Ternary relation ship is a relationship wherein 3 entity sets particpate.
Aggregation is just a abstraction through which relationships are treated as higher level entities
Works is a ternary relationship with 3 entity sets(Job,Employee,Branch)
Aggregation:
If I add one more entity set (Manager) to above ER with a relation ship set Manages(Manager,Employee,Job). Then we have redundant information stored at Manages.
So what is done to remove it is:
The Relationship set (Works) and the entity sets(Job,Employee,Branch) are together treated as only one entity set X. Now this X is related to Manager via the binary relationship manages.
