GATE PYQ

GATE CSE 1999

Q21.
Let R = (A, B, C, D, E, F) be a relation scheme with the following dependencies C \rightarrow F, E \rightarrow A, EC \rightarrow D, A \rightarrow B. Which one of the following is a key for R?

Q22.
The number of binary relations on a set with n elements is:

Q23.
Let L be a set with a relation R which is transitive, anti-symmetric and reflexive and for any two elements a, b \in L, let the least upper bound lub (a, b) and the greatest lower bound glb (a, b) exist. Which of the following is/are true?

Q24.
Raid configurations of the disks are used to provide

Q25.
A sorting technique is called stable if

Q26.
If one uses straight two-way merge sort algorithm to sort the following elements in ascending order: 20, 47, 15, 8, 9, 4, 40, 30, 12, 17 then the order of these elements after second pass of the algorithm is:

Q27.
System calls are usually invoked by using

Q28.
For the schedule given below, which of the following is correct:\begin{array}{lll} \text{1} & \text{Read A} & \text{} \\ \text{2} & \text{} & \text{Read B} \\ \text{3} & \text{Write A} & \text{} \\ \text{4} & \text{} & \text{Read A} \\ \text{5} & \text{} & \text{Write A} \\ \text{6} & \text{} & \text{Write B} \\ \text{7} & \text{Read B} & \text{} \\ \text{8} & \text{Write B} & \text{} \\\end{array}

Q29.
The relational algebra expression equivalent to the following tuple calculus expression: \left\{t \mid t \in r \land \left(t[A] = 10 \land t[B]=20\right)\right\} is