# Recent questions tagged regular-expressions

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There are two sources on YouTube giving different answers for the same expression.I am confused. Is the given expressions wxwr | w,x $\in$(0,1)+ I think this is regular because this can be reduced to ending with 00 or 01 or 10 or 11 wwrx | w,x $\in$(0,1)+ I think this is regular because it can reduced to starting with 0 or 1
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Let l={ (ap )* | p is a prime number} and $\sum$={a}.The minimum number of states in NFA which can accept this language. This is a question from a test series,I just want to know if the question is valid as I feel raised to prime number will not be regular,correct me if I am wrong.Not asking for solution to the question but if the question is valid.
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Which is the equivalent Regular Expression for the following: "Strings in which every group of 3 symbols should contain atleast 1 a." a)[(a+b) (a+b)a]* b) [(a+b) (a+b)a]* [(a+b)(a+b)a]* c)[(ϵ + b + bb)a]* [ ϵ+ b + bb] d) (abb)* (bab)b* (bba)*
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Can you please draw the DFA for given regex (ab*)*
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For $\sum$={a,b} Re given is b*ab*(aa)*b* this is non minimized dfa but when the dfa is minimized we get RE as b*a(a+b)*. How to show that are they equivalent or is it just worked for this case?
1 vote
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what is the equivalent nfa for the given regular expression? a*b*(ba)*a*
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Not able to construct the regular expressions for the statements
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difference between a*(ba)* and (a+ba)* and how to represent both in finite automata?
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how can we represent (ab)*ba*(b+a)*aab* in finite automata?
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Why is WXWR a regular language but XWWR is not? (X,W ϵ (0,1)+)
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Why is ambn / m,n>=1 a regular language but anbn / n>=1 not?
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Find regular expressions for the following languages on {a, b}. (a) L = {w : |w| mod 3 = 0} (b) L = {w : na (w)mod 3 = 0} (c) L = {w : na (w)mod 5 > 0} Also Design DFA for the same.
1 vote
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Given two Regular expressions are equal or not ? 1) (1+01*0)* 2) 1*(01*0)* 1* Give proper explanation also.
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Let L be a regular language over $\{0,1\}$. Define the reverse of the language $L$ to be the language $L^R = \{ w \in \{0,1\}^* \: \: : \: \: \text{ reverse }(w) \in L\}$, where $\text{reverse}(w)$ denotes the string $w$ ... $x$ contains an odd number of $1's$ and $00$ as a substring$\}.$ Construct a regular expression for the language $L$.
1 vote
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Consider the following regular expression R=(a+b)* (a+b+ε)a which of the following is equivalent to the above a)(a*+b*)+ (aa+ba) b)(ε+a+b*)+ a c)(a+b)+ (a+b+ε)a d)None of these
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Is the given Grammer represent a regular language ? S->AaB A->aC | epsilon B->aB | bB | epsilon C->aCb | epsilon
1 vote
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Consider the regular expression R = a*b* + b*a*. The number of equivalence classes of Σ* to represent a language which is equivalent to R is ____________.
1 vote
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Is Language L = {0(n+m) 1(k+l) | m = l, and m,n,k,l ≥ 1 } a regular language ? explain
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can i get all the formulas of expression (a+b)*.
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Consider this regular expression: r = (a*b)* + (b*a)* This is equivalent to (a) (a + b)* (b) (a + b)* · (ab)+ + (a + b)* (ba)+ (c) (a + b)*a + (a + b)* b (d) None of above
1 vote
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Ans. D
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Ans. C
1 vote
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Ans. B
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How to construct a finite automata equivalent to the regular expression: ( 0 + 1 )* ( 00 + 11 ) ( 0 + 1 )*
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Which of the following CFG’s can’t be simulated by an FSM ? a. S->Sa/b b. S->aSb/ab c. S->abX, X->cY, Y->d/aX d. None of these