The advent of graphical workstations lead to a new generation of interaction tools in database systems, where the use of graphics greatly enhances the quality of the interaction. Yet, Visual Query Languages (VQLs) present some limitations, deriving partly from their own paradigm and partly from the available technology. One of the basic drawbacks is the lack of formalization, in contrast to the wellestablished traditional languages. In this paper we propose a theoretical framework for visual interaction with databases, having a particular kind of hypergraph, the Structure Modeling Hypergraph (SMH), as a representation tool, able to capture the features of existing data models. SMHs profit from the basic property of diagrams while overcoming their limitations. Notable characteristics of SMHs are: uniform and unified representation of intensional and extensional aspects of databases, direct representation of containment relationships, and immediate applicability of direct manipulation p...

In this paper, we introduce a new hierarchical graph model to structure large graphs into small components by distributing the nodes (and edges likewise) into a hierarchy of packages. In contrast to other known approaches, we do not fix the type of underlying graphs. Moreover, our model is equipped with a rule-based transformation concept such that hierarchical graphs cannot only be used for static representation of complex system states, but also for the description of the dynamic system behaviour.

Abstract. This paper introduces an extension to the hypergraph data model used in the AutoMed data intergration approach that allows constraints common in static data modelling languages to be represented by a small set of primitive constraint operators. A set of equivalence rules are defined for this set of primitive constraint operators, and demonstrated to allow a mapping between relational, ER or UML models to be defined. The approach provides both a precise framework in which to compare data modelling languages, and forms the platform for further work in automating the process of transforming between different data modelling languages. 1

This paper illustrates how the diagram programming language DIAPLAN can be used to program visual systems. DIAPLAN is a visual rule-based language that is founded on the computational model of graph transformation. The language supports object-oriented programming since its graphs are hierarchically structured. Typing allows the shape of these graphs to be specified recursively in order to increase program security. Thanks to its genericity, DIAPLAN allows to implement systems that represent and manipulate data in arbitrary diagram notations. The environment for the language exploits the diagram editor generator DIAGEN for providing genericity, and for implementing its user interface and type checker.

Abstract. This paper presents a graph-based spatial model which can serve as a reference for guiding pedestrians inside buildings. We describe a systematic approach to construct the model from geometric data. In excess of the well-known topological relations, the model accounts for two important aspects of pedestrian navigation: firstly, visibility within spatial areas and, secondly, generating route descriptions. An algorithm is proposed which partitions spatial regions according to visibility criteria. It can handle simple polygons as encountered in floor plans. The model is structured hierarchically- each of its elements corresponds to a certain domain concept (‘room’, ‘door’, ‘floor ’ etc.) and can be annotated with meta information. This is useful for applications in which such information have to be evaluated. 1 Introduction and Related Work Pedestrian guidance within buildings [6] differs from customary navigation based on networks. This is due to the following reasons:

This report presents the Prometheus database model. The model is designed to satisfy the requirements expressed in a previous document [RKB99]. The new model is based on a graph model and is extended with some mechanisms existing in other models (e.g. the differentiation between association and aggregation) and some new mechanisms not found anywhere (e.g. synonymy at all levels). 1.

: Taxonomists classify the organisms they study in order to refer to, identify and understand them. However, the same organism may at times be classified according to different taxonomic opinions and subsequently have several alternative names or be placed in different taxa. As alternative classifications multiply, biologists are commonly faced with the need to compare and contrast taxonomies in order to identify how they differ in their organisation. Thus there is a pressing need for computer systems that are capable of handling multiple taxonomies arising from the combination of legacy data, newly described taxa, modern revisions and conflicting opinions. Many database systems have been built to handle taxonomic data. We review taxonomic databases and show that they do not provide taxonomists with the necessary tools to support their work. A new model of taxonomy (the Prometheus Model) is defined in [PK99] 1 , and we now compare existing database technology to our requirements and ...

Introduction Taxonomists in the Royal Botanic Garden, Edinburgh, specialise in the classification of flora from around the world. The classification of flora is a complex task involving historical records, literature references and specimens collected from the field. Using this information the taxonomists formulate classifications which are continually under review and vary between taxonomists. Currently the taxonomists at RGBE use an application called Pandora, which has been developed using a relational database [PP94], to manage their classification information; however the system is limited in the support required to model and manage this type of information. A review of current systems (e.g. [Pan93] [WAW93] [BPB93] [SLPS95]) showed that most of them are not built with the purpose of storing multiple-overlapping (and possibly contradictory) classifications, and the few that try do not offer a suitable environment for taxonomic work [RBK99a]. Object oriented databases are s

Multimedia presentation graphs are acyclic graphs with directed edges (DAG) used for visual specification of multimedia presentations. In this paper, we introduce two approaches in querying and manipulating multimedia presentation graphs. As our first approach, we present a modal calculus, called GCalculus (Graph Calculus), which has a second order syntax and first order semantics. The first order semantics in GCalculus provides a formal foundation for an implementation while the second order syntax allows us to specify paths of a graph and query relationships among objects that are encapsulated in the nodes of presentation graphs. In our second approach, we present a graph data model that allows explicit representation of graphs by partitioning object classes into simple classes, link classes, path classes, and graph classes. An extension of OQL for graphs and sequences, GOQL is presented as an alternative query language. Besides being attractive for standard database applications, ...

Abstract. The Semantic Link Network model SLN and Resource Space Model RSM are semantic models proposed separately for effectively specifying and managing versatile resources across the Internet. Collaborating the relational semantics of SLN with the classification semantics of the RSM can support richer semantic modeling in applications. This paper introduces the Resource Class Hierarchies into the SLN and investigates to cooperatively model with the RSM. The proposed approach can be used as a normalized semantic overlay of the Knowledge Grid environment. 1