Consultas con agrupamiento basado en similitud

The fuzzy sets allow for the representation of vague concepts, where membership of an object could be gradual. The use of this theory in the data bases has been proposed. As result of that, the fuzzy relational model GEFRED has emerged, as well as the fuzzy extended Entity-Relationship model FuzzyEER and the fuzzy querying language FSQL, among others. These extensions include some forms of fuzzy attributes, such as the so-called Type 3. These attributes have values in a set of labels provided with a fuzzy similarity relation, which is an extension of equivalence relations in the fuzzy set theory. The implications of such attributes in partitioned query operators have not been previously explored. The contribution of this paper is on the syntactic and semantic definition of an extension to SQL, in order to allow for partitioned queries with Type 3 fuzzy attributes in grouping criteria. This extension increases the expressive power of the database language with respect to previous proposals