Q. Which of the following is called Bar-Hillel lemma?

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Q. Which of the expressions correctly is an requirement of the pumping lemma for the context free languages?

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Q. Let L be a CFL. Then there is an integer n so that for any u that belong to language L satisfying
|t|>=n, there are strings u, v, w, x, y and z satisfying

t=uvwxy.

Let p be the number of variables in CNF form of the context free grammar. The value of n in terms of p :

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Q. Which of the following gives a positive result to the pumping lemma restrictions and requirements?

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Q. Using pumping lemma, which of the following cannot be proved as ‘not a CFL’?

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Q. State true or false:
Statement: We cannot use Ogden’s lemma when pumping lemma fails.

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Q. Which of the following cannot be filled in the blank below?
Statement: There are CFLs L1 nad L2 so that ___________is not a CFL.

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Q. The pumping lemma is often used to prove that a language is:

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Q. What is the pumping length of string of length x?

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Q. Which of the following does not obey pumping lemma for context free languages ?

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Q. The context free languages are closed under:

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Q. Given Grammar G1:
S->aSb

S->e

Grammar G2:

R->cRd

R->e

If L(G)=L(G1) U L(G2), the number of productions the new starting variable would have:

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Q. Context free languages are not closed under:

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Q. Which of the following is incorrect?
There exists algorithms to decide if:

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Q. If the start symbol is one of those symbols which produce no terminal through any sequence, the CFL is said to be

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Q. Using the pumping constant n, If there is a string in the language of length between _____ and ____ then the language is infite else not.

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Q. Which of the following is/are CFL not closed under?

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Q. If L1 and L2 are context free languages, L1-L2 are context free:

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Q. A___________ is context free grammar with atmost one non terminal in the right handside of the production.

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Q. There is a linear grammar that generates a context free grammar

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