Invariance Properties of the Constant-Complement View-Update Strategy

The constant-complement approach is one of the principal strategies for defining the reflections of database view updates. The purpose of this paper is twofold. First, a self-contained presentation of the strategy itself is given. Second, two fundamental invariance problems are examined. In admissibility invariance, the question of when the translatability of a view update is independent of the view state is considered. In reflection invariance, the question of when a view update is independent of the choice of complement is considered. In addition to a summary of existing results for both forms of invariance, new results for reflection invariance are presented.