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Issue No. 10 - October (1987 vol. 13)
ISSN: 0098-5589
pp: 1062-1072
T.T. Lee , Bell Communications Research
ABSTRACT
The structural properties of acyclic database schemas, especially the interrelationships between acyclic join dependencies and multivalued dependencies, are examined in this paper. The intersection closure of a database schema is a semilattice, which is usually represented by Hasse diagram in algebra. The Hasse diagram of a schema is analogous to the Bachman diagram of a network model. Based on the topological structures of Hasse diagrams, the acyclic join dependency is proved to be equivalent to a set of conflict-free multivalued dependencies. Furthermore, we show that if the Hasse diagram is loop free, then the corresponding set of multivalued dependencies is also contention-free. This result is consistent with previous results derived from the Bachman diagram.
INDEX TERMS
semilattice, Bachman diagram, conflict-free MVD's, contention free MVD's, Hasse diagram
CITATION
T.T. Lee, "An Information-Theoretic Analysis of Relational Databases?Part II: Information Structures of Database Schemas", IEEE Transactions on Software Engineering, vol. 13, no. , pp. 1062-1072, October 1987, doi:10.1109/TSE.1987.232848
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