Compilers

Context Free Grammar

Question 1
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 2
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 3
Marks : +2 | -2
Pass Ratio : 100%
Push down automata accepts which language?
Context sensitive language
Context free language
Recursive language
None of the mentioned
Explanation:
PDA accepts CFG.
Question 4
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 5
Marks : +2 | -2
Pass Ratio : 100%
Given the following statements: (i) Recursive enumerable sets are closed under complementation. (ii) Recursive sets are closed under complements. Which is/are the correct statements?
I only
II only
Both I and II
Neither I nor II
Explanation:
Recursive languages are closed under the following operations.
Question 6
Marks : +2 | -2
Pass Ratio : 100%
Which of the following language accepted by a Push down Automata?
Type0
Type1
Type2
Type3
Explanation:
A known fact that type 2 grammar is accepted by PDA.
Question 7
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 8
Marks : +2 | -2
Pass Ratio : 100%
A regular Grammar is a _________
CFG
Non CFG
English Grammar
None of the mentioned
Explanation:
Regular grammar is CFG. It restricts its rules to a single non terminal on left hand side.
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%
A CFG is closed under _________
Union
Kleene star
Concatenation
None of the mentioned
Explanation:
CFG is closed under the above mentioned 3 operations.