Database Theory — ICDT '92

Volume 646 of the series Lecture Notes in Computer Science pp 376-390


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  • Marie DužíAffiliated withCharles University Computer Centre

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Informational capability of an attribute set is defined as the set of generated propositions. General data structures (comprising the set construct, tuple construct, functional as well as relational view) are compared for their informational capability using the definability relation. Relations of distinguishing capability (<dc) and comparison based on cardinality (≤bc) are defined on the set of attributes and examined with respect to the informational capability. Equivalent transformation of a database schema is defined and we prove that the general object-function schema can be equivalently transformed into a schema containing only unary (flat) attributes.