This paper describes the main concepts behind the implementation of the Merlin prototype and sketches current and further work within the research project evolving from the current experience with the prototype.

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.

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 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

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. keywords: Evolving Information System, Conceptual Query Language EVORM ER, PSM, Elisa-D 1 Introduction Flexible behaviour of an organisation may entail a rapidly changing info...

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. 1 Introduction In the last decades, a plethora of modelling techniques for the design of information systems has been developed (see e.g. [Bub86]). In general, these modelling techniques provide only a crude and incomplete description of their syntax, and semantics ([HW92]). This situation has led to the Methodology...

. In this paper a conceptually simple structural object model focusing on object types, attributes and ISA relationships is introduced. The model is derived mainly from an extended Entity-Relationship approach, but concepts from other semantic and object-oriented models have influenced its features. It is shown how high-level conceptual data models can be mapped to this model, and to what extent the object model subsumes classical modeling paradigms. 1 Introduction In recent years numerous data models for the conceptual modeling of information systems have been proposed. Among them there are semantic data models like SDM [13], IFO [3] and (extended) ER models [8, 9, 10, 24, 31, 34], complex object models like [1, 18, 26], purely object-based models like FDM [28] as well as object-based models with complex values such as [22]. All the approaches have different motivation, terminology, and aims. Here we aim to show you how some of these models can be translated into a conceptually simpl...

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...

For succesful information systems development, conceptual data modelling is essential. Nowadays many techniques for conceptual data modelling exist, examples are NIAM, FORM, PSM, many (E)ER variants, IFO, and FDM. In-depth comparisons of concepts of these techniques is very difficult as the mathematical formalisations of these techniques, if existing at all, are very different. 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. Well-known conceptual data modelling concepts are discussed from a category theoretic point of view. Advantages and disadvantages of the approach chosen will be outlined. Keywords: Conceptual Data Modelling, Category Theory, Meta Modelling Classification: 68P99 (AMS-1991), H.1.0. (CR-1991) 1 Introduction It seems an undisputed fact that, opposed to most mature scientific disciplines, the discipline of information systems does not hav...

The challenge companies will have to meet when making the leap from the industrial era to the knowledge era is the memorization of corporate knowledge and its dissemination to employees throughout the organization. Developing a corporate memory is the means chosen by DMR Consulting Group to capitalize on and manage its expertise in information technology. This paper presents a study conducted to choose a formalism to represent the know-how and methodologies # processes, techniques and learning materials # in corporate memory. It compares modeling formalisms against speci#c requirements and demonstrates that conceptual graphs are well suited to implement corporate memories. More speci#- cally,we show that conceptual graphs support: #i# classi#cation and partial knowledge, #ii# category or instance in relationship and #iii# category or instance in metamodel. 1 Introduction Nowadays there is consensus on the value of corporate knowledge. The knowledge is at the center; an em...