Generating the fewest redundancy-free scheme trees from acyclic conceptual-model hypergraphs in polynomial time

Abstract

Generating the fewest redundancy-free scheme trees from conceptual-model hypergraphs is NP-hard [11]. We show, however, that the problem has a polynomial-time solution if the conceptual-model hypergraph is acyclic. We define conceptual-model hypergraphs, cycles, and scheme trees, and then present a polynomial-time algorithm and show that it generates the fewest redundancy-free scheme trees. As a practical application for the algorithm, we comment on its use for the design of "good" XML schemas for data storage.