Q. If R is regular language and Q is any language (regular/ non regular), then Pref (Q in R) is ———.

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Q. Regular expression a/b denotes the set

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Q. In regular expressions, the operator ‘*’ stands for

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Q. Find the pair of regular expressions that are equivalent

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Q. Consider alphabet ∑ = {0, 1}, the null/empty string λ and the sets of strings X0, X1 and X0.How are X1 and X2 are related ?

X0 = 1 X1
X1 = 0 X1 + 1 X2
X2 = 0 X1 + {λ}

Which one of the following represents the strings in X0?

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Q. Which of the following pairs of regular expression are equivalent?

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Q. Which of the following identity is true?

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Q. The set of all strings over ∑ = {a,b} in which all strings having bbbb as substring is

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Q. The set of all strings over ∑ ={a,b} in which a single a is followed by any number of b’s a single b followed by any number of a’s is

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Q. Regular expressions are used to represent which language

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Q. The set of all strings over ∑ = {a,b} in which strings consisting a’s and b’s and ending with in bb is

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Q. If P, Q, R are three regular expressions and if P does not contain a then the equation R = R + RP has a unique solution given by

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Q. Which of the following regular expression denotes zero or more instances of an a or b?

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Q. The string (a)|((b)*(c)) is equivalent to

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Q. How many strings of length less than 4 contains the language described by the regular expression (x+y)*y(a+ab)* ?

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Q. Which of the following is true ?

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Q. Let the class of language accepted by finite state machine be L1 and the class of languages represented by regular expressions be L2 then

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Q. Which of the following is not a regular expression?

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Q. Regular expression are

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Q. Regular expressions are closed under

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