This paper introduces the Abstract User Interface (AUI) model and notation for specifying abstract interaction in interactive software systems with graphical, direct manipulation user interfaces. The AUI model is aimed at improving the plasticity of an interactive system. An interactive system is considered to be plastic when it is easily adaptable to concrete user interface styles. To support plasticity, an AUI specification defines the interaction between input, output and computation in terms of the abstract elements of the user interface: a relation we refer to as abstract interaction. Concrete characteristics of the user interface, such as events, callbacks and rendering, are deliberately factored out so that the abstract interaction relation can be exposed. Clearly defining the abstract interaction ensures that consistent interaction semantics is maintained independent of changes to the concrete user interface. To demonstrate the AUI concept, a range of user interface styles are presented for a single AUI specification of a drawing tool, and examples of commercial applications are presented.

Declarative debugging is a method of debugging characterized by locating coding errors in a program using knowledge of the program's intended interpretation alone. A declarative debugger (GraDE) for Godel is presented which handles all of Godel's syntax together with support for abstract data types and coroutining. GraDE builds a computation tree for the program and goal, then works with this tree in a flexible way. The soundness and completeness of the debugger is proved. The performance of two well known approaches, top-down and divide-and-query, are compared on practical programs. GraDE also allows users to control the search method directly thus eliminating an automated search method. The implementation of G r aDE in Godel is discussed and proposals are put forward for further work.

Recent research in geographic information systems has been concerned with the construction of algebras to make inferences about spatial relations by embedding spatial relations within a space in which decisions about compositions are derived geometrically. We pursue an alternative approach by studying spatial relations and their inferences in a concrete spatial scenario, a room space that contains such manipulable objects as a box, a ball, a table, a sheet of paper, and a pen. We derive from the observed spatial properties an algebra related to the fundamental spatial concepts of containers and surfaces and show that this container-surface algebra holds all properties of Tarski's relation algebra, except for the associativity. The crispness of the compositions can be refined by considering the relative size of the objects) and their roles (i.e., whether it is explicitly known that the objects are containers or surfaces).

Mere academic toys or the tools of the future? Lazy functional programming languages have undoubted attractive properties. This thesis explores their potential, from the programmer's point of view, for implementing interactive and graphical applications to which they do not seem immediately suited. The discussion is centred round two example applications. One is a graphical design program based on an idea of the artist M. C. Escher. The thesis argues that the graphical user interface may be encapsulated in an "interpret " function that when applied by a mouse click to an interface of appropriate type yields the required behaviour. The second example is a monitoring interpreter for a functional language. The idea is that if the mechanics of the reduction are presented at a suitable level of abstraction, this may be used to give insight into what is going on. On the basis of this the programmer might modify the code so that a program runs more efficiently in terms of speed and memory requirements. Problems of displaying the reduction are addressed, and solutions proposed for overcoming these: displaying the graph as a spanning tree, to ensure planarity, with extra leaves

Abstract not found

cataloguing Information géographique — Méthodologie de catalogage des entités ICS 35.240.70 In accordance with the provisions of Council Resolution 15/1993 this document is circulated in the English language only. Conformément aux dispositions de la Résolution du Conseil 15/1993, ce document est distribué en version anglaise seulement. To expedite distribution, this document is circulated as received from the committee secretariat. ISO Central Secretariat work of editing and text composition will be undertaken at publication stage. Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au Secrétariat central de l'ISO au stade de publication.

This paper addresses the problem of formalizing the natural-language definitions of spatial features. While the Spatial Data Transfer Standard (SDTS) supports the structural aspects of the definition of spatial features, it falls short of providing means to convey explicitly their behaviors. Formal algebraic specifications go beyond the SDTS approach, by providing precise mathematical representations of the behavior of geographic features and the interactions among related feature types. Such functional specifications also help in refining the selection of attributes needed to characterize the behavior of a given feature type. An implication of the functional approach is to provide precise mathematical signatures of feature types as an alternative to natural-language definitions. Such mathematical specifications are unambiguous across cultures and languages and provide a strict basis for assessing the interoperability of objects in feature-based GISs. An approach based on universal algebra is developed using the example of the SDTS standard entity types dam, watercourse, and lake, together with the operations expressed in the natural-language definitions of these features. This example is implemented using the functional language Gofer.

Algebras over spatial relations have become an important aspect of spatial reasoning for retrieving and handling large and complex spatial data sets. While such spatial relations play a fundamental role in specifying constraints in a spatial query language, there has been little concern as to whether existing spatial-relation algebras are cognitively plausible. In order to construct more intuitive and easier-to-use spatial query languages, this work pursues an alternative approach to spatial reasoning based on a small set of operators that derive cognitively plausible spatial relations. The work focuses on a set of operators that are associated with the behavior of image schemata--- recurrent patterns that people learn through bodily experiences and use to assign meaning to objects and situations. A study of a small-scale space, involving the surface and container schemata, describes objects in this space and the possible spatial relations among them. The informal description is then translated into a formal algebraic specification and generalized for spatial relations in a scene that involves surface and container schemata. This formalization axiomatizes spatial inferences that are then applied and compared to a larger geographic space. As a result, a small set of spatial operators were defined for small- and large-scale spaces; however, these operators show discrepancies when applied to a combination of objects belonging to different scales. It is expected that this study can be useful in exploring new theories for the design of query languages of future geographic information systems.