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.
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.
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.
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.
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.
41530585
Computer Games Have Words, Too: Dialogue Conventions in Final Fantasy VII
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.