UML associations vs aggregations: is aggregation a stronger form of association shown with a solid (filled) diamond at the aggregate end?

Introduction / Context: In Unified Modeling Language (UML), association, aggregation, and composition model “has-a” relationships. Visual notation matters: the diamond adornment differentiates these relationships. The statement claims aggregation uses a solid (filled) diamond and is a stronger association.

Given Data / Assumptions:

• UML distinguishes aggregation (shared-ownership) from composition (strong ownership, whole–part lifecycle).
• Diagram adornments: hollow (white) diamond for aggregation; solid (filled) diamond for composition.
• Association lines without diamonds express simple navigable or non-navigable links.

Concept / Approach: Aggregation is a specialized association indicating a whole–part with weak ownership. Composition is the stronger form: the part’s lifecycle is bound to the whole (if the whole is destroyed, the parts go with it). Therefore, the solid diamond denotes composition, not aggregation. Aggregation uses a hollow diamond.

Step-by-Step Solution:

Verification / Alternative check: Consult any standard UML reference: symbol tables consistently use hollow for aggregation, solid for composition.

Why Other Options Are Wrong:

• Correct: Would invert the standard UML meaning.
• Only true for composition: Indeed, the solid diamond belongs to composition, confirming the statement is incorrect for aggregation.
• Depends on tool colors: Decoration is semantic, not color theme–dependent.
• No diamond: Without a diamond, it is a plain association, not aggregation.

Common Pitfalls: Confusing aggregation and composition; assuming tool-specific visuals change UML semantics; forgetting lifecycle coupling in composition.

Final Answer: Incorrect