# How to show {n:U(n,x) is defined for all x} is not enumerable [duplicate]

U(n,x) is Gödel universal function, and we need to show {n:U(n,x) is defined for all x} is not enumerable. I do not have any clue right now. Anyone can give me some hint about this question.

• Welcome to Computer Science! Note that you can use LaTeX here to typeset mathematics in a more readable way. See here for a short introduction. – FrankW Oct 11 '14 at 10:36
• Hint: Rice's theorem. – FrankW Oct 11 '14 at 10:36
• I still can not get it... – w66162906 Oct 12 '14 at 11:31
• – Ran G. Jun 3 '15 at 22:12