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Item An Approach to Hierarchical Input Devices(Blackwell Publishing Ltd and the Eurographics Association, 1990) Duce, D. A.; Liere, R van; Hagen, P.J.W. tenThis paper shows how a formal description of the GKS input model can be extended to include hierarchically structured input devicesItem Concerning the Specification of User Interfaces(Blackwell Publishing Ltd and the Eurographics Association, 1985) Duce, D. A.Item Better Understanding through Formal Specification(Blackwell Publishing Ltd and the Eurographics Association, 1985) Duce, D. A.; Fielding, E. V. C.The Graphical Kernel System (GKS) is now registered as an ISO International Standard for computer graphics programming. One of the major innovations of the Standard is the bundled specification of aspects, a mechanism which gives the applications programmer the ability to tailor the appearance of a picture independently on each of the workstations on which it is displayed, using the capabilities of the workstations. GKS also incorporates the traditional method of individual specification of aspects in which each workstation does the best it can to represent global aspect values. In this paper a formal specification technique, the Vienna Development Method (VDM), is used to describe aspect specification. The GKS model of aspect specification is progressively constructed from simpler models. Properties of these simpler models are formulated and the specifications are proved to conform to these. The properties are then traced through the more complex models. The paper demonstrates the applicability of formal specification to the design of graphics software and the ability of formal techniques to catalyse the deeper understanding of designs.Item GKS-9x: The Design Output Primitive, an Approach to a Specification.(Blackwell Science Ltd and the Eurographics Association, 1994) Nehlig, Ph. W.; Duce, D. A.This paper describes an approach to the formal definition of the design primitive introduced in the revision of the ISO/IEC computer graphics standard, GKS. The paper starts with a general description of the design primitive and then describes the specification (which is given in the Z notation) and the motivation for the approach taken in some detail. The paper concludes with a reflection on the contribution of this work, and the descriptive style adopted an the GKS revision, to the role of formal description in the presentation of graphics standards.Item Components, Frameworks and GKS Input(Eurographics Association, 1989) Duce, D. A.; Ten Hagen, P.J.W.; Van Liere, R.This paper was inspired by the Components/ Frameworks approach to a Reference Model for computer graphics, currently under discussion in the ISO computer graphics subject committee. The paper shows how a formal description of the GKS input model may be given in Hoare’s CSP notation and explores some extensions in which some of the components in the GKS model are replaced by more interesting ones. The paper thus demonstrates some of the power and flexibility inherent in the Component/ Frameworks idea. The use of a formal notation led to a deepening of the authors’ understanding of the input model and suggested some different ways of looking at the input model.Item A Formal Specification of a Graphics System in the Framework of the Computer Graphics Reference Model(Blackwell Science Ltd and the Eurographics Association, 1993) Duce, D. A.; Paterno, F.This paper is motivated by the emerging ISO/IEC Reference Model for Computer Graphics (CGRM) and the revision of the ISO/IEC computer graphics standard, the Graphical Kernel System (GKS). The paper explores the use of the CGRM as a framework for structuring a specification of apart of the current draft of the revised GKS and the use of the LOTOS formal description technique for specifying graphics systems.Item GKS, Structures and Formal Specification(Eurographics Association, 1989) Duce, D. A.There are now three International Standards for application program interfaces for computer graphics programming, GKS, GKS-3D and PHIGS. In this paper a simplified model GKS-like system is described and a 2D PHIGS-like system is then described in terms of this and a centralized structure store. Formal specifications of the systems are given illustrating how the specification of a system can be built up from a hierarchy of simple components. The purpose of the paper is to illustrate one approach to the description of a compatible family of graphics standards and the use of formal specification techniques in this process.Item Towards a Formal Specification of the GKS Output Primitives(The Eurographics Association, 1986) Duce, D. A.; Fielding, E. V. C.; A.A.G. Requicha