2 votes 2 votes I totally understand the Halting problem, what about complement of halting problem? Is this the set of all those language which never halts? Why complement of halting problem is not re? Proof plz Theory of Computation theory-of-computation turing-machine + – Na462 asked Jan 21, 2018 Na462 1.4k views answer comment Share Follow See 1 comment See all 1 1 comment reply nadeshseen commented Nov 9, 2019 reply Follow Share halting problem is recursively enumerable, therefore its complement will be NOT RE. NOT RE = Languages in which TM will never halt on atleast one string that is in the language. 0 votes 0 votes Please log in or register to add a comment.