Are “multiple (n-ary) relationships” and “binary relationships” the same concept in ER modeling, or do they differ by degree (number of participating entity types)?

Introduction / Context:
Understanding relationship degree prevents mistakes when modeling constraints. Binary relationships involve two entity types; multiple (n-ary) relationships involve three or more. Treating them as the same obscures important semantics, especially participation constraints and dependencies.

Given Data / Assumptions:

• Binary: exactly two entity types.
• N-ary (e.g., ternary): three or more entity types simultaneously related.
• We are discussing conceptual ER modeling, not just physical implementation.

Concept / Approach:
Although some ternary relationships can be decomposed into multiple binary relationships for implementation, this decomposition may lose the intended constraint that all three participants are related in a single fact (e.g., Supplier supplies Part to Project). Therefore, binary and n-ary are not the same at the conceptual level.

Step-by-Step Solution:

Verification / Alternative check:
Examine classic ER examples where ternary cannot be faithfully represented by three binaries without additional constraints.

Why Other Options Are Wrong:

• Correct/“equivalent after normalization” miss conceptual differences.
• Notation choice does not change meaning; it changes drawing style only.

Common Pitfalls:
Decomposing a ternary into binaries and assuming semantics are preserved; forgetting intersection table keys must capture all participants to maintain uniqueness.

Final Answer:
Incorrect