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.

Flat graphical, conceptual modeling techniques are widely accepted as visually effective ways in which to specify and communicate the conceptual data requirements of an information system. Conceptual schema diagrams provide modelers with a picture of the salient structures underlying the modeled universe of discourse, in a form that can readily be understood by and communicated to users, programmers and managers. When complexity and size of applications increase, however, the success of these techniques in terms of comprehensibility and communicability deteriorates rapidly.

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 system; 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 ma...

This article discusses two highly intertwined issues. Firstly, we discuss the lack of top-down abstraction mechanisms in data modelling techniques; i.e. abstraction techniques that are fully integrated into the modelling technique and methodology and not just a `post-modelling process' add on. Secondly, we are concerned with the integration of object-oriented modelling techniques and traditional data modelling techniques.

In an information system a key role is played by the underlying data schema. This article starts out from the view that the entire modelling process of an information system's data schema can be seen as a schema transformation process. A transformation process that starts out with an initial draft conceptual schema and ends with an internal database schema for some implementation platform. This allows us to describe the transformation process of a database design as an evolution of a schema through a universe of data schemas. Doing so, allows for a better understanding of the actual design process, countering the problem of `software development under the lamppost'. Even when the information system design is finalised, the data schema can evolve further due to changes in the requirements on the system. We present a universe of data schemas that allows us to describe the underlying data schemas at all stages of their development. This universe of data schemas is used as a case ...

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 an other 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. This is a result of the fact that collection types are populatable types and such types tend to complicate updates. In this paper it is shown how a new kind of constraint, the extensional uniqueness constraint, allows for an alternative treatment of collection types avoiding update problems. The formal definition of this constraint type is presented, other advantages of its introduction are discussed, and its consequences for, among others, identification schemes are elaborated. Keywords--- Conceptu...

In this paper we are concerned with the principles underlying the utility of modelling concepts, in particular in the context of architecture-modelling. Firstly, some basic concepts are discussed, in particular the relation between information, language, and modelling. Our primary area of application is the modelling of enterprise architectures and information system architectures, where the selection of concepts used to model di#erent aspects very much depends on the specific concerns that need to be addressed. The approach is illustrated by a brief review of the relevant aspects of two existing frameworks for modelling of (software intensive) information systems and their architectures.

Although the need for formalisation of modelling techniques is generally recognised, not much literature is devoted to the actual process involved. This is comparable to the situation in mathematics where focus is on proofs but not on the process of proving. This paper tries to accomodate for this lacuna and provides essential principles for the process of formalisation in the context of modelling techniques as well as a number of small but realistic formalisation case studies.

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.

. This paper analyses some useful enhancements required by datawarehouse systems. This concerns the conceptual modeling representation and visualisation, the query definition and optimization. A general framework is proposed to integrate terminological reasoning and a natural language interface in a flexible knowledge representation system in order to meet datawarehouse needs. INTRODUCTION Nowadays, database access is not exclusively reserved to computer scientists. Many people want to consult directly databases and exploit the data. For these reasons, datawarehouse concerns systems that try to give to nonspecialist end-users a simplified view of complex database. Such systems involve database abstraction, query formulation and result analysis. This notion is partially covered by some other business terms, like Enterprise Information System, Business Intelligence, Corporate Analysis System, Online Analytical Processing etc... Let us consider that Datawarehouse involves all the efforts...