Computational problems related to the design of normal form relational schemas

Problems related to functional dependencies and the algorithmic design of relational schemas are examined. Specifically, the following results are presented: (1) a tree model of derivations of functional dependencies from other functional dependencies; (2) a linear-time algorithm to test if a functional dependency is in the closure of a set of functional dependencies; (3) a quadratic-time implementation of Bernstein's third normal form schema synthesis algorithm. Furthermore, it is shown that most interesting algorithmic questions about Boyce-Codd normal form and keys are NP-complete and are therefore probably not amenable to fast algorithmic solutions.