Updating Semantic Web Data

The basic data model for the Semantic Web is the Resource Description Framework (RDF). From a data management point of view, it resembles a lightweight knowledge base. In this paper we address updates in RDF. It is known that the semantics of updates for data models becomes unclear when the model turns, even slightly, more general than a simple relational structure. Viewing RDF as a knowledge base, and using the formalism of Katsuno-Mendelzon, we define semantics for updates in RDF. Then we show that RDF as a representation system does not have enough expressiveness to state updates satisfying the Katzuno-Mendelzon framework. Hence, we study the behavior of classical update operations in the framework of RDF, and propose versions of such updates based on approximations. Finally, we study how to compute these operations, which for erase are particularly complex, and give complexity bounds for them. 1