Modeling And Verification Of Real Time Systems

This title is devoted to presenting some of the most important concepts and techniques for describing real-time systems and analyzing their behavior in order to enable the designer to achieve guarantees of temporal correctness. Topics addressed include mathematical models of real-time systems and associated formal verification techniques such as model checking, probabilistic modeling and verification, programming and description languages, and validation approaches based on testing. With contributions from authors who are experts in their respective fields, this will provide the reader with the state of the art in formal verification of real-time systems and an overview of available software tools.

system is a complex object containing a significant percentage of elec A tronics that interacts with the Real World (physical environments, humans, etc. ) through sensing and actuating devices. A system is heterogeneous, i. e. , is characterized by the co-existence of a large number of components of disparate type and function (for example, programmable components such as micro processors and Digital Signal Processors (DSPs), analog components such as AID and D/A converters, sensors, transmitters and receivers). Any approach to system design today must include software concerns to be viable. In fact, it is now common knowledge that more than 70% of the development cost for complex systems such as automotive electronics and communication systems are due to software development. In addition, this percentage is increasing constantly. It has been my take for years that the so-called hardware-software co-design problem is formulated at a too low level to yield significant results in shorten ing design time to the point needed for next generation electronic devices and systems. The level of abstraction has to be raised to the Architecture-Function co-design problem, where Function refers to the operations that the system is supposed to carry out and Architecture is the set of supporting components for that functionality. The supporting components as we said above are heteroge neous and contain almost always programmable components.

This book collects the research work of leading-edge researchers and practitioners in the areas of analysis, synthesis, design and implementation of real-time systems with applications in various industrial fields. Their works are grouped into six parts, together encompassing twenty chapters. Each part is devoted to a mainstream subject, the chapters therein developing one of the major aspects of real-time system theory, modeling, design, and practical applications. Starting with a general approach in the area of formalization of real-time systems, and setting the foundations for a general systemic theory of those systems, the book covers everything from building modeling frameworks for various types of real-time systems, to verification, and synthesis. Other parts of the book deal with subjects related to tools and applications of these systems. A special part is dedicated to languages used for their modeling and design. The applications presented in the book reveal precious insights into practitioners' secrets.

This book presents the lecture notes of the 1st Summer School on Methods and Tools for the Design of Digital Systems, 2015, held in Bremen, Germany. The topic of the summer school was devoted to modeling and verification of cyber-physical systems. This covers several aspects of the field, including hybrid systems and model checking, as well as applications in robotics and aerospace systems. The main chapters have been written by leading scientists, who present their field of research, each providing references to introductory material as well as latest scientific advances and future research directions. This is complemented by short papers submitted by the participating PhD students.

The research described in this monograph concerns the formal specification and compositional verification of real-time systems. A real-time programminglanguage is considered in which concurrent processes communicate by synchronous message passing along unidirectional channels. To specifiy functional and timing properties of programs, two formalisms are investigated: one using a real-time version of temporal logic, called Metric Temporal Logic, and another which is basedon extended Hoare triples. Metric Temporal Logic provides a concise notationto express timing properties and to axiomatize the programming language, whereas Hoare-style formulae are especially convenient for the verification of sequential constructs. For both approaches a compositional proof system has been formulated to verify that a program satisfies a specification. To deduce timing properties of programs, first maximal parallelism is assumed, modeling the situation in which each process has itsown processor. Next, this model is generalized to multiprogramming where several processes may share a processor and scheduling is based on priorities. The proof systems are shown to be sound and relatively complete with respect to a denotational semantics of the programming language. The theory is illustrated by an example of a watchdog timer.

Formal verification means having a mathematical model of a system, a language for specifying desired properties of the system in a concise, comprehensible and unambiguous way, and a method of proof to verify that the specified properties are satisfied. When the method of proof is carried out substantially by machine, we speak of automatic verification. Symbolic Model Checking deals with methods of automatic verification as applied to computer hardware. The practical motivation for study in this area is the high and increasing cost of correcting design errors in VLSI technologies. There is a growing demand for design methodologies that can yield correct designs on the first fabrication run. Moreover, design errors that are discovered before fabrication can also be quite costly, in terms of engineering effort required to correct the error, and the resulting impact on development schedules. Aside from pure cost considerations, there is also a need on the theoretical side to provide a sound mathematical basis for the design of computer systems, especially in areas that have received little theoretical attention.

Models that include a notion of time are ubiquitous in disciplines such as the natural sciences, engineering, philosophy, and linguistics, but in computing the abstractions provided by the traditional models are problematic and the discipline has spawned many novel models. This book is a systematic thorough presentation of the results of several decades of research on developing, analyzing, and applying time models to computing and engineering. After an opening motivation introducing the topics, structure and goals, the authors introduce the notions of formalism and model in general terms along with some of their fundamental classification criteria. In doing so they present the fundamentals of propositional and predicate logic, and essential issues that arise when modeling time across all types of system. Part I is a summary of the models that are traditional in engineering and the natural sciences, including fundamental computer science: dynamical systems and control theory; hardware design; and software algorithmic and complexity analysis. Part II covers advanced and specialized formalisms dealing with time modeling in heterogeneous software-intensive systems: formalisms that share finite state machines as common “ancestors”; Petri nets in many variants; notations based on mathematical logic, such as temporal logic; process algebras; and “dual-language approaches” combining two notations with different characteristics to model and verify complex systems, e.g., model-checking frameworks. Finally, the book concludes with summarizing remarks and hints towards future developments and open challenges. The presentation uses a rigorous, yet not overly technical, style, appropriate for readers with heterogeneous backgrounds, and each chapter is supplemented with detailed bibliographic remarks and carefully chosen exercises of varying difficulty and scope. The book is aimed at graduate students and researchers in computer science, while researchers and practitioners in other scientific and engineering disciplines interested in time modeling with a computational flavor will also find the book of value, and the comparative and conceptual approach makes this a valuable introduction for non-experts. The authors assume a basic knowledge of calculus, probability theory, algorithms, and programming, while a more advanced knowledge of automata, formal languages, and mathematical logic is useful.

Time is a fascinating subject and has long since captured mankind's imagination, from the ancients to modern man, both adult and child alike. It has been studied across a wide range of disciplines, from the natural sciences to philosophy and logic. Today, thirty plus years since Prior's work in laying out foundations for temporal logic, and two decades on from Pnueli's seminal work applying of temporal logic in specification and verification of computer programs, temporal logic has a strong and thriving international research community within the broad disciplines of computer science and artificial intelligence. Areas of activity include, but are certainly not restricted to: Pure Temporal Logic, e. g. temporal systems, proof theory, model theory, expressiveness and complexity issues, algebraic properties, application of game theory; Specification and Verification, e. g. of reactive systems, ofreal-time components, of user interaction, of hardware systems, techniques and tools for verification, execution and prototyping methods; Temporal Databases, e. g. temporal representation, temporal query ing, granularity of time, update mechanisms, active temporal data bases, hypothetical reasoning; Temporal Aspects in AI, e. g. modelling temporal phenomena, in terval temporal calculi, temporal nonmonotonicity, interaction of temporal reasoning with action/knowledge/belief logics, temporal planning; Tense and Aspect in Natural Language, e. g. models, ontologies, temporal quantifiers, connectives, prepositions, processing tempo ral statements; Temporal Theorem Proving, e. g. translation methods, clausal and non-clausal resolution, tableaux, automata-theoretic approaches, tools and practical systems.