Classical

Theory Of Computation MCQ - Context free languages

21:  

L = (an bn an | n = 1,2,3)  is an example of a language that is

A. context free
B. not context free
C. not context free but whose complement is CF
D. both (b) and (c)
 
 

Option: D

Explanation :

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nirosa1234@gmail.com said: (8:02am on Sunday 25th August 2013)
it is not regular so it is context free only

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22:  

If Σ = (0, 1), L = Σ* and R = (0n 1nsuch that  n >  0 )

then languages L ∪ R and R respectively are

A.

Regular, Regular

B.

Regular, Not regular

C.

Not regular, Not regular

D.

None of these

 
 

Option: B

Explanation :

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Nancy said: (1:48pm on Thursday 15th August 2013)
L is regular and R is Context free which is not regular. Regular U CFG => Regular

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23:  

 FSM can recognize

A. any grammar
B. only CG
C. Both (a) and ( b )
D. only regular grammar
 
 

Option: D

Explanation :

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24:  

 Set of regular languages over a given alphabet set is not closed under

A. union
B. complementation
C. intersection
D. All of these
 
 

Option: D

Explanation :

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gunjan said: (12:51am on Wednesday 23rd October 2013)
regular languages are closed under union,intersection.
kl said: (11:50pm on Tuesday 12th November 2013)
i have read closer properties of regular language.these are union,intersection complement ,homomorphic,kleen closer
soumyasubeesh said: (10:04am on Friday 15th May 2015)
the question is about not closed. but all options are closed properties.

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25:  

Which of the following statement is correct?

A.

All languages can not be generated by CFG

B.

Any regular language has an equivalent CFG

C.

Some non regular languages can't be generated by CFG

D.

both (b) and (c)

 
 

Option: D

Explanation :

CFG is a higher than regular language. So we can draw a regular equivalent to CFG. And some non regular like context sensitive can't be generated by cfg. So, option 3  and 2 are correct. So answer is 'D'.

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anita said: (12:09am on Wednesday 3rd May 2017)
option a should be also correct because all language can not be come into cfg

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