Normalization concept check — does Fifth Normal Form (5NF) isolate multivalued dependencies?\nEvaluate the statement: “A relation is in 5NF when multivalued dependencies are isolated in their own relation.” Decide if this is correct or incorrect.

Introduction / Context:
Normal forms help reduce redundancy and anomalies by constraining functional and other dependencies. The question distinguishes between Fourth Normal Form (4NF) and Fifth Normal Form (5NF, also called Project-Join Normal Form, PJ/NF).

Given Data / Assumptions:

• We consider lossless decomposition and dependency preservation principles.
• Multivalued dependencies (MVDs) are a generalization of functional dependencies describing independent attribute sets.
• Join dependencies (JDs) extend the idea of constraints that require a relation to equal the join of its projections.

Concept / Approach:
4NF eliminates nontrivial multivalued dependencies (X ↠ Y) that are not implied by a candidate key; to achieve 4NF, relations with problematic MVDs are decomposed so each independent multi-valued attribute set resides separately. 5NF goes further: it ensures that every nontrivial join dependency is implied by the candidate keys. In other words, 5NF eliminates redundancy arising only reconstructible through lossless joins of three or more projections, not merely those from MVDs.

Step-by-Step Solution:

Verification / Alternative check:
Standard texts: 3NF/BCNF handle FDs; 4NF handles MVDs; 5NF (PJ/NF) handles JDs where redundancy appears only when three or more tables are joined.

Why Other Options Are Wrong:

• “Correct — 5NF addresses MVDs” is precisely the confusion.
• “Correct only when there are no candidate keys” and “Depends on the DBMS” are unrelated to the theoretical definitions.
• “3NF handles MVDs” is false; 3NF addresses FDs and transitive dependencies.

Common Pitfalls:
Equating MVDs with JDs; assuming higher normal forms always supersede earlier ones in a single dependency type.

Final Answer:
Incorrect — 4NF addresses multivalued dependencies; 5NF addresses join dependencies