STRICT: a language and tool set for the design of very large scale integrated circuits

PhD ThesisAn essential requirement for the design of large VLSI circuits is a design methodology which would allow the designer to overcome the complexity and correctness issues associated with the building of such circuits. We propose that many of the problems of the design of large circuits can be solved by using a formal design notation based upon the functional programming paradigm, that embodies design concepts that have been used extensively as the framework for software construction. The design notation should permit parallel, sequential, and recursive decompositions of a design into smaller components, and it should allow large circuits to be constructed from simpler circuits that can be embedded in a design in a modular fashion. Consistency checking should be provided as early as possible in a design. Such a methodology would structure the design of a circuit in much the same way that procedures, classes, and control structures may be used to structure large software systems. However, such a design notation must be supported by tools which automatically check the consistency of the design, if the methodology is to be practical. In principle, the methodology should impose constraints upon circuit design to reduce errors and provide' correctness by construction' . It should be possible to generate efficient and correct circuits, by providing a route to a large variety of design tools commonly found in design systems: simulators, automatic placement and routing tools, module generators, schematic capture tools, and formal verification and synthesis tools

NASA Formal Methods Workshop, 1990

The workshop brought together researchers involved in the NASA formal methods research effort for detailed technical interchange and provided a mechanism for interaction with representatives from the FAA and the aerospace industry. The workshop also included speakers from industry to debrief the formal methods researchers on the current state of practice in flight critical system design, verification, and certification. The goals were: define and characterize the verification problem for ultra-reliable life critical flight control systems and the current state of practice in industry today; determine the proper role of formal methods in addressing these problems, and assess the state of the art and recent progress toward applying formal methods to this area

Formal methods and digital systems validation for airborne systems

This report has been prepared to supplement a forthcoming chapter on formal methods in the FAA Digital Systems Validation Handbook. Its purpose is as follows: to outline the technical basis for formal methods in computer science; to explain the use of formal methods in the specification and verification of software and hardware requirements, designs, and implementations; to identify the benefits, weaknesses, and difficulties in applying these methods to digital systems used on board aircraft; and to suggest factors for consideration when formal methods are offered in support of certification. These latter factors assume the context for software development and assurance described in RTCA document DO-178B, 'Software Considerations in Airborne Systems and Equipment Certification,' Dec. 1992

Applications of formal methods in engineering

The main idea presented in this thesis is to propose and justify a general framework for the development of safety-related systems based on a selection of criticality and the required level of integrity. We show that formal methods can be practically and consistently introduced into the system design lifecycle without incurring excessive development cost. An insight into the process of generating and validating a formal specification from an engineering point of view is illustrated, in conjunction with formal definitions of specification models, safety criteria and risk assessments. Engineering specifications are classified into two main classes of systems, memoryless and memory bearing systems. Heuristic approaches for specification generation and validation of these systems are presented and discussed with a brief summary of currently available formal systems and their supporting tools. It is further shown that to efficiently address different aspects of real-world problems, the concept of embedding one logic within another mechanised logic, in order to provide mechanical support for proofs and reasoning, is practical. A temporal logic framework, which is embedded in Higher Order Logic, is used to verify and validate the design of a real-time system. Formal definitions and properties of temporal operators are defined in HOL and real-time concepts such as timing marker, interrupt and timeout are presented. A second major case study is presented on the specification a solid model for mechanical parts. This work discusses the modelling theory with set theoretic topology and Boolean operations. The theory is used to specify the mechanical properties of large distribution transformers. Associated mechanical properties such as volumetric operations are also discussed

Integrated Formal Analysis of Timed-Triggered Ethernet

We present new results related to the verification of the Timed-Triggered Ethernet (TTE) clock synchronization protocol. This work extends previous verification of TTE based on model checking. We identify a suboptimal design choice in a compression function used in clock synchronization, and propose an improvement. We compare the original design and the improved definition using the SAL model checker

Component library retrieval using property models

The re-use of products such as code, specifications, design decisions and documentation has been proposed as a method for increasing software productivity and reliability. A major problem that has still to be adequately solved is the storage and retrieval of re-usable 'components'. Current methods, such as keyword retrieval and catalogues, rely on the use of names to describe components or categories. This is inadequate for all but a few well established components and categories; in the majority of cases names do not convey sufficient information on which to base a decision to retrieve. One approach to this problem is to describe components using a formal specification. However this is impractical for two reasons; firstly, the limitations of theorem proving would severely restrict the complexity of components that could be retrieved and secondly the retrieval mechanism would need to have a method of retrieving components with 'similar' specifications. This thesis proposes the use of formal 'property' models to represent the key functionality of components. Retrieval of components can then take place on the basis of a property model produced by the library's users. These models only describe the key properties of a component, thereby making the task of comparing properties feasible. Views are introduced as a method of relating similar, non identical property models, and the use of these views facilitates the re-use of components with similar properties. The language Miramod has been developed for the purpose of describing components, and a Miramod compiler and property prover which allow Miramod models to be compared for similarity, have been designed and implemented. These tools have indicated that model based component library retrieval is feasible at relatively low levels of the programming process, and future work is suggested to extend the method to encompass earlier stages in the development of large systems

Proceedings of the 1994 Monterey Workshop, Increasing the Practical Impact of Formal Methods for Computer-Aided Software Development: Evolution Control for Large Software Systems Techniques for Integrating Software Development Environments

Office of Naval Research, Advanced Research Projects Agency, Air Force Office of Scientific Research, Army Research Office, Naval Postgraduate School, National Science Foundatio

On the engineering of crucial software

The various aspects of the conventional software development cycle are examined. This cycle was the basis of the augmented approach contained in the original grant proposal. This cycle was found inadequate for crucial software development, and the justification for this opinion is presented. Several possible enhancements to the conventional software cycle are discussed. Software fault tolerance, a possible enhancement of major importance, is discussed separately. Formal verification using mathematical proof is considered. Automatic programming is a radical alternative to the conventional cycle and is discussed. Recommendations for a comprehensive approach are presented, and various experiments which could be conducted in AIRLAB are described

Formal Methods Specification and Analysis Guidebook for the Verification of Software and Computer Systems

This guidebook, the second of a two-volume series, is intended to facilitate the transfer of formal methods to the avionics and aerospace community. The 1st volume concentrates on administrative and planning issues [NASA-95a], and the second volume focuses on the technical issues involved in applying formal methods to avionics and aerospace software systems. Hereafter, the term "guidebook" refers exclusively to the second volume of the series. The title of this second volume, A Practitioner's Companion, conveys its intent. The guidebook is written primarily for the nonexpert and requires little or no prior experience with formal methods techniques and tools. However, it does attempt to distill some of the more subtle ingredients in the productive application of formal methods. To the extent that it succeeds, those conversant with formal methods will also nd the guidebook useful. The discussion is illustrated through the development of a realistic example, relevant fragments of which appear in each chapter. The guidebook focuses primarily on the use of formal methods for analysis of requirements and high-level design, the stages at which formal methods have been most productively applied. Although much of the discussion applies to low-level design and implementation, the guidebook does not discuss issues involved in the later life cycle application of formal methods