Recently a number of studies have demonstrated that search engine logfiles are an important resource to determine the relevance relation between URLs and query terms. We hypothesized that the queries associated with a URL could also be presented as useful URL metadata in a search engine result list, e.g. for helping to determine the semantic category of a URL. We evaluated this hypothesis by a classification experiment based on the DMOZ dataset. Our method can also annotate URLs that have no associated queries.

The amount of information available to us via the Web has increased enormously over the last few years. Even more, it seems that we are more and more dependent on this Web information in our day to day lives. Often we retrieve this information by querying the Web: data resources found on the web may provide the information that we are looking for. This implies that the Web may be seen as an information market: authors supply information and searchers may find it. In this article we present a formal reference model for the syntactic aspects of the information market. We explore the information landscape using a modeling approach. An important part of this model is a (syntactic) framework for transformations, which allows us to deal with the heterogeneity of the data resources found on the Web. Last but not least, we attempt to give an outline how our model may lead to a better understanding of how information is supplied via the Web. For this we use an example from the field of information retrieval.

Traditionally, information retrieval aims to find information carriers, such as documents, that best match some query or some other (intentional) description of a searcher's information need. In this article, we take the approach that searchers turn to an information retrieval system with the aim of finding several alternatives that completely satisfy their (complex) information need. In other words, searchers expect the retrieval system to help them in covering their information need, rather than merely providing them with a myriad of hopefully relevant information carriers. Ideally, the system should respond by advising one or more packages of information carriers with the requested cumulative effect. This also enables searchers to better trade off between the costs of acquiring and reading/internalizing information carriers versus the expected informational benefits. This article focuses on a theory that aims to clarify the underlying problem area. The theory may consequently be used to enhance information retrieval systems in general and teaching and learning systems in particular, with abilities to better cover a searcher's information need. In the theory presented, we also cater to the fact that searchers may be in different mental moods. The consequence of searchers being in different moods is that information carriers are processed differently. Identifying this influence gives the opportunity to advise users according to their specific moods. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 1155–1188, 2007.

In this paper, the incremental searcher satisfaction model for information retrieval is introduced. In this new model, documents are not only presented according to decreasing relevancy, but also on the level of novelty in the context of the documents previously presented. Documents which are judged to be insufficiently surprising (according to a searcher determined threshold) are not presented to the searcher. This is especially useful for information retrieval in certain contexts (e.g. Internet applications such as search engines), when a searcher does not want all relevant documents to be shown, but to only gain a global idea of the variety of what the corpus may contain on a topic. Important properties of this model are discussed, such as the relation between the reductional effect and the order of presentation.

In recent years, a number of proposals have been made to extend conventional conceptual data modeling techniques with concepts for modeling complex object structures. Among the most prominent proposed concepts is the concept of collection type. A collection type is an object type of which the instances are sets of instances of another object type. A drawback of the introduction of such a new concept is that the formal definition of the technique involved becomes considerably more complex. In this paper a new kind of constraint, the extensional uniqueness constraint, is introduced, providing an alternative treatment of complex object types. The formal definition of this constraint type is presented, the advantages of its introduction are discussed, and its consequences for, among others, identification schemes are elaborated.

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 abstraction mechanism for logbook instances, leading to object-oriented analysis models.

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 systems; 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.

Random search trees have the property that their depth depends on the order in which they are built. They have to be balanced in order to obtain a more efficient storage-and-retrieval data structure. Balancing a search tree is time consuming. This explains the popularity of data structures which approximate a balanced tree but have lower amortized balancing costs, such as AVL trees, Fibonacci trees and 2–3 trees. The algorithms for maintaining these data structures efficiently are complex and hard to derive. This observation has led to insertion algorithms that perform local balancing around the newly inserted node, without backtracking on the search path. This is also called a fringe heuristic. The resulting class of trees is referred to as 1-locally balanced trees, in this note referred to as hairy trees. In this note a simple analysis of their behaviour is provided.

Provides a general theory for evolving information systems. This theory makes a distinction between the underlying information structure at the conceptual level, its evolution on the one hand, and the description and semantics of operations on the information structure and its population on the other hand. The main issues within this theory are object typing, type relatedness and identification of objects. In terms of these concepts, we propose some axioms on the well-formedness of evolution. In this general theory, the underlying data model is a parameter, making the theory applicable for a wide range of modelling techniques, including object-role modelling and object-oriented techniques.

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.

In this article the Uniquest Algorithm (the ‘quest for uniqueness’), defined in the Predicator Model, is discussed in depth. The Predicator Model is a general platform for object-role models. The Uniquest Algorithm is a constructive formal definition of the semantics of uniqueness constraints. As such, it facilitates the implementation in so-called CASE-tools. The Uniquest Algorithm provides a systematic approach for the interpretation of complex uniqueness constraints. This interpretation process is easily traced, using an extra formalism, called the Object Relation Network (ORN). The ORN is a directed graph with labelled edges, representing an object-role information structure. Intermediate results that are outside the scope of the information structure at hand, are represented elegantly as an ORN. A number of theoretical and practical examples prove the power of the Uniquest Algorithm. In these examples we will encounter complex uniqueness constraints, that are missed easily. The Uniquest Algorithm provides a handle for recognition.

This paper concerns the didactic use of refinements and pointer rotation in the derivation of iterative traversal algorithms according to a given specification. The concept of tree transformation provides a high-level view on (non-recursive) tree traversal. Tree transformations can be realised by using the concept of pointer rotation.