Generalized dependencies in relational databases
A new type of dependencies in a relational database model introduced in [5] is investigated. If b is an attribute, A is a set of attributes then it is said that b (p, g, )-depends on A, in notation A ^^ b, in a database relation r if there are no q + 1 tuples in r such that they have at most p diffe...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
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1998
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| Sorozat: | Acta cybernetica
13 No. 4 |
| Kulcsszavak: | Számítástechnika, Kibernetika |
| Tárgyszavak: | |
| Online Access: | http://acta.bibl.u-szeged.hu/12602 |
| Tartalmi kivonat: | A new type of dependencies in a relational database model introduced in [5] is investigated. If b is an attribute, A is a set of attributes then it is said that b (p, g, )-depends on A, in notation A ^^ b, in a database relation r if there are no q + 1 tuples in r such that they have at most p different values in each column of A, but 9 + 1 different values in 6. (1, l)-dependency is the classical functional dependency. Let ¿7{A) denote the set {b: A 6}. The set function J\ 2n —> 2 n becomes a closure if p = q. Results on representability of closures by (p, p)-dependencies are presented. |
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| Terjedelem/Fizikai jellemzők: | 431-438 |
| ISSN: | 0324-721X |