Generalization vs. specialization: Is generalization the process of defining a more general supertype from a set of more specialized subtypes?

Difficulty: Easy

Correct Answer: Correct

Explanation:


Introduction / Context:
Two complementary modeling operations exist: generalization and specialization. Specialization starts with a general entity and creates subtypes; generalization starts with several specific entities and abstracts a common supertype. Distinguishing these is central to flexible data modeling.



Given Data / Assumptions:

  • Multiple specific entity types share common attributes or keys.
  • The modeler wants to factor out the commonalities.
  • We are describing conceptual operations, not tied to a specific tool.


Concept / Approach:
Generalization identifies shared identity and attributes across distinct but related entities and defines a new supertype to capture those shared properties. For instance, Patient and Physician may be generalized to Person to hold name, birth_date, and address. The original entities become subtypes that add unique attributes (license_number for Physician, insurance_id for Patient).



Step-by-Step Solution:

Analyze existing entities to find common keys and attributes.Extract these into a new supertype with a single, unifying identifier.Refactor the original entities as subtypes that inherit from the supertype.Define disjoint/overlapping and total/partial participation rules as needed.


Verification / Alternative check:
After generalization, queries for common attributes occur against the supertype; subtype-specific queries still work but benefit from shared identity and reduced redundancy.



Why Other Options Are Wrong:

  • “Incorrect” contradicts standard terminology.
  • Restricting to UML or to total participation is unnecessary; the concept exists in ER/EE-R and does not depend on coverage.


Common Pitfalls:
Overgeneralizing unrelated entities, which can produce artificial supertypes and complicate constraints. Always validate generalization with real business semantics.



Final Answer:
Correct

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