Question 21 : Regular expression x/y denotes the set
1. {x,y}
2. {xy}
3. {x}
4. {y}
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Question 22 : Regular expression (x/y)(x/y) denotes the set
1. {xy,xy}
2. {xx,xy,yx,yy}
3. {x,y}
4. {x,y,xy}
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Question 23 : The production Grammar is {S->aSbb, S->abb} is
1. type-3 grammar
2. type-2 grammar
3. type-1 grammar
4. type-0 grammar
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Question 24 : Give a production grammar for the language L = {x/x ? (a,b)*, the number of a's in x is multiple of 3}.
1. {S->bS, S->b,S->aA, S->bA, A->aB, B->bB, B->aS, S->a}
2. {S->aS,S->bA,A->bB,B->bBa,B->bB}
3. {S->aaS,S->bbA,A->bB,B->ba}
4. None of the mentioned
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Question 25 : Let R1 and R2 be regular sets defined over alphabet ? then
1. R1 UNION R2 is regular
2. R1 INTERSECTION R2 is regular
3. ? INTERSECTION R2 IS NOT REGULAR
4. R2* IS NOT REGULAR
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Question 26 : Consider the production of the grammar S->AA A->aa A->bb Describe the language specified by the production grammar.
1. L = {aaaa,aabb,bbaa,bbbb}
2. L = {abab,abaa,aaab,baaa}
3. L = {aaab,baba,bbaa,bbbb}
4. L = {aaaa,abab,bbaa,aaab}
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Question 27 : Regular expressions are closed under
1. Union
2. Intersection
3. Kleene star
4. All of the mentioned
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Question 28 : L and ~L are recursive enumerable then L is
1. Regular
2. Context free
3. Context sensitive
4. Recursive
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Question 29 : Regular expression are
1. Type 0 language
2. Type 1 language
3. Type 2 language
4. Type 3 language
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Question 30 : Which of the following is not a regular expression?
1. [(a+
2. *-(aa+bb)]*b) [(0+1)-(0b+a1)*(a+b)]*
3. (01+11+10)*
4. (1+2+0)*(1+2)*
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