Horn clauses and database dependencies (Extended Abstract)
Ronald Fagin · 1980
In the last year or so, a number of generalizations of these dependencies have appeared: Nicolas's mutual dependencies [Ni], which say that a relation is the join of three of its projections; Rissanen's and Aho, Beeri, and Ullman's join dependencies ([Ri], [ABU]), which generalize further to an arbitrary number of projections; Paradaens' transitive dependencies [Pa], which generalize both FDs and MVDs; Sagiv and Walecka's subset dependencies [SW] which generalize embedded MVDs; and Sadri and Ullman's template dependencies [SU], which generalize embedded join dependencies. The purpose of this paper is to help bring order to the chaos by presenting certain mathematical properties shared by all of these dependencies.