Finite languages $L\in RE$ I want to check if I understood it in the right way.
In some example where $L\in RE$ the explanation deal with 2 cases: 1st when $L$ finite and 2nd when $L$ infinite. In the second case $L\in R$, isn't? Is it possible somehow that $L\in RE\setminus R$ be finite?
The answer is no. Every finite language is regular, and thus decidable. Therefore the existence of a finite language $L$ in $ \text{RE} \setminus \text{R}$ is impossible. However, note that there languages $L$ in $\text{RE}\setminus \text{R}$ (e.g., $Halt_{TM}$), and by what we have seen previously, such languages have to be infinite.