On Restructuring Nested Relations in Partitioned Normal Form

Relations in partitioned normal form are an important subclass of nested relations. This paper is concerned with the problem of restructuring relations in partitioned normal form to new and potentially very different schemes. The main problem with restructuring is to minimize the amount of information lost during the transformation. A new restructuring operator is defined which minimizes that loss of information. Its definition is refined step by step into more and more computationally efficient versions.