Which of the following functional dependencies are satisfied by the instance?
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Which of the following functional dependencies are satisfied by the instance?
- A.
XY → Z and Z → Y
- B.
YZ → X and Y → Z
- C.
YZ → X and X → Z
- D.
XZ → Y and Y → X
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Correct answer: B
Check each dependency using the table.
YZ → X:
No two tuples have the same (Y, Z) with different X ⇒ satisfied.X → Z:
For X = 1, Z values are 2 and 3 ⇒ not satisfied.Y → Z:
All Y values are distinct ⇒ satisfied.Z → Y:
Z = 2 corresponds to Y = 4 and Y = 2 ⇒ not satisfied.
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