Compilers

Context Free Grammar

Question 1
Marks : +2 | -2
Pass Ratio : 100%
The context free grammar S → A111|S1, A → A0 | 00 is equivalent to _________
{0n1m | n=2, m=3}
{0n1m | n=1, m=5}
{0n1m | n should be greater than two and m should be greater than four}
None of the mentioned
Explanation:
S-> A111
Question 2
Marks : +2 | -2
Pass Ratio : 100%
Grammars that can be translated to DFAs is ___________
Left linear grammar
Right linear grammar
Generic grammar
All of the mentioned
Explanation:
Right linear grammar can be translated to the DFAs.
Question 3
Marks : +2 | -2
Pass Ratio : 100%
A CFG is closed under _________
Union
Kleene star
Concatenation
None of the mentioned
Explanation:
CFG is closed under the above mentioned 3 operations.
Question 4
Marks : +2 | -2
Pass Ratio : 100%
Assume the statements S1 and S2 given as:
S1 is correct and S2 is not correct
Both S1 and S2 are correct
Both S1 and S2 are not correct
S1 is not correct and S2 is correct
Explanation:
The proof of S1 can be seen in various book of theory of computation but s2 is a problem of category undecidable so a contradiction to this assumption can be easily obtained.
Question 5
Marks : +2 | -2
Pass Ratio : 100%
The context free grammar S → SS | 0S1 | 1S0 | ɛ generates _________
Equal number of 0’s and 1’s
Unequal number of 0’s and 1’s
Number of 0’s followed by any number of 1’s
None of the mentioned
Explanation:
S->SS
Question 6
Marks : +2 | -2
Pass Ratio : 100%
Which of these does not belong to CFG?
Terminal Symbol
Non terminal Symbol
Start symbol
End Symbol
Explanation:
CFG consists of terminal non terminal start symbol set of production rules but does not have an end symbol.
Question 7
Marks : +2 | -2
Pass Ratio : 100%
Recursively enumerable languages are not closed under ______________
Union
Intersection
Complementation
Concatenation
Explanation:
Recursive languages are closed under the following operations.
Question 8
Marks : +2 | -2
Pass Ratio : 100%
Grammar that produce more than one Parse tree for same sentence is ___________
Ambiguous
Unambiguous
Complementation
Concatenation Intersection
Explanation:
An ambiguous grammar is one for which there is more than one parse tree for a single sentence.
Question 9
Marks : +2 | -2
Pass Ratio : 100%
Which of the following conversion is not possible (algorithmically)?
Regular grammar to CFG
NDFA to DFA
NDPDA to DPDA
NDTM to DTM
Explanation:
Not every NDPDA has an equivalent deterministic PDA.
Question 10
Marks : +2 | -2
Pass Ratio : 100%
If P & R are regular and also given that if PQ=R, then?
Q has to be regular
Q cannot be regular
Q need not be regular
Q has to be a CFL
Explanation:
If two regular languages when combined do not always produce a regular language.