Synthesizing third normal form relations from functional dependencies
ACM Transactions on Database Systems (TODS)
Multivalued dependencies and a new normal form for relational databases
ACM Transactions on Database Systems (TODS)
Independent components of relations
ACM Transactions on Database Systems (TODS)
A generalized access path model and its application to a relational data base system
SIGMOD '76 Proceedings of the 1976 ACM SIGMOD international conference on Management of data
A complete axiomatization for functional and multivalued dependencies in database relations
SIGMOD '77 Proceedings of the 1977 ACM SIGMOD international conference on Management of data
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Several areas of relational database research rely on techniques for transforming the schema (intention) and underlying occurrence structures (extension) of a database. In each of these areas, it is imperative to know what information from the original database is preserved by the restructuring operation. This paper examines the extent to which an important class of relational database transformations preserves information. This is accomplished in two steps. First, a formal characterization of "information content" is presented based on the set of functional and nonfunctional associations among attributes of a relational database. Second, formal conditions are presented indicating the extent to which these associations are preserved. Based on these conditions, the information preserving properties of several well-known relational transformations are described. Some problems in maintaining these properties under updates are also discussed.