Let r be a rational instance with schema R = (A, B, C, D). We define r1 = A, B, C(r) and r2 = A, D(r). Let s = r1 * r2 where * denotes natural join. Given that the decomposition of r into r1 and r2 is lossy, which one of the following is true?

Let r be a rational instance with schema R = (A, B, C, D). We define r

1.	Let r be a rational instance with schema R = (A, B, C, D). We define r₁ = _{A, B, C}(r) and r₂ = _{A, D}(r). Let s = r₁ * r₂ where * denotes natural join. Given that the decomposition of r into r₁ and r₂ is lossy, which one of the following is true?
A.	s r
B.	r s = r
C.	r s
D.	r * s = s
Answer» D. r * s = s

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Let r be a rational instance with schema R = (A, B, C, D). We define r1 = A, B, C(r) and r2 = A, D(r). Let s = r1 * r2 where * denotes natural join. Given that the decomposition of r into r1 and r2 is lossy, which one of the following is true?

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Let r be a rational instance with schema R = (A, B, C, D). We define r₁ = _{A, B, C}(r) and r₂ = _{A, D}(r). Let s = r₁ * r₂ where * denotes natural join. Given that the decomposition of r into r₁ and r₂ is lossy, which one of the following is true?