Classical

Theory Of Computation MCQ - Context free languages

41:  

 Context free grammar is not closed under

A.

product

B.

union

C.

complementation 

D.

kleen star

 
 

Option: C

Explanation :


42:  

 If L be a language recognizable by a finite automaton, then language front

{L} = { w such that w is prefix of v where v ∈ L },  is a

A.

regular language

B.

context-free language

C.

context-sensitive language

D.

recursive enumeration language

 
 

Option: A

Explanation :


43:  

 For which of the following application, regular expressions can not be used ?

A.

Designing computers

B.

Designing compilers 

C.

Both (a) and (b)

D.

Developing computers

 
 

Option: C

Explanation :

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44:  

Consider the following grammar

                                   S --> Ax / By
                                   A --> By/Cw
                                    B --> x / Bw
                                    C--> y


Which of the regular expressions describe the same set of strings as the grammar ?

A.

xw * y + xw * yx + ywx

B.

xwy + xw * xy + ywx

C.

xw * y + xw x yx + ywx

D.

xw xy + xww * y + ywx

 
 

Option: A

Explanation :


45:  

 Which of the following statements is (are) correct ?

A.

Recursive languages are closed under complementation.

B.

If a language and its complement are both regular, the language is recursive

C.

Set of recursively enumerable language is closed under union

D.

 All of these

 
 

Option: D

Explanation :




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