New Directions For Uncertainty Reasoning In Deductive Databases

This paper contributes a novel approach to nonmonotonic uncertainty reasoning, which is ubiquitous in many real-life applications. Founded on the paradigm of conditional probabilities we develop a rule-based calculus and prove that it is sound, even in the presence of incomplete information. Thus the merits of doing consistent judgements in uncertain domains and the advantages of modularity and incrementality of rulebased application development come together. We also can offer mechanisms to trace down inconsistencies that may be hidden in very large collections of uncertain rules. As next-generation applications will have to handle vast amounts of uncertain data, an integration into databases is mandatory. We give a direct implementation of our calculus on top of a database system with a DATALOG-interface. In this way we extend current database technology towards providing new applications with new suitable primitives and with a database platform for coping with uncertainty

Database Support for Problematic Knowledge

Recently substantial research efforts have been spent on extending database technology in various ways towards a better support of applications of the nineties. In contrast, the tough problems of adding the right uncertainty reasoning capabilities have received relatively modest attention despite evident importance. Among the many faces of uncertainty we focus on what we call problematic knowledge, which is - e. g. - inherent in what-if decision scenarios. Based on a rule calculus with probability intervals introduced lately [GKT 91] we show how to do rule chaining under independence and how to add comparative probability. Also a method for reasoning with uncertain facts, founded on the notions of maximal context and detachment, is given. Full database support can be given to the calculus. We discuss some aspects of the optimization problem and how to deliver uncertainty reasoning to the user's application by interoperability in a heterogeneous database environment