0 votes 0 votes Find the regular expression No 2 a's and 2 b's should come together? Theory of Computation theory-of-computation + – gabbar asked Feb 19, 2017 gabbar 3.6k views answer comment Share Follow See all 10 Comments See all 10 10 Comments reply Devshree Dubey commented Feb 19, 2017 reply Follow Share Is d answer (ab)^*+(ba)^*??? 0 votes 0 votes gabbar commented Feb 19, 2017 reply Follow Share (epsilon+b) (ab) *(a+epsilon) 0 votes 0 votes Devshree Dubey commented Feb 19, 2017 reply Follow Share epsilon symbol would hold for NULL. Isn't it? 0 votes 0 votes Devshree Dubey commented Feb 19, 2017 reply Follow Share And why not ba??. Coz it says No 2a's and no 2b's should be together. The minimum possible symbols acceptable are a,b,ab,ba. Isn't it? 0 votes 0 votes Devshree Dubey commented Feb 19, 2017 reply Follow Share Why don't u try to cover d basic?? Unlike start with the fundamentals of R.E. For dat ur Engineering Textbook on TOC is more den enough. Always grasp d concept den hit at d question. Yeah!!!. Lectures of IIT Profs especially dat of Mam Kamla Krithivasan must refer. K. Hope dat it helps u. :) https://www.youtube.com/watch?v=-aIRqNnUvEg&list=PL85CF9F4A047C7BF7 0 votes 0 votes gabbar commented Feb 19, 2017 reply Follow Share In your case devshree, there can be many cases with different symbol...and the question here is no 2 consecutive a and no 2 consecutive b 's can comes together.. L={a, b, ab, ba, aba,bab, abab, baba.....,} isn't it 0 votes 0 votes Devshree Dubey commented Feb 19, 2017 reply Follow Share Yes. :) 0 votes 0 votes gabbar commented Feb 19, 2017 reply Follow Share Thnq for ur suggestion.:) . Really nptel course are so boring I have watched her video.but.for toc its better to watch shai simonson video rather than nptel.. :) 0 votes 0 votes Vivek Jain commented Feb 19, 2017 reply Follow Share it means select epsilon or b from the first part From the second part u can get any number of ab And from the third part u can select a or epsilon. 0 votes 0 votes Devshree Dubey commented Feb 19, 2017 reply Follow Share No probs. Work out d way u feel it's better. Yeah. :) 0 votes 0 votes Please log in or register to add a comment.
1 votes 1 votes No two a's and b's should come together..so language is L=(Epsilon+b)(ab)* (a+Epsilon). L={Epsilon, b, a, ab,abab,....,bab,babab,....aba,ababa,....} Vivek Jain answered Feb 19, 2017 Vivek Jain comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes (a+€) (ba) * (b+€) + a+b+ab+€ Explanation : The only possible strings is a followed by b and b followed by a tht is bababa..... So we get (ba) * But strings could also start with a and could also end with b So we add (€+a) and (b+€) at the start and the end But the minimum possible string in our regular expression is ba which means we have left some strings So we add ab+a+b+€ in the end to cover all possible strings bhargav9873 answered Feb 26, 2017 bhargav9873 comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes alphabets= { a , b } L={ epsilon , a , b , ab , ba , aba , bab , abab ,...........................} it's infinite language It may have these two answers 1) (epsilon+b)(ab)*(epsilon+a) or 2) (epsilon+a)(ba)*(epsilon+b) Both of them are correct shivam001 answered May 20, 2019 shivam001 comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes RE : (a+ba)(ba)* + (b+ab)(ab)* + ϵ tech_beardo answered Nov 25, 2019 tech_beardo comment Share Follow See all 0 reply Please log in or register to add a comment.