Inferring minimal rule covers from relations

Abstract

An implication rule Q→R is roughly a statement of the form "for all objects in the database, if an object has Q then it has also R". We introduce a definition of minimal cover for the set of implication rules that hold in a relation, by analogy with earlier work on functional dependencies, and present an approach to computing it. The core of the proposed approach is an algorithm for inferring a reduced cover containing only maximally general rules, i.e., such that no attribute-value pair on any left side is redundant. We study the computational complexity of the proposed approach and present an experimental comparison with another method that confirms its validity, especially when the number of attributes in the database is limited.