GATE CS 2002 Q1.19 — Normal Forms

A relation schema $R$ is in Boyce-Codd Normal Form (BCNF) if, for every non-trivial functional dependency $X \rightarrow Y$ in $F^+$, $X$ is a superkey of $R$.

Redundancy arising out of functional dependencies occurs when a non-trivial functional dependency $X \rightarrow Y$ exists where $X$ is not a superkey. In such a scenario, multiple tuples can share the same value for $X$, which forces them to also share the same value for $Y$, leading to repetitive (redundant) data storage.

Because BCNF strictly prohibits any non-trivial functional dependency where the left-hand side is not a superkey:

• No such FD-based redundancy can exist in any of the decomposed relations.
• Therefore, the redundancy arising specifically out of functional dependencies in a BCNF decomposition is zero.

Hence, the correct option is A.