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.
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.
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.
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.
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.
14865714
Breast Composition Measurements Using Retrospective Standard Mammogram Form (SMF)
The standard mammogram form (SMF) representation of an x-ray mammogram is a standardized, quantitative representation of the breast from which the volume of non-fat tissue and breast density can be easily estimated, both of which are of significant interest in determining breast cancer risk. Previous theoretical analysis of SMF had suggested that a complete and substantial set of calibration data (such as mAs and kVp) would be needed to generate realistic breast composition measures and yet there are many interesting trials that have retrospectively collected images with no calibration data. The main contribution of this paper is to revisit our previous theoretical analysis of SMF with respect to errors in the calibration data and to show how and why that theoretical analysis did not match the results from the practical implementations of SMF. In particular, we show how by estimating breast thickness for every image we are, effectively, compensating for any errors in the calibration data. To illustrate our findings, the current implementation of SMF (version 2.2beta) was run over 4028 digitized film-screen mammograms taken from six sites over the years 1988-2002 with and without using the known calibration data. Results show that the SMF implementation running without any calibration data at all generates results which display a strong relationship with when running with a complete set of calibration data, and, most importantly, to an expert's visual assessment of breast composition using established techniques. SMF shows considerable promise in being of major use in large epidemiological studies related to breast cancer which require the automated analysis of large numbers of films from many years previously where little or no calibration data is available.
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.