Information Processing Letters
On Multisets in Database Systems
WMP '00 Proceedings of the Workshop on Multiset Processing: Multiset Processing, Mathematical, Computer Science, and Molecular Computing Points of View
A normal form for XML documents
ACM Transactions on Database Systems (TODS)
Efficient reasoning about a robust XML key fragment
ACM Transactions on Database Systems (TODS)
Functional dependencies in a relational database and propositional logic
IBM Journal of Research and Development
Unacceptable file operations in a relational data base
SIGFIDET '71 Proceedings of the 1971 ACM SIGFIDET (now SIGMOD) Workshop on Data Description, Access and Control
Numerical constraints on XML data
Information and Computation
The boyce-codd-heath normal form for SQL
WoLLIC'11 Proceedings of the 18th international conference on Logic, language, information and computation
Characterisations of multivalued dependency implication over undetermined universes
Journal of Computer and System Sciences
Foundations for a fourth normal form over SQL-Like databases
Conceptual Modelling and Its Theoretical Foundations
ACM Transactions on Database Systems (TODS)
Reasoning about functional and full hierarchical dependencies over partial relations
Information Sciences: an International Journal
Letting keys and functional dependencies out of the bag
APCCM '13 Proceedings of the Ninth Asia-Pacific Conference on Conceptual Modelling - Volume 143
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The theory of functional dependencies is based on relations, i.e. sets of tuples. Over relations, the class of functional dependencies subsumes the class of keys. Commercial database systems permit the storage of bags of tuples where duplicate tuples can occur. Over bags, keys and functional dependencies interact differently from how they interact over relations. We establish finite ground axiomatizations of keys and functional dependencies over bags, and show a strong correspondence to goal and definite clauses in classical propositional logic. We define a syntactic Boyce-Codd-Heath Normal Form condition, and show that the condition characterizes schemata that will never have any redundant data value occurrences in their instances. The results close the gap between the existing set-based theory of data dependencies and database practice where bags are permitted.