Now showing items 1-20 of 364

  • Describing Database Objects in a Concept Language Environment 

    Artale A; Cesarini F; Soda G (1996)
    We formally investigate the structural similarities and differences existing between object database models and concept languages establishing a correspondence between the two environments. Object database models deal with ...
  • An Epistemic Operator for Description Logics 

    Donini, FM; Lenzerini, M; Nardi, D; Nutt, W; Schaerf, A (Elsevier, 1998)
    Description logics (also called terminological logics, or concept languages) are fragments of first-order logic that provide a formal account of the basic features of frame-based systems. However, there are aspects of ...
  • Index structures for efficiently accessing fuzzy data including cost models and measurements 

    Boss, B; Helmer, S (Elsevier, 1999)
    Recently, the call for database management systems (DBMS) with uncertainty capabilities is getting stronger. Many of the existing approaches to modeling uncertainty in database management systems are based on the theory ...
  • Efficient use of parallel libraries on heterogeneous Networks of Workstations 

    Clematis, A; Dodero, GM; Gianuzzi, V (Elsevier, 2000)
    The paper is motivated by efficiency considerations about porting mathematical software from Massively Parallel Processors (MPPs) to Networks of Workstations (NOWs). Heterogeneity of the network is the major obstacle to ...
  • The implementation and performance of compressed databases 

    Westmann, T; Kossmann, D; Helmer, S; Moerkotte, G (Association for Computing Machinery; 1999, 2000)
    In this paper, we show how compression can be integrated into a relational database system. Specifically, we describe how the storage manager, the query execution engine, and the query optimizer of a database system can ...
  • Anatomy of a native XML base management system 

    Fiebig, T; Helmer, S; Kanne, CC; Moerkotte, G; Neumann, J; Schiele, R; Westmann, T (Springer Verlag (Germany), 2002)
    Several alternatives to manage large XML document collections exist, ranging from file systems over relational or other database systems to specifically tailored XML base management systems. In this paper we give a tour ...
  • Evaluating different approaches for indexing fuzzy sets 

    Helmer, S (Elsevier, 2003)
    Providing efficient query processing in database systems is one step towards gaining acceptance of such systems by end users. We propose several techniques for indexing fuzzy sets in databases to improve the query evaluation ...
  • XML-Datenbanken und ihre Anwendung 

    Helmer, S; Kanne, CC; Moerkotte, G (2003)
    Due to its fast proliferation,the amount of XML data is steadily increasing and XML-based applications become more and more complex. This requires effective and efficient methods to manage large amounts of persistent XML. ...
  • A performance study of four index structures for set-valued attributes of low cardinality 

    Helmer, S; Moerkotte, G (Springer Verlag (Germany), 2003)
    The efficient retrieval of data items on set-valued attributes is an important research topic that has attracted little attention so far. We studied and modified four index structures (sequential signature files, signature ...
  • A framework for the development of personalized, distributed web-based configuration systems 

    Ardissono, L; Felfernig, A; Friedrich, G; Goy, A; Jannach, D; Petrone, G; Schafer, R; Zanker, M (Aaai American Association of Artificial, 2003)
    For the last two decades, configuration systems relying on AI techniques have successfully been applied in industrial environments. These systems support the configuration of complex products and services in shorter time ...
  • Configuration knowledge representations for Semantic Web applications 

    Felfernig, A; Friedrich, G; Jannach, D; Stumptner, M; Zanker, M (Cambridge University Press, 2003)
    Today's economy exhibits a growing trend toward highly specialized solution providers cooperatively offering configurable products and services to their customers. This paradigm shift requires the extension of current ...
  • Managing evolution and change in web-based teaching and learning environments 

    Pahl C (Pergamon Press (Elsevier), 2003)
    The state of the art in information technology and educational technologies is evolving constantly. Courses taught are subject to constant change from organisational and subject-specific reasons. Evolution and change affect ...
  • Logics of metric spaces 

    Kutz O; Wolter F; Sturm H; Suzuki N; Zakharyaschev M (2003)
    We investigate the expressive power and computational properties of two different types of languages intended for speaking about distances. First, we consider a first-order language FM the two-variable fragment of which ...
  • Engineering a new abstraction layer to optimize the HEP analysis process 

    Amaral, V; Helmer, S; Moerkotte, G (Institute of Electrical and Electronics Engineers (IEEE), 2004)
    Presently, in the new high-energy physics experiments we are observing a growing complexity in the interfaces of the analysis tools. As a consequence, end users have to master programming, understand complex frameworks and ...
  • Evaluating lock-based protocols for cooperation on XML documents 

    Helmer, S; Kanne, CC; Moerkotte, G (Association for Computing Machinery; 1999, 2004)
    We discuss four different core protocols for synchronizing access to and modifications of XML document collections. These core protocols synchronize structure traversals and modifications. They are meant to be integrated ...
  • E-connections of abstract description systems 

    Kutz, O; Lutz, C; Wolter, F; Zakharyaschev, M (Elsevier, 2004)
    Combining knowledge representation and reasoning formalisms is an important and challenging task. It is important because non-trivial AI applications often comprise different aspects of the world, thus requiring suitable ...
  • Konzepte zur flexiblen Konfiguration von Finanzdienstleistungen 

    Felfernig, A; Mehlau, J; Wimmer, A; Zanker, M; Russ, C (2004)
    Integriertes Kundenmanagement über alle Vertriebskanäle hinweg und die Steigerung der Kundenzufriedenheit durch spezifische kundenindividuelle Beratung und Leistungserstellung sind zentrale Ansätze von Finanzdienstleistern, ...
  • Data mining technology for the evaluation of learning content interaction 

    Pahl, C (Association for the Advancement of Computing in Education, 2004)
    Interactivity is central for the success of learning. In e-learning and other educational multimedia environments, the evaluation of interaction and behaviour is particularly crucial. Data mining – a non-intrusive, objective ...
  • The Relational Grid Monitoring Architecture: Mediating Information about the Grid 

    Cooke AW; Gray AJG; Nutt W; Magowan J; Oevers M; Taylor P; Cordenonsi R; Byrom R; Cornwall L; Djaoui A; Field L; Fisher SM; Hicks S; Leake J; Middleton R; Wilson A; Zhu X; Podhorszki N; Coghlan B; Kenny S; O'Callaghan D; Ryan J (2004)
    We have developed and implemented the Relational Grid Monitoring Architecture (R-GMA) as part of the DataGrid project, to provide a flexible information and monitoring service for use by other middleware components and ...
  • A flexible error resilient scheme for JPEG 2000 

    Tillo T.; Grangetto M.; Olmo G. (IEEE, 2004)
    Nowadays, wireless multimedia applications are experiencing a rapid growth; in this scenario, challenging obstacles, such as packet losses due to congestion and band limitation along with bit-level error corruption, require ...