Abstract
Traditionally, databases allow only to store positive information. This restriction may cause problems in certain applications where information may be incomplete and a symmetric treatment of positive and negative information is required. We extend our knowledge system framework in such a way that it accommodates negative information and possibly inconsistent knowledge bases.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
Notes
In earlier work, we used ‘–’ to denote weak negation (expressing non-truth) and‘~’Afor strong negation (expressing falsity) in order to distinguish them from classical negation ¬ which can be viewed as a special case of either of them: both collapse to ¬ if only total coherent partial models are admitted (i.e. it is not possible to distinguish between falsity and non-truth in classical logic). The meaning of negation in relational and deductive databases in connection with the Closed-World Assumption is very ambiguous. If the CWA (identifying falsity with non-truth) is only applied at the meta-level, database negation corresponds to weak negation in semi-partial logic whose consequence relation is isomorphic to classical consequence. If the CWA, however, is implemented within the inference relation, database negation corresponds to strong negation (expressing falsity) in a fragment of full partial logic.
This corresponds to the AGM expansion of ‘belief sets’, see Gärdenfors, 1988.
Author information
Authors and Affiliations
Rights and permissions
Copyright information
© 1998 Springer Science+Business Media New York
About this chapter
Cite this chapter
Wagner, G. (1998). Principles of Non-Positive Knowledge Systems. In: Foundations of Knowledge Systems. The Kluwer International Series on Advances in Database Systems, vol 13. Springer, Boston, MA. https://doi.org/10.1007/978-1-4615-5723-4_10
Download citation
DOI: https://doi.org/10.1007/978-1-4615-5723-4_10
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4613-7621-7
Online ISBN: 978-1-4615-5723-4
eBook Packages: Springer Book Archive