Rough Set Based Algorithm of Discovering Functional Dependencies for Relation Database

Functional dependency is an important concept in database research. It plays a fundamental role in the design of relation schema. Under the circumstance of semantics unknown or data relationship difficult to be defined, the problem we have to face is how to mine all possible full functional dependency behind datum. This paper gives top-down search algorithm based on indiscernibility relation to discover these dependencies. It improves traditional algorithm by reducing the redundant hypotheses of functional dependency and simplifying the process of verifying the hypotheses. Besides, the result excludes the possibility of partial dependency and distinguishes between direct functional dependency and transferable functional dependency.