Abstract
A new way of using database design theory to facilitate the formulation of precise or imprecise queries in crisp or fuzzy relational databases is proposed. It is shown that a specific representation of multivalued dependencies between attributes in a database can be equivalently translated into the formal framework of qualitative Markov trees. Any imprecise query can then be modelled by a set of belief functions on a set of nodes in the tree to be propagated to some other nodes. The dependency structure can be used to reveal restrictions in the choice of composite attribute values even during formulation of queries.KeywordsFuzzy SetsBelief FunctionsRelational DatabasesNon-First-Normal-Form SchemesQuery Languages
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