Chapter 0 - Exercise 1 (f)

[leosol]

I think that there is no integer n such that n = n +1
By this, I think that Espsylon should be added as a comment to the actual solution.

[joao-vitor-souza]

I think that there is no integer n such that n = n +1 By this, I think that Espsylon should be added as a comment to the actual solution.

Actually, $\epsilon$ is used for empty strings. You probably meant that the solution would be the empty set, denotated by $\emptyset$. Notice that { $\epsilon$ } $\neq \emptyset$

[XingxinHE]

Agree. Maybe the answer is simply "an empty set".