0 votes 0 votes Gate Fever asked Oct 13, 2018 Gate Fever 204 views answer comment Share Follow See all 3 Comments See all 3 3 Comments reply Utkarsh Joshi commented Oct 13, 2018 reply Follow Share if L2=sigma* then L4 will be regular so yes its possible that L4 is regular. 0 votes 0 votes Gate Fever commented Oct 15, 2018 reply Follow Share Utkarsh Joshi pls check this L4=L1.L2.L3 this means strings accepted by L1 concatenated by string accepted by L2 and then concatenated by string accepted by L2 right. if L1= anbn L2=sigma* L3=wwR; w belongs to (u,v)+ then can we say L4 is regular?? pls tell me this ;i am confused now!! 0 votes 0 votes Utkarsh Joshi commented Oct 15, 2018 reply Follow Share You can say it as regular if you allow n>=0 in a^nb^n and WW^r, |w|>=0. By doing so u can always generate any strings in sigma* assuming other two non regular languages as epsilon. 0 votes 0 votes Please log in or register to add a comment.