IRIS Research Publications


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Journal

F.C. Berger, and T.W.C. Huibers. A Framework based on Situation Theory for Searching in a Thesaurus. In: Journal of Text and Document Management, Vol: 1, Pages: 253-276, 1995.

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P. van Bommel. Database design by computer-aided schema transformations. In: Software Engineering Journal, Nr: 4, Vol: 10, Pages: 125-132, July, 1995.

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G.H.W.M. Bronts, S.J. Brouwer, C.L.J. Martens, and H.A. (Erik) Proper. A Unifying Object Role Modelling Approach. In: Information Systems, Nr: 3, Vol: 20, Pages: 213-235, 1995.

This article presents the idea of defining a kernel for object role modelling techniques, upon which different drawing styles can be based. We propose such a kernel (the ORM kernel) and define, as a case study, an ER and a NIAM drawing style on top of it.

One of the prominent advantages of such a kernel is the possibility to build a CASE-tool supporting multiple methods. Such a CASE-tool would allow users with different methodological backgrounds to use it and view the modelled domains in terms of their favourite method. This is illustrated using a running example of a concrete domain in which we use the ORM kernel in combination with the NIAM and ER drawing style.

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T.A. Halpin, and H.A. (Erik) Proper. Subtyping and Polymorphism in Object-Role Modelling. In: Data & Knowledge Engineering, Vol: 15, Pages: 251-281, 1995.

Although Entity-Relationship (ER) modelling techniques are commonly used for information modelling, Object-Role Modelling (ORM) techniques are becoming increasingly popular, partly because they include detailed design procedures providing guidelines for the modeller. As with the ER approach, a number of different ORM techniques exist. In this paper, we propose an integration of two theoretically well founded ORM techniques: FORM and PSM.

Our main focus is on a common terminological framework, and on the notion of subtyping. Subtyping has long been an important feature of semantic approaches to conceptual schema design. It is also the concept in which FORM and PSM differ the most in their formalization. The subtyping issue is discussed from three different viewpoints covering syntactical, identification, and population issues. Finally, a wider comparison of approaches to subtyping is made, which encompasses other ER-based and ORM-based information modelling techniques, and highlights how formal subtype definitions facilitate a comprehensive specification of subtype constraints.

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C.H.A. Koster, and Th.P. van der Weide. Hairy Search Trees. In: The Computer Journal, Nr: 8, Vol: 38, Pages: 691-694, 1995.

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 amortised 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 povided.

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H.A. (Erik) Proper, and Th.P. van der Weide. Information Disclosure in Evolving Information Systems: Taking a shot at a moving target. In: Data & Knowledge Engineering, Vol: 15, Pages: 135-168, 1995.

In this paper, we introduce a query language for evolving information systems. Evolving information systems go beyond the capacity of conventional database systems, not only as they incorporate a time dimension, but also since they allow all aspects of the system to evolve.

The introduced language is related to the philosophy underlying NIAM (Natural language Information Analysis Method). This method investigates the grammar of the communication in the Universe of Discourse. Usually this grammar is depicted as an information structure diagram (NIAM or ER schema).

This paper describes the language Elisa-D, which is based on this grammar. As a result, expressions in this language have a direct meaning in the universe of discourse, while natural language expressions are easily formalised in this language.

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H.A. (Erik) Proper, and Th.P. van der Weide. A General Theory for the Evolution of Application Models. In: IEEE Transactions on Knowledge and Data Engineering, Nr: 6, Vol: 7, Pages: 984-996, December, 1995.

In this article we focus on evolving information systems. First a delimitation of the concept of evolution is provided, resulting in a first attempt to a general theory for such evolutions.

The 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. 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.

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Book

P. van Bommel. Database Optimization: An Evolutionary Approach. University of Nijmegen, 1995, ISBN 9090082441.

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Conference

F.C. Berger, and Th.P. van der Weide. A Feedback Mechanism for Query by Navigation. In: Proceedings of the Sixth Australasian Database Conference, ADC`95, Edited by: R. Sacks-Davis, and J. Zobel. Australian Computer Science Communications, Vol: 17(2), Pages: 56-65, January, 1995.

The Two-Level Hypermedia Paradigm sees an Information Retrieval System as consisting of a document network (the Hyperbase) and a descriptor (term) network (the Hyperindex). Query by Navigation is a process whereby the searcher gives a description of the Information Need by travelling through the descriptor network. This paper presents a formalism for expressing the effects of traversing the Hyperindex on the elements of the Hyperindex. This formalism makes use of probabilities for modelling the searcher's behavious. The events which can occur during the search process are discussed and modelled. Some important properties, which are reasonable to demand of a retrieval system, can be proven to be valid if this formalism is adopted. A mechanism for assigning a measure of relevance to documents is presented. This uses the formalism mentioned above. An example will show the effectiveness of The aspect of relevance feedback and its role in Query by Navigation is introduced by examining the different level on which the searcher can offer information for weeding out unwanted sections of the search space. In order to illustrate the workings of Query by Navigation a small example is included.

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T.A. Halpin, and H.A. (Erik) Proper. Database schema transformation and optimization. In: Proceedings of the OOER`95, 14th International Object-Oriented and Entity-Relationship Modelling Conference, Gold Coast, Queensland, Australia, Edited by: M.P. Papazoglou. Lecture Notes in Computer Science, Vol: 1021, Pages: 191-203, December, Springer, 1995, ISBN 3540606726.

An application structure is best modelled first as a conceptual schema, and then mapped to an internal schema for the, conceptual schemas often map to different internal schemas, so performance may be improved by applying conceptual transformations prior to the standard mapping.

This paper discusses recent advances in theory of schema transformation and optimization within the framework of ORM (Object-Role Modelling). New aspects include object relativity, complex types, a high level transformation language and update distributivity.

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A.H.M. ter Hofstede, H.A. (Erik) Proper, and Th.P. van der Weide. Computer Supported Query Formulation in an Evolving Context. In: Proceedings of the Sixth Australasian Database Conference, ADC`95, Edited by: R. Sacks-Davis, and J. Zobel. Australian Computer Science Communications, Vol: 17(2), Pages: 188-202, January, 1995.

Even if high-level query languages are used, query formulation may cause problems. This is notably so in case of large and complex application domains. Typical examples of these kinds of application domains are evolving application domains. In an evolving application domain not only populations may change, but also the conceptual schema. Even more, the history of the application domain should be recorded, and be retrievable.

This paper focuses on support for query formulation in the context of large conceptual schemata. The solution presented uses the idea of query-by-navigation in conjunction with query-by-construction. First this idea is illustrated by means of some examples, then it is formally defined.

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J.J. Sarbo, and J.I. Farkas. Knowledge representation and acquisition by concept lattices. In: Proceedings of the 11th Israeli Symposium on Artificial Intelligence (ISAI`95), Edited by: S. Markovitch. 1995.

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Reports

N.E. van Oosterom, and J.W.G.M. Hubbers. Het FOP-project vanuit RSO-perspectief. Technical report, ABN/AMRO-bank, The Netherlands, 1995, In Dutch.

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P.D. Bruza, and T.W.C. Huibers. How nonmonotonic is aboutness?. Technical report, March, Department of Computer Science, Utrecht University, The Netherlands, 1995.

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P.J.M. Frederiks, and Th.P. van der Weide. Fundamentals of Object Orientation in KISS. Technical report: CSI-N9601, May, Computing Science Institute, University of Nijmegen, 1995.

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P.J.M. Frederiks, C.H.A. Koster, and Th.P. van der Weide. Object-Oriented Analysis using Informal Language. Technical report: CSI-R9516, December, Computing Science Institute, University of Nijmegen, Nijmegen, The Netherlands, 1995.

In this paper we study one aspect of the analysis of information systems, viz., how to obtain a (formal) model using informal formulations. We give a general framework for this modeling process, and also discuss the cognitive identity of domain experts. The starting point of the modeling process is a set of formulations (intended as an informal specification). Initially, these formulations need not form a complete and consistent specification. In an iterative process, alternating deduction and induction, an informal specification and corresponding formal model are to be derived. Rather than aiming at one (large) model, certain partial models are derived that collectively describe the application domain in a complete and consistent fashion. This process involves both domain expert and system analyst, communicating primarily in natural language.

This communication is supported by a system analyzing informal formulations to obtain fragments of the (formal) model, and paraphrasing fragments of this model to obtain feedback. This feedback mechanism is intended to support the validation of the model, regarding both structural aspects and constraints on populations.

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A.H.M. ter Hofstede, E. Lippe, and Th.P. van der Weide. A Categorical Framework for Conceptual Data Modeling: Definition, Application, and Implementation. Technical report: CSI-R9512, November, Computing Science Institute, University of Nijmegen, Nijmegen, The Netherlands, 1995.

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 the use of category theory for this purpose is addressed. Well­known conceptual data modeling concepts, such as relationship types, generalization, specialization, and collection types are discussed from a categorical point of view. An important advantage of this framework 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 set­based approaches to semantics. Applications of the framework in the context of schema transformations and improved automated modeling support are discussed.

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A.H.M. ter Hofstede, F.J.M. Bosman, and Th.P. van der Weide. Toward a Data Modeling Shell. Technical report, November, Computing Science Institute, University of Nijmegen, Nijmegen, The Netherlands, 1995.

Much research has been performed into improved automated modeling support. Ideally, a modeling support environment is highly flexible and allows analysts to define their own concepts and ways of working. While in general this seems an unattainable goal, for specific types of modeling techniques this might be achieved. In this paper, a data modeling shell is discussed which is based on a framework for conceptual data modeling techniques embedded in category theory. An important property of the framework is its ``configurablesemantics'', which means that features such as null values, uncertainty, and temporal behavior can be added by selecting appropriate instance categories. Hence, the data modeling shell not only allows syntactic conventions, including representational aspects, to be customized for a conceptual data modeling technique, it also allows a choice of required semantic features.

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J.W.G.M. Hubbers, and N.E. van Oosterom. Modellering van interactie tussen Wegverkeerssystemen: Opstellen van Modellen. Technical report: CSI-N9506, Computing Science Institute, University of Nijmegen, 1995, In Dutch.

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J.W.G.M. Hubbers, and N.E. van Oosterom. Modellering van interactie tussen Wegverkeerssystemen. Technical report: CSI-N9505, Computing Science Institute, University of Nijmegen, Nijmegen, The Netherlands, 1995, In Dutch.

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J.W.G.M. Hubbers, and N.E. van Oosterom. Modellering van interactie tussen Wegverkeerssystemen: Lezershandleiding. Technical report: CSI-N9507, Computing Science Institute, University of Nijmegen, Nijmegen, The Netherlands, 1995, In Dutch.

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T.W.C. Huibers, I. Ounis, and J.-P. Chevallet. Axiomatization of a Conceptual Graph Formalism for Information Retrieval in a Situated Framework. Technical report, July, Groupe MRIM of the Laboratoire de Génie Informatique, Grenoble, France, 1995.

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T.W.C. Huibers, and N. Denos. A Qualitative Ranking Method for Logical Information Retrieval Models. Technical report, August, Groupe MRIM of the Laboratoire de Génie Informatique, Grenoble, France, 1995.

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A.A.F. van der Maas, A.H.M. ter Hofstede, and P.F. de Vries Robbé. Toward formal patient case analysis: generic modelling of patient specific temporal knowledge. Technical report, March, Computing Science Institute, University of Nijmegen, The Netherlands, 1995.

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H.A. (Erik) Proper, and T.A. Halpin. Conceptual Schema Optimisation - Database Optimisation before sliding down the Waterfall. Technical report, July, Department of Computer Science, University of Queensland, Brisbane, Queensland, Australia, 1995.

In this article we discuss an approach to database optimisation in which a conceptual schema is optimised by applying a sequence of transformations. By performing these optimisations on the conceptual schema, a large part of the database optimisation can be done before actually sliding down the software development waterfall.

When optimising schemas, one would like to preserve some level of equivalence between the schemas before and after a transformation. We distinguish between two classes of equivalence, one based on the mathematical semantics of the conceptual schemas, and one on conceptual preference by humans.

As a medium for the schema transformations we use the universe of all (correct) conceptual schemas. A schema transformation process can then be seen as a journey (a schema- time worm) within this universe. The underlying theory is conveyed intuitively with sample transformations, and formalised within the framework of Object-Role Modelling. A metalanguage is introduced for the specification of transformations, and more importantly their semantics. While the discussion focusses on the data perspective, the approach has a high level of generality and is extensible to process and behaviour perspectives.

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P.G.H. Toonen, and P. van Bommel. Markov Chain Fundamentals for Data Schema Transformations. Technical report: CSI-R9505, Computing Science Institute, University of Nijmegen, Nijmegen, The Netherlands, 1995.

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A. Valente, and P. van Bommel. From KISS to Implementation: A Study of Problems, Solutions, and Open Issues. Technical report: CSI-N9509, Computing Science Institute, University of Nijmegen, Nijmegen, The Netherlands, 1995.

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E.S.C. van de Ven, P. van Bommel, P.J.M. Frederiks, and Th.P. van der Weide. Natural Language Properties and Information Systems. Technical report: CSI-N9608, Computing Science Institute, University of Nijmegen, 1995.

In this paper the concept of natural language is discussed from three perspectives: which properties does natural language have from a psychologic point of view, how are natural language sentences built, and what is their meaning? The paper serves as a basis for applying natural language in information systems engineering.

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