# 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) Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. nirosa1234@gmail.com said: (1:02am on Sunday 25th August 2013) it is not regular so it is context free only Write your comments here:
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 Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. Nancy said: (6:48am on Thursday 15th August 2013) L is regular and R is Context free which is not regular. Regular U CFG => Regular Write your comments here:
23:

FSM can recognize

 A. any grammar B. only CG C. Both (a) and ( b ) D. only regular grammar Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Write your comments here:
24:

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

 A. union B. complementation C. intersection D. All of these Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. gunjan said: (5:51pm on Tuesday 22nd October 2013) regular languages are closed under union,intersection. kl said: (4:50pm on Tuesday 12th November 2013) i have read closer properties of regular language.these are union,intersection complement ,homomorphic,kleen closer soumyasubeesh said: (3:04am on Friday 15th May 2015) the question is about not closed. but all options are closed properties. Write your comments here:
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) Answer Report Discuss 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'. Click on Discuss to view users comments. anita said: (5:09pm on Tuesday 2nd May 2017) option a should be also correct because all language can not be come into cfg Write your comments here:

X