A simplied universal relation assumption and its properties
ACM Transactions on Database Systems (TODS)
On the Equivalence of Database Models
Journal of the ACM (JACM)
On the Desirability of Acyclic Database Schemes
Journal of the ACM (JACM)
Degrees of acyclicity for hypergraphs and relational database schemes
Journal of the ACM (JACM)
Principles of Database Systems
Principles of Database Systems
SIGMOD '81 Proceedings of the 1981 ACM SIGMOD international conference on Management of data
Elimination of intersection amomalies from database schemes
PODS '83 Proceedings of the 2nd ACM SIGACT-SIGMOD symposium on Principles of database systems
Improving database schemes by adding attributes
PODS '83 Proceedings of the 2nd ACM SIGACT-SIGMOD symposium on Principles of database systems
PODS '82 Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems
Database Decomposition into Fourth Normal Form
VLDB '83 Proceedings of the 9th International Conference on Very Large Data Bases
Acyclic Database Schemes (of Various Degrees): A Painless Introduction
CAAP '83 Proceedings of the 8th Colloquium on Trees in Algebra and Programming
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Acyclic database schemes have attracted a lot of interest because of the nice properties enjoyed by such schemes. Recently some new acyclicity conditions that are strictly stronger than the normal α-acyclicity have been introduced by Fagin. Because of increased requirements, the database schemes in the new classes have some further useful properties that are not shared by α-acyclic schemes. Therefore the new classes have practical relevance.A database designer may work in terms of attribute sets and data dependencies, and not only in terms of database schemes. Thus it is important to have a characterization for the acyclic schemes of various degree in terms of data dependencies. For α-acyclic schemes such a characterization exists, but for the new classes the question has been open. In this paper we provide characterizations for β-, γ- and Berge-acyclic database schemes. The characterizations can be stated in a simple form: thus they should be useful for the database designer.