What are constraints on generalization and specialization?

  1. disjoint ness constraints.

  2. Completeness constraints.

Disjointness constraint specifies that the subclasses of the specialization must be disjoint .i.e. an entity can be a member of at most one of the subclasses of the specialization. The reverse of it is overlapping.

Completeness constraint is a participation constraint which may be

  1. Total

  2. Partial

Total specialization constraint tells that each entity in the super class must be a member of some subclass in the specialization. And partial specialization constraint allows an entity not to belong to any of the subclasses .Thus we do have the following 4 types of constraints on specialization:

  1. Disjoint, total

  2. Disjoint, partial

  3. Overlapping, total

  4. Overlapping, partial