Now showing items 21-40 of 415

    • Equivalences among Aggregate Queries with Negation 

      Cohen, S; Nutt, W; Sagiv, Y (Association for Computing Machinery (ACM), 2005)
      Query equivalence is investigated for disjunctive aggregate queries with negated subgoals, constants and comparisons. A full characterization of equivalence is given for the aggregation functions count, max, sum, prod, ...
    • A conceptual architecture for semantic web services development and deployment 

      Pahl C (Inderscience Publishers, 2005)
      Several extensions of the Web Services Framework (WSF) have been proposed. The combination with Semantic Web technologies introduces a notion of semantics, which can enhance scalability through automation. Service composition ...
    • Stream Integration Techniques for Grid Monitoring 

      Cooke, A; Gray, AJG; Nutt, W (Springer, 2005)
      Grids are distributed systems that provide access to computational resources in a transparent fashion. Providing information about the status of the Grid itself is called Grid monitoring. As an approach to this problem, ...
    • Rewriting queries with arbitrary aggregation functions using views 

      Cohen, S; Nutt, W; Sagiv, Y (Association for Computing Machinery (ACM), 2006)
      The problem of rewriting aggregate queries using views is studied for conjunctive queries with arbitrary aggregation functions and built-in predicates. Two types of queries over views are introduced for rewriting aggregate ...
    • Strategies for Query Unnesting in XML databases 

      May, N; Helmer, S; Moerkotte, G (Association for Computing Machinery (ACM), 2006)
    • Algebraic Translation and Optimization of (Nested) XPath Expressions 

      Brantner, M; Kanne, CC; Helmer, S; Moerkotte, G (IEEE, 2006)
      The XPath language incorporates powerful primitives for formulating queries containing nested subexpressions which are existentially or universally quantified. However, even the best published approaches for evaluating ...
    • Reasoning on temporal class diagrams: Undecidability results 

      Artale, A (Springer Verlag (Germany), 2006)
      This paper introduces a temporal class diagram language useful to model temporal varying data. The atemporal portion of the language contains the core constructors available in both EER diagrams and UML class diagrams. The ...
    • A Change-based Approach to Software Evolution 

      Robbes R; Lanza M (2007)
      Software evolution research is limited by the amount of information available to researchers: Current version control tools do not store all the information generated by developers. They do not record every intermediate ...
    • Deciding equivalences among conjunctive aggregate queries 

      Cohen, S; Nutt, W; Sagiv, Y (Association for Computing Machinery, 2007)
      Equivalence of aggregate queries is investigated for the class of conjunctive queries with comparisons and the aggregate operators count, count-distinct, min, max, and sum. Essentially, this class contains unnested SQL ...
    • Evolving objects in temporal information systems 

      Artale, A; Parent, C; Spaccapietra, S (Springer Verlag (Germany), 2007)
    • Notes on Logics of Metric Spaces 

      Kutz, O (Springer Verlag (Germany), 2007)
      In [14], we studied the computational behaviour of various first-order and modal languages interpreted in metric or weaker distance spaces. [13] gave an axiomatisation of an expressive and decidable metric logic. The main ...
    • Semantic model-driven architecting of service-based software systems 

      Pahl, C (Elsevier, 2007)
      Model-driven development is a software development framework that emphasises model-based abstraction and automated code generation. Service-based software architectures benefit in particular from semantic, ontology-based ...
    • Answering queries over incomplete data stream histories 

      Gray, JG; Nutt, W; Williams, MH (Emerald, 2007)
      Purpose – Distributed data streams are an important topic of current research. In such a setting, data values will be missed, e.g. due to network errors. This paper aims to allow this incompleteness to be detected and ...
    • Developing domain ontologies for course content 

      Boyce S; Pahl C (International Forum of Educational Technology & Society, 2007)
      Ontologies have the potential to play an important role in instructional design and the development of course content. They can be used to represent knowledge about content, supporting instructors in creating content or ...
    • An ontology for software component matching 

      Pahl C (Springer Verlag, 2007)
      Matching is a central activity in the discovery and assembly of reusable software components. We investigate how ontology technologies can be utilised to support software component development. We use description logics, ...
    • The influence of inertial loading on color gamut properties of a TFT LCD display 

      Grbec S; Tkalčič M; Diaci J (2008)
      The article presents the results of an experiment where a 7 in. TFT LCD display was exposed to harmonic vibration with acceleration amplitudes up to 200 m/s and frequency sweep in the range between 40 Hz and 1.5 kHz. The ...
    • Representing and reasoning over a taxonomy of part-whole relations 

      Keet, CM; Artale, A (IOS Press, 2008)
      Many types of part-whole relations have been proposed in the literature to aid the conceptual modeller to choose the most appropriate type, but many of those relations lack a formal specification to give clear and unambiguous ...
    • Expressing and verifying contracts with abductive logic programming 

      Alberti, M; Chesani, F; Gavanelli, M; Lamma, E; Mello, P; Montali, M; Torroni, P (Taylor & Francis (Routledge): SSH Titles, 2008)
      SCIFF is a declarative language, based on abductive logic programming, that accommodates forward rules, predicate definitions, and constraints over finite domain variables. Its abductive declarative semantics can be related ...
    • Content-driven design and architecture of E-learning applications 

      Pahl C (ACTA Press, 2008)
      E-learning applications combine content with learning technology systems to support the creation of content and its delivery to the learner. In the future, we can expect the distinction between learning content and its ...
    • An ontological framework for web service processes 

      Pahl C; Barrett R (World Scientific Publishing, 2008)
      The process notion is central in computing. Business processes and workflow processes are essential elements of software systems implementations. Processes are connected to notions of interaction and composition. The Web ...