Minimizing indefinite information in disjunctive deductive databases

  • Monica D. Barback
  • Jorge Lobo
  • James J. Lu
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 646)


A natural way to formalize certain incomplete information in databases is through the use of disjunctions, for example A ∨ B. Typically, the meaning of such indefinite information is based on the classical interpretation of the connective ∨, We argue in this paper that this treatment is not strong enough for dealing with a large class of indefinite information. Instead, we propose an intuitively more meaningful definition in which asserting a disjunction also invaliudates any subsumed disjunction, hence exhibiting a non-monotonic behavior. First, we examine a class of databases that can be stratified in a way similar to [1]. For this class of databases, we derive a meaning that coincides with the above motivation. Next, we present an algorithm for transforming an arbitrary database P to a set of stratifiable databases from which the meaning of P is obtained. It turns out that computing answers under this semantics can be done in polynomial time.


Logic Program Dependency Graph Predicate Symbol Stratify Model Ground Instance 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1992

Authors and Affiliations

  • Monica D. Barback
    • 1
  • Jorge Lobo
    • 2
  • James J. Lu
    • 3
  1. 1.Northwestern UniversityEvanston
  2. 2.University of Illinois ChicagoChicago
  3. 3.Bucknell UniversityLewisburg

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