An algorithm for determining minimal reduced-coverings of acyclic database schemes

Abstract

This paper reports an algorithm (DTV) for determining the minimal reduced-covering of an acyclic database scheme over a specified subset of attributes. The output of this algorithm contains not only minimum number of attributes but also minimum number of partial relation schemes. The algorithm has complexityO(⋎N⋎·⋎E⋎2), where ⋎N⋎ is the number of attributes and ⋎E⋎ the number of relation schemes. It is also proved that for Berge, γ or β acyclic database schemes, the output of algorithm DTV maintains the acyclicity correspondence.