Avoiding Pitfalls in Data Modeling - High-Performance Web Databases: Design, Development, and Deployment - page 279

Exhibit 18-4. Access path versus business rules relationships.

In the example of man marries woman, if a multicultural perspective is
included, the relationship might no longer be one-to-one. The same is true
if a time dimension is added.

Data modeling convention may require the
modeler to name both directions of the flow in the relationship. It is easy to
fall into the trap of semantic inconsistency between the two directions. The
inconsistency can be eliminated with multiple relationships between a pair
of entities.

Semantics in Relationship.