2 votes 2 votes is the language L={a^nb^n : n>=1} U {b} deterministic Meenakshi Sharma asked Aug 17, 2017 Meenakshi Sharma 2.3k views answer comment Share Follow See 1 comment See all 1 1 comment reply stblue commented Aug 17, 2017 i edited by Arjun Aug 17, 2017 reply Follow Share @akash.dinkar12 union of two dcfl need not be dcfl.. L={$a^{n}b^{n}$: n>=1} U {b} , Here we can deterministically determine string is belong to which part of union by looking at first symbol, if first alphabet is 'a' we will looking for string in the form $a^{n}b^{n}$, else if first alphabet is 'b' we are looking for b only, if anything comes after b we reject the string. So here we are able to deterministically determine that string is accepted or not, thats why its DCFL 11 votes 11 votes Please log in or register to add a comment.