretical analogue of concurrent communication by means of interference through jointly shared variables. Some authors ([Levin & Gries, Lamport & Schneider, Schlichting and Schneider]) stress that both forms of communication can be proof theoretically characterized using interference freedom only, since proofs for both ultimately amount to an invariance proof of a big global assertion [Ashcroft], invariance of whose parts amounts to interference freedom. Yet I feel that the characteristic nature of the cooperation test is still preserved in the analysis of these authors, because in their analysis of CSP the part dealing with interference freedom specializes to maintenance of a global invariant, the expression of which requires per process the introduction of auxiliary variables which are updated in that process only, thus preserving the concept of disjointness (as opposed to sharing), since now all variables from different processes are disjoint. The cooperation test has been applied to characterize concurrent communication as occurring in Hoare's Communicating Sequential Processes (CSP) [Hoare 2], Ichbiah's ADA [ARM], and Brinch Hansen's Distributed Processes (DP) [Brinch Hansen]. This characterization has been certified through soundness and completeness proofs [Apt 2, Gerth]. As in the interference freedom test this characterization consists of two stages, a local sequential stage and a global stage.

This book is about the verification of reactive systems. A reactive system is a system that maintains an ongoing interaction with its environment, as opposed to computing some final value on termination. The family of reactive systems includes many classes of programs whose correct and reliable construction is con sidered to be particularly challenging, including concurrent programs, embedded and process control programs, and operating systems. Typical examples of such systems are an air traffic control system, programs controlling mechanical devices such as a train, or perpetually ongoing processes such as a nuclear reactor. With the expanding use of computers in safety-critical areas, where failure is potentially disastrous, correctness is crucial. This has led to the introduction of formal verification techniques, which give both users and designers of software and hardware systems greater confidence that the systems they build meet the desired specifications. Framework The approach promoted in this book is based on the use of temporal logic for specifying properties of reactive systems, and develops an extensive verification methodology for proving that a system meets its temporal specification. Reactive programs must be specified in terms of their ongoing behavior, and temporal logic provides an expressive and natural language for specifying this behavior. Our framework for specifying and verifying temporal properties of reactive systems is based on the following four components: 1. A computational model to describe the behavior of reactive systems. The model adopted in this book is that of a Fair Transition System (FTS).

This book presents five tutorial-style lectures on various approaches to the problem of verifying distributed systems: three chapters concentrate on linear-time or branching-time temporal logics; one addresses process equivalence with an emphasis on infinite-state systems; and the final one presents a novel category-theoretic approach to verification. The various formalisms for expressing properties of concurrent systems, based on automata-theoretic techniques or structural properties, are studied in detail. Much attention is paid to the style of writing and complementary coverage of the relevant issues. Thus these lecture notes are ideally suited for advanced courses on logics for concurrent systems. Equally, they are indispensable reading for anyone researching the area of distributed computing.

This book constitutes the proceedings of the 20th International Conference on Tools and Algorithms for the Construction and Analysis of Systems, TACAS 2014, which took place in Grenoble, France, in April 2014, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2014. The total of 42 papers included in this volume, consisting of 26 research papers, 3 case study papers, 6 regular tool papers and 7 tool demonstrations papers, were carefully reviewed and selected from 161 submissions. In addition the book contains one invited contribution. The papers are organized in topical sections named: decision procedures and their application in analysis; complexity and termination analysis; modeling and model checking discrete systems; timed and hybrid systems; monitoring, fault detection and identification; competition on software verification; specifying and checking linear time properties; synthesis and learning; quantum and probabilistic systems; as well as tool demonstrations and case studies.

The REX School/Symposium "A Decade of Concurrency - Reflections and Perspectives" was the final event of a ten-year period of cooperation between three Dutch research groups working on the foundations of concurrency. Ever since its inception in 1983, the goal of the project has been to contribute to the cross-fertilization between formal methods from the fields of syntax, semantics, and proof theory, aimed at an improved understanding of the nature of parallel computing. The material presented in this volume was prepared by the lecturers (and their coauthors) after the meeting took place. In total, the volume constitutes a thorough state-of-the-art report of the research activities in concurrency.

Concurrency and distribution have become the dominant paradigm and concern in computer science. Despite the fact that much of the early research in object-oriented programming focused on sequential systems, objects are a natural unit of distribution and concurrency - as elucidated early on by research on the Actor model. Thus, models and theories of concurrency, the oldest one being Petri nets, and their relation to objects are an attractive topic of study. This book presents state-of-the-art results on Petri nets and concurrent object-oriented programming in a coherent and competent way. The 24 thoroughly reviewed and revised papers are organized in three sections. The first consists of long papers, each presenting a detailed approach to integrating Petri nets and object-orientation. Section II includes shorter papers with emphasis on concrete examples to demonstrate the approach. Finally, section III is devoted to papers which significantly build on the Actor model of computation.