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.

Relational query languages such as SQL and QBE are less than ideal for end user queries since they require users to work explicitly with structures at the relational level, rather than at the conceptual level where they naturally communicate. ConQuer is a new conceptual query language that allows users to formulate queries naturally in terms of

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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.

Formulating non-trivial queries in relational languages such as SQL and QBE can prove daunting to end users. ConQuer is a conceptual query language that allows users to formulate queries naturally in terms of elementary relationships, operators such as “and”, “or”, “not ” and “maybe”, contextual for-clauses and object-correlation, thus avoiding the need to deal explicitly with implementation details such as relational tables, null values, outer joins, group-by clauses and correlated subqueries. While most conceptual query languages are based on the Entity-Relationship approach, ConQuer is based on Object-Role Modeling (ORM), which exposes semantic domains as conceptual object types, allowing queries to be formulated via paths through the information space. As a result of experience with the first implementation of ConQuer, the language has been substantially revised and extended to become ConQuer–II, and a new tool, ActiveQuery, has been developed with an improved interface. ConQuer-II’s new features such as arbitrary correlation and subtyping enable it to be used for a wide range of advanced conceptual queries. Introduction and Related Work

This paper was presented at OOER'95: 14 th International Conference on Conceptual Modeling, Springer LNCS, vol. 1021, pp. 191-203, and is reproduced here by permission

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...

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.

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 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,...