The purpose of this paper is to show that logic provides a convenient formalism for studying classical database problems. There are two main parts to the paper, devoted respectively to conventional databases and deductive databases. In the first part, we focus on query languages, integrity modeling and maintenance, query optimization, and data

We review basic premises underlying the application of conceptual modelling to the development of information systems and point out a fundamental problem arising from the broad range of concepts that need to be modelled. We then argue that conventional conceptual models are weak for such broad domains of discourse because they come with built-in collections of primitive notions in terms of which conceptual modelling is to be done. Telos is then introduced as a conceptual modelling language designed for capturing knowledge about information systems and it is argued that, unlike its peers, it offers facilities not only for modelling an application but also the notions used to model an application. The presentation of features of the language is eclectic and generally non-technical. Details about Telos can be found in [Mylopoulos90] and [Koubarakis89].

Abstract. We introduce a distributed architecture to endow multi-agent systems with a social layer in which norms are explicitly represented and managed via rules. We propose a class of rules (called institutional rules) that operate on a database of facts (called institutional states) representing the state of affairs of a multi-agent system. We define the syntax and semantics of the institutional rules and describe a means to implement them as a logic program. We show how the institutional rules and states come together in a distributed architecture in which a team of administrative agents employ a tuple space (i.e., a kind of blackboard system) to guide the execution of a multi-agent system. 1

Part decomposition and, conversely, the construction of composite objects out of individual parts have long been recognized as ubiquitous and essential mechanisms involving abstraction. This applies, in particular, in areas such as CAD, manufacturing, software development, and computer graphics. Although the part-of relationship is distinguished in object-oriented modeling techniques, it ranks far behind the concept of generalization/specialization and a rigorous definition of its semantics is still missing. In this paper we first show in which ways a shift in emphasis on the part-of relationship leads to analysis and design models that are easier to understand and to maintain. We then investigate the properties of part-of relationships in order to define their semantics. This is achieved by means of a categorization of part-of relationships and by associating semantic constraints with individual categories. We further suggest a precise and, compared with existing techniques, less redundant specification of constraints accompanying part-of categories based on the degree of exclusiveness and dependence of parts on composite objects. Although the approach appears generally applicable, the object-oriented Unified Modeling Language (UML) is used to present our findings. Several examples demonstrate the applicability of the categories introduced.

IN THIS thesis, a new methodology is presented which supports the efficient representation, indexing and retrieval of images by content. Images may be indexed and accessed based on spatial relationships between objects, properties of individual objects, and properties of object classes. In particular, images are first decomposed into groups of objects, called "image subsets", and are indexed by computing addresses to all such groups. All groups up to a predefined maximum size are considered. This methodology supports the efficient processing of queries by image example and avoids exhaustive searching through the entire image database.

Abstract. Norms constitute a powerful coordination mechanism among heterogeneous agents. In this paper, we propose a rule language to specify and explicitly manage the normative positions of agents (permissions, prohibitions and obligations), with which distinct deontic notions and their relationships can be captured. Our rule-based formalism includes constraints for more expressiveness and precision and allows to supplement (and implement) electronic institutions with norms. We also show how some normative aspects are given computational interpretation. 1

Agent-based architectures are an effective method for constructing open, dynamic, distributed information systems. The KRAFT system exploits such an architecture, focusing on the exchange of information -- in the form of constraints and data -- among participating agents. The KRAFT approach is particularly wellsuited to solving design and configuration problems, in which constraints and data are retrieved from agents representing customers and vendors on an extranet network, transformed to a common ontology, and processed by mediator agents. This paper describes the KRAFT system, discusses the issues involved in joining a KRAFT network from the point-of-view of information providers in Cyberspace, and examines the role of autonomous and mobile agents in KRAFT.

Norms are widely recognised as a means of coordinating multi-agent systems. The distributed management of norms is a challenging issue and we observe a lack of truly distributed computational realisations of normative models. In order to regulate the behaviour of autonomous agents that take part in multiple, related activities, we propose a normative model, the Normative Structure (NS), an artifact that is based on the propagation of normative positions (obligations, prohibitions, permissions), as consequences of agents’ actions. Within a NS, conflicts may arise due to the dynamic nature of the MAS and the concurrency of agents ’ actions. However, ensuring conflict-freedom of a NS at design time is computationally intractable. We show this by formalising the notion of conflict, providing a mapping of NSs into Coloured Petri Nets and borrowing well-known theoretical results from that field. Since online conflict resolution is required, we present a tractable algorithm to be employed distributedly. We then demonstrate that this algorithm is paramount for the distributed enactment of a NS.

Introduction New techniques are sorely needed to aid in the development and maintenance of large application systems. The problem with traditional approaches to software engineering is well in evidence in the field of o#ce information systems: it is costly and di#cult to extend existing applications, and to get unrelated applications to "talk" to each other. The objectoriented approach is already being tentatively applied in the modeling of "o#ce objects" and in the presentation of these entities to users as such in "desktop" interfaces to o#ce software. In order to fully exploit the approach to achieve integrated o#ce systems, we need to use object-oriented programming languages, object-oriented run-time support, and object-oriented software engineering environments. We can view the fundamental idea behind the object-oriented approach as that of encapsulation: object-oriented languages and systems exploit encapsulation in various ways in an attempt to enhance productivity through, f

Evaluating and comparing modelling languages is a prerequisite for progress in the field of conceptual modelling. However, only little research has been dedicated to the investigation of appropriate evaluation methods. It is common practice that mainly those who design modelling language decide about the relevance of particular features. In this paper, we argue that such an approach does not satisfy common academic standards. The quality of a modelling language depends on a variety of tasks and potential users, some of which are beyond the scope of language designers. Therefore, the evaluation of modelling languages requires a cross-disciplinary approach. Furthermore, it has to be taken into account that the analysis of a language imposes severe epistemological problems. Against this background, we introduce a meta-framework for the evaluation of modelling languages. It includes a conceptual model to guide and structure multi-perspective evaluations.