For relation R = (L, M, N, O, P), the following dependencies hold: { M → O, NO…

For relation R = (L, M, N, O, P), the following dependencies hold: { M → O, NO → P, P → L, L → MN }. R is decomposed into R1 = (L, M, N, P) and R2 = (M, O). The decomposition is:

Answer: B. Lossless decomposition and not dependency preservingConclusion: The decomposition is lossless and not dependency preserving. Lossless-join check: The intersection of the two decomposed schemas (L,M,N,P) and…

  1. A.

    Lossless decomposition and dependency preserving

  2. B.

    Lossless decomposition and not dependency preserving

  3. C.

    Lossy decomposition and dependency preserving

  4. D.

    Lossy decomposition and not dependency preserving

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Correct answer: B

Conclusion: The decomposition is lossless and not dependency preserving.

  • Lossless-join check: The intersection of the two decomposed schemas (L,M,N,P) and (M,O) is {M}. Because the FD M → O is in the given set, M functionally determines both attributes of the second relation (M,O). Therefore the intersection functionally determines one of the relations, which satisfies the lossless-join condition. Hence the decomposition is lossless.

  • Dependency preservation check: The original FDs are M → O, NO → P, P → L, and L → MN. Projecting these onto the decomposed relations gives:

    • Onto (L, M, N, P): P → L and L → MN.

    • Onto (M, O): M → O.

    The FD NO → P involves attributes from both relations (N and O on one side, P on the other) and is not present in either projection. It also cannot be derived from the projected FDs: using the projected FDs, the closure of {N,O} is only {N,O}, so P is not implied. Therefore NO → P is not preserved, and the decomposition is not dependency preserving.

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