Q. Let G be a grammar: S->AB|e, A->a, B->b
Is the given grammar in CNF?

View solution

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

View solution

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

View solution

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 :

View solution

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

View solution

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

View solution

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

View solution

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.

View solution

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

View solution

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

View solution

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

View solution

Q. The context free languages are closed under:

View solution

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:

View solution

Q. Context free languages are not closed under:

View solution

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

View solution

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

View solution

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.

View solution

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

View solution

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

View solution

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

View solution