Now showing items 1-3 of 3

    • Integrity constraints revisited 

      Demolombe, Robert; Jones, Andrew (Universitat Politècnica de Catalunya. Departament de Llenguatges i Sistemes Informàtics, 1993)
      Conference report
      Open Access
      When computerised databases began to be used in business applications, there naturally arose a concern with how the integrity the stored data could be checked. This task was irnplemented by large sets of programs, depending ...
    • Reasoning about the safety of information: from logical formalization to operational definition 

      Cholvy, Laurence; Demolombe, Robert (Universitat Politècnica de Catalunya. Departament de Llenguatges i Sistemes Informàtics, 1994)
      Conference report
      Open Access
      We assume that safety of information stored in a database depends on the reliability of the agents who have performed the insertions in the database. We present a logic S to represent information safety, and to derive ...
    • Strategies for the computation of conditional answers 

      Demolombe, Robert (Universitat Politècnica de Catalunya. Departament de Llenguatges i Sistemes Informàtics, 1990)
      Conference report
      Open Access
      We consider bere non-Horn Deductive Data Bases {DDB). In this con­ text there are many queries whose answer is : I don't know. A first ap­proach to reduce the number of such answers is to add information, like default ...