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Journals Conferences
Falkenberg, E.D. and Pols, R. van der and Weide, Th.P. van der, Understanding process structure diagrams. Information Systems, Nr: 4, Vol: 16, Pages: 417-428, September, 1991
This paper is an attempt to sketch a framework for understanding process structure diagrams, as used for business process analysis, being one phase of information system design. Proper understanding of any description method can only be achieved by specifying all the concepts (objects, predicates) and axioms of this method in a precise, formal way. On this basis, different description methods can be properly compared, translated, and thus their similarities and/or differences better understood. In our paper, this approach is applied to two description methods for process structuring, Dataflow Diagrams and Activity Graphs.
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Bommel, P. van and Hofstede, A.H.M. ter and Weide, Th.P. van der, Semantics and verification of object-role models. Information Systems, Nr: 5, Vol: 16, Pages: 471-495, October, 1991
In this paper we formalise data models that are based on the concept of predicator, the combination of an object type and a role. A very simple model, the Predicator Model, is introduced in a rigid formal way.
We introduce the concept of population as an instantiation of an information structure. A primitive manipulation language is defined in the style of Relational Algebra. Well-known types of constraints are defined in terms of the algebra introduced, as restrictions on populations. They are given more expressive power than is usually the case.
Constraints are of central importance for identification purposes. Weak identification ensures identifiability of objects within a specific population, while structural identification ensures identifiability of objects within every population.
Different levels of constraint inconsistency are defined and it is shown that the verification of two important levels is NP-complete.
Bruza, P.D. and Weide, Th.P. van der, The Modelling and Retrieval of Documents using Index Expressions. ACM SIGIR FORUM (Refereed Section), Nr: 2, Vol: 25, 1991
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.
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Journals Conferences
Bommel, P. van and Weide, Th.P. van der, Towards Database Optimization by Evolution. Proceedings of the Computing Science in the Netherlands Conference (CSN91), Edited by: A.J. van de Goor. Pages: 109-123, November, 1991
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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Bruza, P.D. and Weide, Th.P. van der, Deducing Relevant Information using the Information Disclosure Machine. Proceedings of the Computing Science in the Netherlands Conference (CSN91), Edited by: A.J. van de Goor. Pages: 135-149, November, 1991
In this paper we consider information disclosure as a deductive process. We introduce the Disclosure Machine as a paradigm for matching user queries with characterizations of information objects. The Disclosure Machine is based on the following corner stones: logical inference for proving relevancy, plausible inference for computing relevance and proximity for balancing relevance according to object coherence (Hypertext). Next we discuss the limitations of stateoftheart approaches, and suggest the Hyperindex Machine as an improved mechanism. This machine is based on the concept of index expressions. Such expressions provide a more complete characterization mechanism for objects.
Spiegel, P.L. van der and Driessen, J.T.W. and Bruza, P.D. and Weide, Th.P. van der, A Transaction Model for Hypertext. Proceedings of the Data Base and Expert System Applications Conference (DEXA 91), Berlin, Germany, EU, Edited by: D. Karagiannis. Pages: 281-286, Springer, 1991
This paper presents a specification of Hypertext systems on several levels of abstraction, and describes translations between these different levels. The Hypertext system will be organised according to a stratified architecture, which is a generalisation of the so-called Two Level Architecture. We describe a user interface for the Hypertext system, examine the user's elementary operations (transactions) and present the correspo nding user view on the system. Next a conceptual schema is presented, that describes Hypertext from the perspective of the author (editor) of the information. We describe the user transactions in terms of operations on the conceptual schema. An object oriented implementation of this Hypertext system is presented. We show how the object hierarchy is derived from the conceptual schema.
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