Schemas Integration - Information Systems Reengineering, Integration and Normalization - page 272

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Fig. 7.12 Merge EER model by implied relationship in two cases

Substep 2.6. Merge entities by implied binary relationship.
X provides a view to A and B. There is a mapping between every unique instance
of entities A and B and every instance of entity X. There is a common field of entity
key to enable relationships built at each pair of instance in entity (A, B) and in entity
X. It is able to recover the instance of entity X, which is derived from entity (A, B)
(Fig. 7.12 ).

Step 3. Merge relationships.
Substep 3.1. Merge relationships by subtype relationship.
Case 1: Two relationships A and B are in the same role with different levels of
participation. The verification of this step is to identify the participation of two
identical schemas A and B with different levels of participation but with the same
role. The schema with the total participation will naturally dominate the schema
with the partial participation to ensure no information loss after transformation. As