denition 1: The logic program can automatically be generwe include a clause which delivers all values of type ated from the type denitions b y a simple top down traversing algorithm on the syntax tree of a type C.
For each concept C imported in the API module tent to it. At least it has to fulll the following These equalities for the type denitions are true provided the database schema has a schema consis"well-typedness" axioms3: ing to EmpType directly but to its associated class As prescribed by the logic program, the pointerEmployee. Thereby, circular concept denitions are prevented. valued attribute head of DeptType is not refer