Normal Form Relation Schemes: A New Characterization

  János Demetrovics Gusztáv Hencsey Leonid Libkin Ilya Muchnik

Abstract:

  A new characterization of relational database schemes in normal forms is given. This characterization is based on the properties of the semilattice of closed sets of attributes. For the problems testing third and Boyce-Codd normal forms, which are known to be -complete for relation schemes, this new characterization helps establish polynomial algorithms if the input is a relation (matrix) rather than a relation scheme. The problem of approximation of an arbitrary family of functional dependencies by one in a normal form is also addressed.

 Gyenizse Pal 1996. Szeptember 4. Szerda 13:57:13 MET DST