An example application

With these operations, you will be able to construct most other operations you may need. For example, if your application domain uses an immediate constituent model, one way of modeling this is to have, in each object type, a feature called "parent", which is an id_d pointing to the parent object. Then a number of desirable operations can easily be implemented in terms of the above operations:

• Get immediate constituents of object
• Get parent of object
• Get siblings (through judicious use of the two above operations)
• is_c_commanding (a boolean)

etc. etc.