6 votes 6 votes Which of the following pairs of regular expression are not equivalent? A. (a*+b)* and (a+b)* B. (ab)*a and a(ba)* C. (a+b)* and (a*b*)*b* D. none of the above Theory of Computation regular-expression + – 1gate_cracker asked Nov 11, 2017 1gate_cracker 3.6k views answer comment Share Follow See 1 comment See all 1 1 comment reply joshi_nitish commented Nov 11, 2017 reply Follow Share option D. since all the pairs in A, B, C are equivalent. 0 votes 0 votes Please log in or register to add a comment.
1 votes 1 votes All pairs are similar Hence Option D is correct Ashwin Kulkarni answered Nov 11, 2017 Ashwin Kulkarni comment Share Follow See all 3 Comments See all 3 3 Comments reply akshat sinha commented Dec 31, 2017 reply Follow Share how C is true? 0 votes 0 votes pranab ray commented Dec 31, 2017 reply Follow Share c is true (a+b)* and (a*b*)*b* (a*b*)*b*={epslone,a,aa,aaa,aaa......,b,bb,bbb,bbbb.....,ab,abab,......now "ba" sequence also we can produce by (a*b*)^2=(a*b*)(a*b*)=(a^0b)(ab^0)=ba like that baba,bababa......}=(a+b)* 0 votes 0 votes akshat sinha commented Dec 31, 2017 reply Follow Share isn't it is same as (a*b*)* only. I mean (a*+b*)* = (a*b*)* = (a*b*)*b* ? Please correct me if I am wrong 0 votes 0 votes Please log in or register to add a comment.