1
GATE CSE 2012
MCQ (Single Correct Answer)
+2
-0.6
Consider the following relations A, B and C:
A
ID Name Age
12 Arun 60
15 Shreya 24
99 Rohit 11

B
ID Name Age
15 Shreya 24
25 Hari 40
98 Rohit 20
99 Rohit 11

C
ID Phone Area
10 2200 02
99 2100 01

How many tuples does the result of the following relational algebra expression contain? Assume that the schema of A ∪ B is the same as that of A. $$(A\cup B)\bowtie _{A.Id > 40 \vee C.Id < 15} C$$

A
7
B
4
C
5
D
9
2
GATE CSE 2012
MCQ (Single Correct Answer)
+2
-0.6
Suppose R1 (A, B) and R2 (C, D) are two relation schemas. Let r1 and r2 be the corresponding relation instances. B is a foreign key that refers to C in R2. If data in r1 and r2 satisfy referential integrity constraints, which of the following is ALWAYS TRUE?
A
$$\prod_{B}(r_{1})- \prod _{C}(r_{2})= \varnothing$$
B
$$\prod_{C}(r_{2})- \prod _{B}(r_{1})= \varnothing$$
C
$$\prod_{B}(r_{1}) = \prod _{C}(r_{2})$$
D
$$\prod_{B}(r_{1}) - \prod _{C}(r_{2}) \neq \varnothing$$
3
GATE CSE 2012
MCQ (Single Correct Answer)
+2
-0.6
Consider the following transactions with data items P and Q initialized to zero:
T1 : read (P) ; 
     read (Q) ; 
     if P = 0 then Q : = Q + 1 ; 
     write (Q). 
T2 : read (Q) ; 
     read (P) 
     if Q = 0 then P : = P + 1 ; 
     write (P).
Any non-serial interleaving of T1 and T2 for concurrent execution leads to
A
a serializable schedule
B
a schedule that is not conflict serializable
C
a conflict serializable schedule
D
a schedule for which precedence graph cannot be drawn
4
GATE CSE 2012
MCQ (Single Correct Answer)
+2
-0.6
What is the minimal form of the Karnaugh map shown below? Assume that $$X$$ denotes a don’t care term. GATE CSE 2012 Digital Logic - K Maps Question 4 English
A
$$\overline {bd} $$
B
$$\overline {bd} + \overline {bc} $$
C
$$\overline {bd} + a\overline {bc} d$$
D
$$\overline {bd} + \overline {bc} + \overline {cd} $$
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