Requests to: University of Dortmund

The implication problem is the problem of deciding whether a given set of dependencies entails other dependencies. Up to now, the entailment of excluded dependencies or independencies is only regarded on a metalogical level, which is not suitable for an automatic inference process. But, the inference of independencies is of great importance for new topics in database research like knowledge discovery in databases. In this paper, the expanded implication problem is discussed in order to decide entailment of dependencies and independencies. The main results are axiomatizations of functional, inclusion and multivalued independencies and the corresponding inference relations. Also, we discuss the use of independencies in knowledge discovery in databases and semantic query optimization.

Turning an Action Formalism Into a Planner|

ftp: kimo.informatik.uni-dortmund.de:pub/Report

Requests to: University of Dortmund

ftp: ftp-ai.informatik.uni-dortmund.de:pub/Report

Discovery of Data Dependencies in Relational Databases

Knowledge discovery in databases is not only the nontrivial extraction of implicit, previously unknown and potentially useful information from databases. We argue that in contrast to machine learning, knowledge discovery in databases should be applied to real world databases. Since real world databases are known to be very large, they raise problems of the access. Therefore, real world databases only can be accessed by database management systems and the number of accesses has to be reduced to a minimum. Considering this property, we are forced to use, for example, standard set oriented interfaces of relational database management systems in order to apply methods of knowledge discovery in databases. We present a system for discovering data dependencies, which is build upon a set oriented interface. The point of main effort has been put on the discovery of value restrictions, unary inclusion- and functional dependencies in relational databases. The system also embodies an inference rel..