COM S 461: ASSIGNMENT 2 solution

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Objectives:
1. Exercise your understanding of functional dependencies and normalization
Questions:
1. (20 points): Suppose that we have the following three tuples in a legal instance
of a relation schema S with three attributes ABC (listed in order):
(1, 2, 3), (4, 2, 3), and (5, 3, 3).
• Which of the following dependencies can you infer does not hold over
schema S?
AB, BCA, BC
• Can you identify any dependencies that hold over S?
2. (20 points): Consider the attribute set R={A, B, C, D, E, G} with the set of
dependencies F = {ABC, ACB, ADE, BD, BCA, EG}. Answer the
following questions (you must explain why):
• Is D1 = {ABC, ACDE, ADG} a lossless join decomposition?
• Is D1 a dependency-preserving decomposition?
• What is the strongest normal form of ABC and why?
3. (20 points): Consider a relation R with the attribute set {A, B, C, D, E, F, G, H, I, J} and a
corresponding set of functional dependencies F = {ABC, ADE, BF, FGH, DIJ}.
Given the following decomposition:
D2 = {R1, R2, R3, R4, R5}
R1 = {A, B, C, D}
R2 = {D, E}
R3 = {B, F}
R4 = {F, G, H}
R5 = {D, I, J}
• Is D2 a dependency-preserving decomposition? Why?
• Is D2 a lossless-join decomposition? Why?
Submission Requirements:
1. Put your answers in a Word document, and email it to the TA and cc to the instructor.