Fuzzy relational databases: Representational issues and reduction using similarity measures
✍ Scribed by Prade, Henri ;Testemale, Claudette
- Publisher
- John Wiley and Sons
- Year
- 1987
- Tongue
- English
- Weight
- 782 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0002-8231
No coin nor oath required. For personal study only.
✦ Synopsis
Until now, the idea of a fuzzy database has been investigated along different lines: Some authors have dealt with the imprecision of attribute values by modeling, using fuzzy similarity relations, the extent to which these values could be regarded as interchangeable.
Others have used possibility distributions for representing fuzzily known or incompletely known attribute values. The first approach, which cannot accommodate incomplete information, is restated in the framework of rough sets extended to fuzzy relations. Besides, in the second one, similarity measures between attribute values can be introduced and computed; then a comparison of the two approaches is provided. The proposed similarity measure, based on a fuzzy Hausdorff distance, estimates the mismatch between two possibility distributions. From storage and query-evaluation points of view, it may be interesting to gather items having similar attribute values. Thus the similarity measures previously considered can be used'for the reduction of the fuzzy database.
When several items have sufficiently similar values for each attribute in a relation, the reduction is performed by taking for each attribute the union of these similar values. The consequences of the reduction process on query evaluation are studied.
I. Introduction
Recent research in fuzzy databases has been motivated by the need for managing imprecisely known or linguistically stated data and for modeling semantic proximity between values. Two different approaches have emerged recently for accommodating the idea of fuzziness in the framework of relational databases. Namely, Buckles and Petry [l-3] (see also Anvari and Rose [4] for a related *This paper was presented at the 1st Congress of the International Fuzzy Systems Association (Palma de Mallorca, July 1-6, 1985).