Answer : Option CExplaination / Solution:
Option A is false since BCNF is stricter than 3NF (it needs LHS of all FDs should be candidate
key for 3NF condition)
Option B is false since the definition given here is of 2NF
Option C is true, since for a relation to be in BCNF it needs to be in 3NF, every relation in
BCNF satisfies all the properties of 3NF.
Option D is false, since if a relation is in BCNF it will always be in 3NF.
Q4.Suppose R1 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 constrains, which of the following is ALWAYS TRUE?
Answer : Option AExplaination / Solution: No Explaination.
2) If L is context-free language, then, is also context-free?
3) If L is regular language, then, is also regular?
4) If L is recursive language, then, is also recursive?
Answer : Option DExplaination / Solution:
CFL’s are not closed under complementation. Regular and recursive languages are closed
under complementation.
How many tuples does the result of the following SQL query contain?
SELECT A.Id
FROM A
WHERE A.Age > ALL(SELECT B.Age FROM B
WHERE B.Name = ‘Arun’)
Answer : Option BExplaination / Solution:
As the result of subquery is an empty table, ‘>ALL’ comparison is true . Therefore, all the
three row id’s of A will be selected from table A.
Q8.Given the language L-{ab, aa, baa}, which of the following strings are in L*?
1) abaabaaabaa
2) aaaabaaaa
3) baaaaabaaaab
4) baaaaabaa
Answer : Option CExplaination / Solution:
L ={ab, aa, baa}
Let S1 = ab , S2 = aa and S3 =baa
abaabaaabaa can be written as S1S2S3S1S2
aaaabaaaa can be written as S1S1S3S1
baaaaabaa can be written as S3S2S1S2
Q9.A process executes the code
fork ();
fork ();
fork ();
The total number of child processes created is
Answer : Option CExplaination / Solution:
If fork is called n times, there will be total 2n running processes including the parent process.
So, there will be 2n -1 child processes.