Which one of the following regular expressions is NOT equivalent to the regular expression (a + b + c) *?
(A) (a* + b* + c*)*
(B) (a*b*c*)*
(C) ((ab)* + c*)*
(D) (a*b* + c*)*
Answer: (C)
Explanation: C– (ab)* + c*)* will always give strings with “ab” together.Whereas (a+b+c)* would generate language where a,b,c may not be always together.
A,B,D may generate same language as (a+b+c)*
So, Answer is (C)
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