A Language for Generic Graph-Transformations

We define a class of graphs that represent object-oriented databases. Queries, updates and restructurings in such databases are performed by transformations of these graphs. We therefore first define five transformation-operations on this graph-class. Then we define generic transformations as a natural generalization of the concept of BP-completeness, originally defined for the relational database model. Our main result states that the language consisting of the five transformation-operations expresses exactly the generic transformations.