Specialization rule: If an entity instance may belong to multiple subtypes or may belong to no subtype at all, how is the supertype/subtype design characterized?

Introduction / Context:
Two key decisions in supertype/subtype modeling are disjointness (disjoint vs. overlap) and completeness (total vs. partial). These affect constraints and implementation.

Given Data / Assumptions:

• The same supertype instance can appear in more than one subtype → overlap.
• An instance might be in no subtype → partial specialization.

Concept / Approach:
Overlap means an instance may exist in multiple subtypes simultaneously. Partial means membership in at least one subtype is not required. Together, they describe “overlap with partial specialization.”

Step-by-Step Solution:

Verification / Alternative check:
Modeling notations (crow’s foot, UML generalization sets) support these exact options.

Why Other Options Are Wrong:
Disjoint: Conflicts with multiple membership.
Total: Requires membership in at least one subtype, which the stem denies.

Common Pitfalls:
Confusing total/partial with disjoint/overlap; they are independent choices.

Final Answer:
Overlap with partial specialization