T. P. van der Weide

Stratified hypermedia structures for information disclosure

In this paper we generalise the two-level approach to hypertext (hypermedia) systems into stratified hypermedia structures. First we describe the overall architecture of such systems, including the fundamentals of the user interface. Thereafter, its various components are discussed. Special emphasis is paid on how the underlying information model is layered. Two layers are featured: the hyperbase and the hyperindex. A characterisation calculus is presented for the characterisation of structured elements. This calculus forms the basis of a logic-based approach in connection with the associated information processor (Disclosure Machine). The logic-based approach is considered as the most general approach to the retrieval process. In addition, this calculus is useful for quality assurance in hypermedia applications. Attention is also paid to spatial coherence for relevance judgements.

Query Formulation as an Information Retrieval Problem

Query formulation in the context of large conceptual schemata is known to be a hard problem. When formulating ad hoc queries users may become overwhelmed by the vast amount of information that is stored in the information system; leading to a feeling of lost in conceptual space. In this article we develop a strategy to cope with this problem. This strategy is based on ideas from the information retrieval world, in particular the query by navigation mechanism and the stratified hypermedia architecture. The stratified hypermedia architecture is used to describe the information contained in the information system on multiple levels of abstraction. When using our approach to the formulation of queries, a user will first formulate a number of simple queries corresponding to linear paths through the information structure. The formulation of the linear paths is the result of the explorative phase of query formulation. Once users have specified a number of these linear paths, they may combine them to form more complex queries. This last process is referred to as query by construction and corresponds to the constructive phase of the query formulation process.

Formalization techniques: chopping down the methodology jungle

Abstract The formalization of techniques in the context of information system development methodologies is discussed. When such methodologies are developed, the primary goal is applicability. After the methodology has proved itself in practice, it will be applied in more sophisticated situations, pushing it to its limits. In those cases, informal definitions are known to be inappropriate. Some typical problems are considered. After that, a procedure for proper formalization is described. The Predicator Model is presented as an extended example. Finally, some experiences with this approach to formalization are discussed.

Exploring modelling strategies in a meta-modelling context

We are concerned with a core aspect of the processes of obtaining conceptual models We view such processes as information gathering dialogues, in which strategies may be followed (possibly, imposed) in order to achieve certain modelling goals Many goals and strategies for modelling can be distinguished, but the current discussion concerns meta-model driven strategies, aiming to fulfil modelling goals or obligations that are the direct result of meta-model choices (i.e the chosen modelling language) We provide a rule-based conceptual framework for capturing strategies for modelling, and give examples based on a simplified version of the Object Role Modelling (ORM) meta-model We discuss strategy rules directly related to the meta-model, and additional procedural rules We indicate how the strategies may be used to dynamically set a modelling agenda Finally, we describe a generic conceptual structure for a strategy catalog.

The modelling and retrieval of documents using index expressions

In this paper we introduce Index Expressions as a means for modelling document content. From an index expression the the Power Index Expression can be derived, which is a powerful instrument for information retrieval. We describe the characterization of documents in the style of formal logic. The content of a document is then modelled by a set of axioms, of which the document is a model. Relating a document to a query is done by proving the query from the axioms of that document. We introduce three rules of inference. If such a proof is not possible, the relevance of the document for the query is derived by plausible deduction. We introduce two inference rules for plausible deduction.

Applications of a categorical framework for conceptual data modeling

Abstract. For successful information systems development, conceptual data modeling is essential. Nowadays a plethora of techniques for conceptual data modeling exist. Many of these techniques lack a formal foundation and a lot of theory, e.g. concerning updates or schema transformations, is highly data model specific. As such there is a need for a unifying formal framework providing a sufficiently high level of abstraction. In this paper, focus is on the applications of such a framework defined in category theory. Well-known conceptual data modeling concepts, such as relationship types, generalization, specialization, and collection types are defined from a categorical point of view in this framework and an essential advantage is its “configurable semantics”. Features such as null values, uncertainty, and temporal behavior can be added by selecting appropriate instance categories. The addition of these features usually requires a complete redesign of the formalization in traditional set-based approaches to semantics. Applications of the framework in the context of schema transformations and improved automated modeling support are discussed.

Information Modeling: The Process and the Required Competencies of Its Participants

In recent literature it is commonly agreed that the first phase of the software development process is still an area of concern. Furthermore, while software technology has been changed and improved rapidly, the way of working and managing this process have remained behind.

Object-Oriented Modelling based on Logbooks

In this paper the notion of logbook is introduced as a common basis for various models to be produced during system analysis. A logbook has a unifying format which contains a complete description of the history of some Universe of Discourse. It is intended as a structuring mechanism for initial specifications based on natural language. A typing mechanism is provided as an ion mechanism for logbook instances, leading to object-oriented analysis models.

Quality makes the information market

In this paper we consider information exchange via the Web to be an information market The notion of quality plays an important role on this information market We present a model of quality and discuss how this model can be operationalized. This leads us to quality measurement, interpretation of measurements and the associated accuracy An illustration in the form of a basic quality assessment system is presented.

Effectiveness of index expressions

The quest for improving retrieval performance has led to the deployment of larger syntactical units than just plain words. This article presents a retrieval experiment that compares the effectiveness of two unsupervised language models which generate terms that exceed the word boundary. In particular, this article tries to show that index expressions provide, beside their navigational properties, a good way to capture the semantics of inter-word relations and by doing so, form an adequate base for information retrieval applications.