Uwe Hohenstein

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Nearly all query languages discussed recently for the Entity-Relationship (ER) model do not possess a formal semantics. Languages are often defined by means of examples only. The reason for this phenomenon is the essential gap between features of query languages and theoretical foundations like algebras and calculi. Known languages offer arithmetic(More)
Schema statements in OWL are interpreted quite differently from analogous statements in relational databases. If these statements are meant to be interpreted as integrity constraints (ICs), OWL's interpretation may seem confusing and/or inappropriate. Therefore, we propose an extension of OWL with ICs that captures the intuition behind ICs in relational(More)
In this paper, we motivate and present a data model for conceptual design of structural and behavioural aspects of databases. We follow an object centered design paradigm in the spirit of semantic data models. The speciication of structural aspects is divided into modelling of object structures and modelling of data types used for describing object(More)
<italic>After the successful first International Workshop on Engineering Federated Database Systems (EFDBS'97) in Barcelona in June 1997 [CEH<supscrpt>+</supscrpt> 97], the goal of this second workshop was to bring together researchers and practitioners interested in various issues in the development of federated information systems, whereby the scope has(More)