Normal form relation schemes a new characterization /

A new characterization of relational database schemes in normal forms is given. This characterization is based on the properties of the semilattice of closed sets of attributes. For the problems testing third and Boyce-Codd normal forma, which are known to be ^//'-complete for relation schemes,...

Teljes leírás

Elmentve itt :
Bibliográfiai részletek
Szerzők: Demetrovics János
Hencsey Gusztáv
Libkin Leonid O.
Muchnik Ilya
Dokumentumtípus: Cikk
Megjelent: 1992
Sorozat:Acta cybernetica 10 No. 3
Kulcsszavak:Számítástechnika, Kibernetika
Tárgyszavak:
Online Access:http://acta.bibl.u-szeged.hu/12502
Leíró adatok
Tartalmi kivonat:A new characterization of relational database schemes in normal forms is given. This characterization is based on the properties of the semilattice of closed sets of attributes. For the problems testing third and Boyce-Codd normal forma, which are known to be ^//'-complete for relation schemes, this new characterization helps establish polynomial algorithms if the input is a relation (matrix) rather than a relation scheme. The problem of approximation of an arbitrary family of functional dependencies by one in a normal form is also addressed.
Terjedelem/Fizikai jellemzők:141-153
ISSN:0324-721X