Relationship Participation
Also referred to as “minimum cardinality”
Mandatory Participation
- An instance of a given entity must definitely match an instance of a second entity
- e.g., each student must enroll in exactly one course
Optional Participation
- An instance of a given entity does not necessarily participate in the relationship
- lower bound of cardinality is zero
- e.g., a faculty member teaches zero, one, or two courses
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