2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993 1992 1991 1990 1989 1988 1987 1985 1984 1982 1980 1979 1978 1977 1976 1975
Journals Conferences Reports
Bommel, P. van and Lucasius, C.B. and Weide, Th.P. van der, Genetic Algorithms for Optimal Logical Database Design. Information and Software Technology, Nr: 12, Vol: 36, Pages: 725-732, 1994
The focus of this paper is database design using automated database design tools or more general CASE tools. We present a genetic algorithm for the optimization of (internal) database structures, using a multi-criterion objective function. This function expresses conflicting objectives, reflecting the well-known time/space trade-off. This paper shows how the solution space of the algorithm can be set up in the form of tree structures (forests), and how these are encoded by a simple integer assignation. Genetic operators (database transformations) defined in terms of this encoding behave as if they manipulate tree structures. Some basic experimental results produced by a research prototype are presented.
[ cite ]
Kwaaitaal, I. and Hoogeveen, M. and Weide, Th.P. van der, A reference model for the impact of standardization on multimedia database management systems. Computer Standards and Interfaces, Vol: 16, Pages: 45-54, 1994
This article discusses the standardization of MDBMSs which is needed to keep pace with rapid developments in the area of multimedia systems. A reference model for the impact of standardization on MDBMSs is presented which summarises the result of a survey of relevant standards. The reference model is used to identify standardization gaps. Currently, one of the most important gaps is the lack of a standard multimedia database language for definition and manipulation of multimedia data.
[ cite ]
Proper, H.A. and Weide, Th.P. van der, EVORM - A Conceptual Modelling Technique for Evolving Application Domains. Data & Knowledge Engineering, Vol: 12, Pages: 313-359, 1994
In this paper we present EVORM, a data modelling technique for evolving application domains. EVORM is the result of applying a general theory for the evolution of application domains to the object role modelling technique PSM, a generalisation of ER, EER, FORM and NIAM.
First the general theory is presented. This theory describes a general approach to the evolution of application domains, abstracting from details of specific modelling techniques. This theory makes a distinction between the underlying information structure and 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.
After a (short) introduction to PSM, this general theory is applied, resulting in EVORM. Besides having a right of its own, the usefulness of the general theory is demonstrated by interpreting its abstract results, resulting in more intuitive rules for EVORM.
Journals Conferences Reports
Bommel, P. van and Lucasius, C.B. and Weide, Th.P. van der, Pool Heuristics in Evolutionary Database Optimization. Proceedings of the International Conference on Information Systems and Management of Data (CISMOD 94), Edited by: N. Prakash. Pages: 76-90, October, 1994
This paper describes several new results of the project C2I at the University of Nijmegen, The Netherlands. The focus of C2I is the transformation of data models from the conceptual to the internal level. Several aspects are involved, such as data structures, operations, populations (values) and integrity constraints. Special emphasis is given to optimization of data structures with respect to the trade-off between response time and storage space.
New results include PHSL, an abstract Pool Heuristic Specification Language for expressing the basic actions in advanced (evolutionary) optimization strategies. Furthermore, the applicability of the approach to traditional Codasyl network models is illustrated (it has already been shown that the approach is applicable to relational and nested-relational models).
[ cite ]
Burgers, C.A.J. and Proper, H.A. and Weide, Th.P. van der, An Information System organized as Stratified Hypermedia. CISMOD94, International Conference on Information Systems and Management of Data, Edited by: N. Prakash. Pages: 159-183, October, 1994
In this paper we investigate the relation between modern hypertext approaches and conventional data modelling techniques, such as PSM. We show how query formulation in a traditional information system can be regarded as a stratified hypermedia featuring two levels of abstraction. The first level of abstraction covers the structure of the stored information, and the second level the information itself.
The investigations provide us with the mechanism of query by navigation as a novel avenue for improved query formulation in information systems.
[ cite ]
Hofstede, A.H.M. ter and Proper, H.A. and Weide, Th.P. van der, Supporting Information Disclosure in an Evolving Environment. Proceedings of the 5th International Conference DEXA`94 on Database and Expert Systems Applications, Athens, Greece, EU, Edited by: D. Karagiannis. Lecture Notes in Computer Science, Vol: 856, Pages: 433-444, September, Springer, 1994, ISBN 3540584358
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.
[ cite ]
Hofstede, A.H.M. ter and Weide, Th.P. van der, Fact Orientation in Complex Object Role Modelling Techniques. Proceedings of the First International Conference on Object-Role Modelling (ORM-1), Edited by: T.A. Halpin, and R. Meersman. Pages: 45-59, July, 1994
A number of proposals have been made to extend conventional data modelling techniques with concepts for modelling complex object structures, such as power types, sequence types and schema types. A drawback of the introduction of such new concepts is that the original simplicity of a single populatable concept is lost. In this paper we will show how a new kind of constraint, the extensional uniqueness constraint, can overcome this problem. Another advantage of this constraint is that it enables a less rigid identification schema. The usefulness of this new constraint is demonstrated in some concrete modelling situations.
[ cite ]
Hofstede, A.H.M. ter and Proper, H.A. and Weide, Th.P. van der, A Conceptual Language for the Description and Manipulation of Complex Information Models. Seventeenth Annual Computer Science Conference, Edited by: G. Gupta. Australian Computer Science Communications, Vol: 16, Pages: 157-167, January, University of Canterbury, Christchurch, New Zealand, 1994, ISBN 047302313
Conceptual data modelling techniques aim at the representation of data (structures) at a high level of abstraction. This implies that conceptual data modelling techniques should not only be capable of representing complex structures in a natural way, but also the rules (constraints) that must hold for these structures. Contemporary data modelling techniques, however, do not provide a language which, on the one hand, has a formal semantics and, on the other hand, leads to natural looking expressions. In this paper, an informal introduction to such a language (LISA-D) for the data modelling technique (PSM), is presented. PSM is a generalisation of object-role models (such as ER, NIAM and FORM).
Journals Conferences Reports
Hofstede, A.H.M. ter and Proper, H.A. and Weide, Th.P. van der, Grammar Based Information modelling. Technical Report CSI-R9414, University of Nijmegen
In this paper information modelling is considered as a process leading to a grammar that describes the communication of an information system with its users. This grammar (the information grammar) should approximate as close as possible the language spoken in the problem domain (the expert language). The information grammar is centered around the information structure and concretized by names for the elements of the information structure, while LISA-D is the framework for the information grammar. The semantics of LISA-D is expressed in terms of path expressions, a (for this purpose) convenient variant of relational algebra.
As it is important that queries can be formulated in a way close to the perception of users, LISA-D exploits the naturla language approach of NIAM (of which PSM is an extension). Queries in LISA-D can be formulated in terms used in the application domain involved. This, of course, is an important prerequisite for achieving succesfull query formulation support. Finally, the concept of query by navigation and query by construction are introduced as mechanisms to support query formulation.
Proper, H.A. and Weide, Th.P. van der, A General Theory for the Evolution of Application Models - Full version. Technical report, Department of Computer Science, University of Queensland, Brisbane, Australia, 1994
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.
[ cite ]