0 votes 0 votes What is the class of the language resulting from Union of R.E and non R.E ? (R.E => recursively enumerable) Theory of Computation theory-of-computation recursive-and-recursively-enumerable-languages + – Xylene asked Jun 17, 2017 • retagged Jul 4, 2017 by Arjun Xylene 1.2k views answer comment Share Follow See all 2 Comments See all 2 2 Comments reply Hemant Parihar commented Jun 18, 2017 reply Follow Share Non Recursive enumerable language. 1 votes 1 votes Xylene commented Jun 18, 2017 reply Follow Share Any source or link ? 0 votes 0 votes Please log in or register to add a comment.
1 votes 1 votes Non-RE language can be anything... So we union it with RE language....there is no possibility that we can get only RE language... So answer is Non-R.E language bad_engineer answered Jun 18, 2017 bad_engineer comment Share Follow See all 2 Comments See all 2 2 Comments reply Xylene commented Jun 18, 2017 reply Follow Share Thanks for your reply. In this question https://gateoverflow.in/355/gate2003-54 , first one is R.E and second one is not R.E. So their union(L=L1 U L2) is not R.E . Can we apply this logic over there? Complement of R.E is undecidable so we can't say whether it's complement is R.E or not ? Right? 0 votes 0 votes bad_engineer commented Jun 18, 2017 reply Follow Share RE is not closed under complement so we can never be sure its complement may or may not be RE 0 votes 0 votes Please log in or register to add a comment.
