The Size of Projections of Relations Satisfying a Functional Dependency

In this paper we consider tabulated data or relations in a data base __I__-_ system which are constrained by functional dependencies. This implies that the data in certain columns of each table is determined by the data contained in some other columns. The problem we address is that of the computation of the size of projections of the data on a subset of the columns. This may be viewed as the projection of data in some k dimensional space into a smaller subspace. We thus extend results we had previously obtained 1 [I for relations without functional dependencies to the case with functional dependencies.