9661135
Reasoning about Object-Z specifications
This paper presents a method of reasoning about Object-Z specifications. The approach utilises the modularity inherent in Object-Z specifications to simplify proofs. Properties proved for a class in isolation can be used when that class is either inherited by another class or instantiated as part of a system of interacting objects. Proofs using structural induction and the notion of object integrity are discussed.
671422
Specifying Mode Requirements of Embedded Systems
This paper presents a formal notation for specifying requirements of embedded systems which exhibit continuous, real-time behaviour and move through various modes under digital control. It does this by extending an existing formal notation supporting continuous, real-time behaviour with an explicit concept of modes. The resulting notation avoids the subtleties which would otherwise arise when specifying mode-related requirements. It is therefore ideal as a means of specifying and communicating requirements of embedded systems.
6921917
Recursive Schema Definitions in Object-Z
Unlike Z, Object-Z allows schemas to be defined recursively. This enables mutual and self recursive structures, commonly occurring in object-oriented programs, to be readily specified. In this paper, we provide a fixed point interpretation of such definitions. In addition, we provide simple guidelines for producing non-recursive schema definitions which are semantically identical to recursive ones.
594379
Extending W for Object-Z
This paper presents a logic for Object-Z which extends W, the logic for Z adopted as the basis of the deductive system in the Z Base Standard. The logic provides a basis on which tool support for reasoning about Object-Z specifications can be developed. It also formalises the intended meaning of Object-Z constructs and hence provides an abstract, axiomatic semantics of the language.
18204246
Model checking Object-Z classes: Some experiments with FDR
This paper investigates model checking Object-Z classes via their translation to the input notation of the CSP model checker FDR. Such a translation must not only be concerned with preserving the semantics of the original specification, but also with how efficiently the resulting specification can be model checked. Hence, the paper investigates alternative translation schemes and compares how efficiently the resulting specifications can be checked.
8767817
Incremental Development of Real-Time Requirements: The Light Control Case Study
System requirements frequently change while the system is still under development. Usually this means going back and revising the requirements specification and redoing those development steps already completed. In this article we show how formal requirements can be allowed to evolve while system development is in progress, without the need for costly redevelopment. This is done via a formalism which allows requirements engineering steps to be interleaved with formal development steps in a manageable way. The approach is demonstrated by a significant case study, the Light Control System.
42279258
A Unified Paradigm for Parallel Genetic Algorithms
Genetic Algorithms contain natural parallelism. There are two main approaches in parallelising GAs. The first one is parallelising individual functional components of a standard, sequential GA. The only difference with the sequential GA is in the computation speed. The second approach more closely resembles the real life simultaneous evolution of species, which is the central theme in GAs. Algorithms following this approach are still referred to as GAs but are different from Holland's standard GA. For these algorithms it is not the improvement in computation speed that is the driving factor, but the efficiency with which they search a given solution space. We describe a number of the most common parallel GA methods found in the literature and mention practical issues concerning their implementation in a Transputer based system. We go on to introduce the Unified Parallel GA system, based on our GA toolkit, GAmeter, which allows the user to select one or more of the GA methods described, by setting various parameters. Finally we present results for the Steiner tree Problem in Graphs (SPG).
41530585
Computer Games Have Words, Too: Dialogue Conventions in Final Fantasy VII
1479807
The large-display user experience
The PC's increasing graphical-processing power is fueling a demand for larger and more capable display devices. Several operating systems have supported work with multiple displays for some time. This fact, coupled with graphic-card advancements has led to an increase in multiple monitor (multimon) use. Large displays offer users significant benefits and usability challenges. In this article the authors discuss those challenges along with novel techniques to address these issues.