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.
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.
18518522
A Development Framework for Object-Oriented Specification and Refinement
This paper presents a language-independent framework for developing formal speciications in an intuitively object-oriented style. Within the framework, object-oriented concepts and design strategies are captured by the application of development operators. The operators, by eeec-tively hiding the technical details of how object-oriented concepts are captured in a given speci-cation language, allow the speciier to develop speciications in an intuitively object-oriented fashion. They also present a exible approach to object-oriented speciication as libraries of operators can be deened allowing many diierent dee-nitions of object-oriented features to be available. This enables a close mapping to be achieved between the speciication and the implementation in the chosen object-oriented programming language. The framework also records the history of operator application enabling \classes" and \modules" to be identiied in the resulting spec-iications and, hence, the possibility of modular veriication and reenement.
2625360
Abstract Specification in Object-Z and CSP
A number of integrations of the state-based specification language Object-Z and the process algebra CSP have been proposed in recent years. In developing such integrations, a number of semantic decisions have to be made. In particular, what happens when an operation's precondition is not satisfied? Is the operation blocked, i.e., prevented from occurring, or can it occur with an undefined result? Also, are outputs from operations angelic, satisfying the environment's constraints on them, or are they demonic and not influenced by the environment at all? In this paper we discuss the differences between the models, and show that by adopting a blocking model of preconditions together with an angelic model of outputs one can specify systems at higher levels of abstraction.
30219210
Compositional Class Refinement in Object-Z
Object-Z allows coupling constraints between classes which, on the one hand, facilitate specification at a high level of abstraction, but, on the other hand, make class refinement non-compositional. The consequence of this is that refinement is not practical for large systems. This paper overcomes this limitation by introducing a methodology for compositional class refinement in Object-Z. The key step is an equivalence transformation of an arbitrary Object-Z specification to one in which introduced constraints prohibit non-compositional refinements. The methodology also allows the constraints which couple classes to be refined yielding an unrestricted approach to compositional class refinement.
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.
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).
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.
206854015
Fitness Distance Correlation and Ridge Functions
Fitness Distance Correlation has been proposed as a measure of function optimization difficulty. This paper describes a class of functions, named the Ridge Functions which, according to the measure, should be highly misleading. However, all functions tested were optimized easily by both a GA and a simple hill climbing algorithm. Scatter graph analysis of Ridge functions gave little guidance due to the large number of functions with an identical scatter graph, the majority of which are not in the class of Ridge functions and are not simple to optimize.
41530585
Computer Games Have Words, Too: Dialogue Conventions in Final Fantasy VII