IRIS Research Publications


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Journal

A.H.M. ter Hofstede, and Th.P. van der Weide. Formalisation of techniques: chopping down the methodology jungle. In: Information and Software Technology, Nr: 1, Vol: 34, Pages: 57-65, January, 1992.

In this article we discuss formalisation of techniques in the context of Information System Development methodologies. When such methodologies are developed, the primary goal is applicability. After the methodology has proven itself in practice, the methodology will be applied in more sophisticated situations, pushing the methodology to its limits. in those cases, informal definitions are known to be inappropriate. We will go into some typical problems. After that, we describe a procedure for proper formalisation. The Predicator Model is presented as an extended example. Finally, we describe some experiences with this approach to formalisation.

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Th.P. van der Weide, A.H.M. ter Hofstede, and P. van Bommel. Uniquest: Determining the Semantics of Complex Uniqueness Constraints. In: The Computer Journal, Nr: 2, Vol: 35, Pages: 148-156, April, 1992.

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 encouter complex uniqueness constraints, that are missed easily. The Uniquest Algorithm provides a handle for recognition.

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P. van Bommel, and Th.P. van der Weide. Reducing the search space for conceptual schema transformation. In: Data & Knowledge Engineering, Vol: 8, Pages: 269-292, 1992.

In this paper we focus on the transformation of a conceptual schema into an internal schema. For a given conceptual schema, quite a number of internal schemata can be derived. This number can be reduced by imposing restrictions on internal schemata. We present a transformation algorithm that can generate internal schemata of several types (including the relational model and the NF2 model). Guidance parameters are used to impose further restrictions. We harmonise the different types of schemata by extending the conceptual language, such that both the conceptual and the internal models can be represented within the same language.

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P.D. Bruza, and Th.P. van der Weide. Stratified Hypermedia Structures for Information Disclosure. In: The Computer Journal, Nr: 3, Vol: 35, Pages: 208-220, 1992.

In this paper we generalize the two level approach 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 to how the underlying information model is layered. Two layers are featured: the hyperbase and the hyperindex. A characterization calculus is presented for the characterization of structured elements. This calculus forms the basis of a logic­based approach in connection with the associated information processor (Disclosure Machine). The logic­based 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.

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M.-J. Nederhof, and J.J. Sarbo. Partial Evaluation Grammars. In: Computer Languages, Nr: 2, Vol: 18, Pages: 137-151, 1992.

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Conference

P. van Bommel, and Th.P. van der Weide. Towards Database Optimization by Evolution. In: Proceedings of the International Conference on Information Systems and Management of Data (CISMOD 92), Edited by: A.K. Majumdar, and N. Prakash. Pages: 273-287, July, 1992.

In this paper we focus on optimization of database schema transformation, by evolutionary (or genetic) search. A framework for transforming conceptual data schemata into efficient internal schemata is presented. We consider this problem from the viewpoint of searching through the space of all correct, but possibly incomplete internal representations of the conceptual schema at hand. A search strategy is established, based on the use of evolutionary operators. The relevant evolutionary operators are introduced.

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A.H.M. ter Hofstede, T.F. Verhoef, E.R. Nieuwland, and G.M. Wijers. Specification of Graphic Conventions in Methods. In: Proceedings of the Third Workshop on the Next Generation of CASE Tools, Edited by: B. Theodoulidis, and A.G. Sutcliffe. Pages: 185-215, May, 1992.

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A.H.M. ter Hofstede, T.F. Verhoef, E.R. Nieuwland, and G.M. Wijers. Integrated Specification of Method and Graphic Knowledge. In: Proceedings of the Fourth International Conference on Software Engineering and Knowledge Engineering, Capri, Italy, EU, Pages: 307-316, June, IEEE, Los Alamitos, California, USA, 1992.

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G.M. Wijers, A.H.M. ter Hofstede, and N.E. van Oosterom. Representation of Information Modelling Knowledge. In: Next Generation CASE Tools, Edited by: V.-P. Tahvanainen, and K. Lyytinen. Studies in Computer and Communication Systems, Vol: 3, Pages: 167-223, IOS Press, Amsterdam, The Netherlands, EU, 1992.

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E.D. Falkenberg, J.L.H. Oei, and H.A. (Erik) Proper. A Conceptual Framework for Evolving Information Systems. In: Dynamic Modelling of Information Systems II, Amsterdam, The Netherlands, EU, Edited by: H.G. Sol, and R.L. Crosslin. Pages: 353-375, North-Holland, Amsterdam, The Netherlands, EU, 1992, ISBN 0444894055.

In this paper, we will treat evolving information systems, which support the information needs of an evolving organization. Such a system is able to change at the same pace as the organization does, such that there is no need to interrupt the activities of the organization. Such a system supports changes of all time- and application-dependent aspects.

We will present a conceptual framework of an approach to evolving information systems. The architecture of such a system will be explained, where we will make disctinctions between meta model and application model, and between world, action and behavioural aspects of these models.

Furthermore, evolution management of application models will be discussed, whereby update is regarded as recording, correction or forgetting, and whereby state transitions are considered on three different levels, viz. the organizational level, the recording level and the correction level. A formal specification of this approach to evolution management will be provided too.

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E.D. Falkenberg, J.L.H. Oei, and H.A. (Erik) Proper. Evolving Information Systems: Beyond Temporal Information Systems. In: Proceedings of the Data Base and Expert System Applications Conference (DEXA`92), Valencia, Spain, EU, Edited by: A.M. Tjoa, and I. Ramos. Pages: 282-287, September, Springer, 1992, ISBN 3211824006.

Nowadays, in order for an organisation to be competitive, it must be able to adapt quickly to its dynamic environment. In this paper, we discuss the need for information systems which are capable to evolve to the same extent as organisations do. Requirements of evolving organisations on their information systems are identified, followed by alternative approaches to adequate information systems development life cycles. We adopt an evolutionary approach resulting in so-called evolving information systems.

On the basis of requirements and an architecture for these evolving information systems, the distinction from traditional information systems is explained. Traditional information systems, including temporal information systems, appear to be degenerations of our evolving information systems. A conceptual framework for update in evolving information systems is derived from the requirements. An event level, a recording level and a correction level are distinguished in this framework for update.

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A.H.M. ter Hofstede, H.A. (Erik) Proper, and Th.P. van der Weide. Data Modelling in Complex Application Domains. In: Proceedings of the Fourth International Conference CAiSE`92 on Advanced Information Systems Engineering, Manchester, United Kingdom, EU, Edited by: P. Loucopoulos. Lecture Notes in Computer Science, Vol: 593, Pages: 364-377, May, Springer, 1992, ISBN 3540554815.

In many non trivial application domains, object types with a complex structure occur. Data modelling techniques which only allow flat structures are not suitable for representing such complex object types. In this paper a general data modelling technique, the Predicator Set Model, is introduced, which is capable of representing complex structures in a natural way.

The expressiveness of the Predicator Set Model is illustrated by means of a number of examples. In those examples, the Predicator Set Model's expressiveness is related to the expressiveness of more traditional modelling techniques. Furthermore, some notational conventions are defined, which enable a more compact representation of complex structures.

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Reports

J.L.H. Oei, H.A. (Erik) Proper, and E.D. Falkenberg. Modelling the Evolution of Information Systems. Technical report: CSI-R9236, Department of Information Systems, University of Nijmegen, Nijmegen, The Netherlands, EU, 1992.

In this article, we discuss the need for information systems capable of evolving to the same extent as organisation systems do. A set of requirements for evolving information systems is presented, implying the importance of the time concept in these systems. On the basis of these requirements an architecture and a conceptual framework for evolving information systems is proposed.

In our conceptual framework for update we distinguish recording, correction and forgetting. State transitions are considered on three different levels of abstraction, viz. the event level, the recording level and the correction level. A formal specification of the transformation process between user update requests, primitive update requests, and the three-level model for update is provided.

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E.D. Falkenberg, J.L.H. Oei, and H.A. (Erik) Proper. A Metamodel for Update in Information Systems. Technical report, Department of Information Systems, University of Nijmegen, Nijmegen, The Netherlands, EU, 1992.

An evolving information system supports the information needs of an evolving organisation. These systems are able to adapt themselves instantaneously to the changes of the supported organisation, such that there is no need to interrupt the activities of the organisation. Furthermore, evolving information systems support changes of all time- and application-dependent aspects, such as the database and the schema of the application.

The main focus of this paper is on update in evolving information systems. A framework for the processing of updates in evolving information systems is presented. In this framework, update is regarded as recording, correction or forgetting, and state transitions are considered on three different levels of abstraction, viz. the event level, the recording level and the correction level. A formal specification of this framework is provided as well. Furthermore, the notion of evolution dependency is discussed, taking the dependencies of changes within the universe of discourse into consideration.

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F.A. Grootjen. Efficient recursive backup parsing. University of Nijmegen, 1992.

There are several ways to create an exact recognizer for the language defined by a context free grammar. The recursive backup technique, proposed by, is capable of handling (locally) ambiguous gram-mars. Due to its structure, it is not limited to context free grammars, but applicable for affix grammars in general. This paper shows that 'tactful' recursive backup parsing can be efficient, in spite of its worst case exponential time complexity. This 'tact' however, should not be supplied by the grammar writer, but automatically deduced by a parser generator. In this paper we will discuss the deduction process for a simple form of two-level grammars: Affix Grammars over Finite Lattices (AGFLs), a formalism to express the syntax of natural languages.

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T.A. Halpin, and J.L.H. Oei. A Framework for Comparing Conceptual Modelling Languages. Technical report: CSI-R9229, Department of Information Systems, University of Nijmegen, Nijmegen, The Netherlands, 1992.

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A.H.M. ter Hofstede, H.A. (Erik) Proper, and Th.P. van der Weide. A Note on Schema Equivalence. Technical report: CSI-R9230, Department of Information Systems, University of Nijmegen, Nijmegen, The Netherlands, EU, 1992.

In this paper we introduce some terminology for comparing the expressiveness of conceptual data modelling techniques, such as ER, NIAM, and PM, that are finitely bounded by their underlying domains. Next we consider schema equivalence and discuss the effects of the sizes of the underlying domains. This leads to the introduction of the concept of finite equivalence. We give some examples of finite equivalence and inequivalence in the context of PM.

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J.L.H. Oei, L.J.G.T. van Hemmen, E.D. Falkenberg, and S. Brinkkemper. The Meta Model Hierarchy: A Framework for Information System Concepts and Techniques. Technical report, Department of Information Systems, University of Nijmegen, Nijmegen, The Netherlands, 1992.

The numerous information systems design methods and specification techniques being proposed, can be compared on the basis of different criteria. In this paper a framework for ordering information systems modelling techniques based on meta models is proposed. This framework, called the Meta Model Hierarchy, positions each technique according to an analysis of the distinctions between the basic concepts, and the set of constraints defined on these concepts.

Relations between meta models are distinguished: partitioning, restriction, and degeneration. Each modelling technique is then positioned in the Meta Model Hierarchy according to these order relations. The positioning of Entity-Relationship Modelling, NIAM and Petri-nets in the Meta Model Hierarchy is discussed as an illustration of the use of the approach.

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N.E. van Oosterom, and A.H.M. ter Hofstede. Towards the Implementation of Integrated NIAM and ExSpect: Generation of ExSpect Type Definitions from NIAM Schemas based on a Common Repository. Technical report, May, ITI-TNO, Delft, The Netherlands, EU, 1992, ESPRIT II Project PROOFS.

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Professional

A.H.M. ter Hofstede, T.F. Verhoef, E.R. Nieuwland, and G.M. Wijers. Application Development Workbench. In: DB/M, Nr: 4, Vol: 3, Pages: 50-52, July, 1992, In Dutch.

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A.H.M. ter Hofstede, T.F. Verhoef, N.E. van Oosterom, E.R. Nieuwland, and G.M. Wijers. BACHMAN Product Set: een solide ontwikkelomgeving. In: DB/M, Nr: 5, Vol: 3, Pages: 53-58, September, 1992, In Dutch.

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A.H.M. ter Hofstede, T.F. Verhoef, E.R. Nieuwland, and G.M. Wijers. Foundation: veelomvattend maar niet altijd overzichtelijk. In: DB/M, Nr: 1, Vol: 3, Pages: 15-17, January, 1992, In Dutch.

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A.H.M. ter Hofstede, T.F. Verhoef, E.R. Nieuwland, and G.M. Wijers. Oracle*CASE: nadruk op integratie en verificatie. In: DB/M, Nr: 3, Vol: 3, Pages: 38-41, May, 1992, In Dutch.

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A.H.M. ter Hofstede, H.A. (Erik) Proper, and Th.P. van der Weide. PSM: Datamodelleren in het Kwadraat. In: DB/Magazine, Nr: 4, Vol: 3, Pages: 37-41, June, 1992, In Dutch.

De huidige generatie van modelleringstechnieken schieten tekort voor het modelleren van complexe applicatiedomeinen. Voorbeelden van zulke applicatiedomeinen zijn: hypermedia-toepassingen, CAD/CAM systemen, en meta-modellering. Er is een stijgende behoefte aan modelleringstechnieken die het modelleren van dergelijke applicatiedomeinen ondersteunen.

In dit artikel presenteren we PSM, een exponent van een nieuwe generatie van datamodelleringstechnieken, welke geschikt is voor het modelleren van complexe gegevensstructuren.

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