- Option : D
- Explanation :

d(AB) = d(A) × d(B)

d(A + B) ≥ d(A) + d(B)

r(A + B) ≤ r(A) + r(B)

r(AB) ≠ r(A) r(B)

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- Option : A
- Explanation :

To find a number between range [x, y] requires log n comparisons.

As, K numbers are to be found, K + log n would be time complexity.

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39. Consider a schedule of transactions T_{1} and T_{2}:

T_{1} | RA | RC | WD | WB | Commit | |||||

T_{2} | RB | WB | RD | WC | Commit |

- Option : D
- Explanation :

R_{2}(B) is conflicting with W_{1}(B) so, W_{1}(B) should always come after R_{2}(B)

W_{2}(B) is conflicting with W_{1}(B) similarly, W_{1}(B) should always come after W_{2}(B)

R_{2}(D) is conflicting with W_{1}(D), so, W_{1}(D) should always come after R_{2}(D)

R_{1}(C) is conflicting with W_{2}(C) so, W_{2}(C) should always come after R_{1}(C)

Therefore the transaction will be:T1 T2 R(B) W(B) R(D) R(A) R(C) W(D) W(B) W(C) Commit Commit

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- A
A cell in R holds a set instead of an atomic value.

- B
R has a non-trivial functional dependency X → A, where X is not a superkey and A is a prime attribute

- C
R has a non-trivial functional dependency X → A, where X is not a superkey and A is a non-prime attribute and X is a proper subset of some key.

- D
R has a non-trivial functional dependency X → A, where X is not a superkey and A is a non-prime attribute and X is not a proper subset of any key.

- Option : B
- Explanation :

R has a nontrivial functional dependency X → A where X is not a sup and A is a prime attribute.

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