ELIMINATION OF INTERSECTION ANOMALIES FROM DATABASE SCHEMES.

The desirability of acyclic database scheme is well argued. When a scheme is described by multivalued dependencies, acyclicity means that the dependencies do not split each other's left-hand side and do not form intersection anomalies. Shown is that if the second condition fails to hold, the scheme can be amended so that it holds. The basic step is to add one attribute and some dependencies to resolve one intersection anomaly. This step generates an extension of the given scheme in which the anomaly does not exist. Analyzed is the repetitive use of the basic step and proven is that the transformation so defined removes all intersection anomalies. Finally characterized are a class of attributes that can be removed from the final scheme, leaving it acyclic.