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.
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.
22030322
Animation of Object-Z specifications using a Z animator
We discuss a methodology for animating the Object-Z specification language using a Z animation environment. Central to the process is the introduction of a framework to handle dynamic instantiation of objects and management of object references. Particular focus is placed upon building the animation environment through pre-existing tools, and a case study is presented that implements the proposed framework using a shallow encoding in the Possum Z animator. The animation of Object-Z using Z is both automated and made transparent to the user through the use of a software tool named O-zone.
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.
12040305
Structural Refinement in Object-Z/CSP
State-based refinement relations have been developed for use on the Object-Z components in an integrated Object-Z / CSP specification. However this refinement methodology does not allow the structure of a specification to be changed in a refinement, whereas a full methodology would allow concurrency to be introduced during the development life-cycle. In this paper we tackle these concerns and discuss refinements of specifications written using Object-Z and CSP where we change the structure of the specification when performing the refinement. In particular, we develop a set of structural simulation rules which allow a single Object-Z component to be refined to a number of communicating or interleaved classes. We prove soundness of these rules and illustrate them with a small example.
17770007
Encoding Object-Z in Isabelle/HOL
In this paper, we present a formalisation of the reference semantics of Object-Z in the higher-order logic (HOL) instantiation of the generic theorem prover Isabelle, Isabelle/HOL. This formalisation has the effect of both clarifying the semantics and providing the basis for a theorem prover for Object-Z. The work builds on an earlier encoding of a value semantics for object-oriented Z in Isabelle/HOL and a denotational semantics of Object-Z based on separating the internal and external effects of class methods.
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.
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).