UML vs. EER — Meaning of “Complete” in UML Generalization In class modeling, the UML constraint “Complete” on a generalization corresponds to which Enhanced-ER (EER) specialization rule?
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AOverlapping rule
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BDisjoint rule
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CTotal specialization rule
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DPartial specialization rule
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EMutual exclusivity rule only for two subtypes
Answer
Correct Answer: Total specialization rule
Explanation
Introduction / Context:Different modeling notations express similar ideas with different terms. Bridging UML class diagrams and EER helps data modelers translate constraints correctly when moving between conceptual and logical designs.
Given Data / Assumptions:
- UML uses “Complete/Incomplete” for generalization sets.
- EER uses “Total/Partial” specialization rules.
- We must map UML “Complete” to the appropriate EER rule.
Concept / Approach:In UML, “Complete” means every instance of the supertype must belong to at least one subtype. In EER terms, this is the “Total specialization rule.” The disjoint/overlapping dimension is orthogonal: it specifies whether an instance may belong to multiple subtypes simultaneously. Therefore, “Complete” aligns with “Total,” not with “Disjoint” or “Overlapping,” and certainly not with “Partial.”
Step-by-Step Solution:Translate UML “Complete” → every supertype instance is covered by subtypes.Recall EER terms: Total = coverage; Partial = not all supertype instances covered.Identify that “Complete” = Total specialization.Select “Total specialization rule.”
Verification / Alternative check:Modeling references show two independent dimensions: coverage (Complete/Incomplete ↔ Total/Partial) and overlap (Disjoint/Overlapping). This confirms the mapping.
Why Other Options Are Wrong:
- Overlapping/Disjoint: Address whether subtypes can overlap, not coverage.
- Partial specialization: Opposite of Complete/Total.
- Mutual exclusivity only for two subtypes: A narrow, nonstandard restatement of disjointness, not coverage.
Common Pitfalls:Conflating coverage with exclusivity; you can have Total + Disjoint or Total + Overlapping depending on the domain.
Final Answer:Total specialization rule