Software can be proven correct, but if you want to do anything useful with a computer system, you need more than just an OS kernel. Even if the kernel itself is

Software can be proven correct, but if you want to do anything useful with a computer system, you need more than just an OS kernel. Even if the kernel itself is "perfect", that doesn't stop vulnerabilities from appearing in the upper levels. So it's a cool accomplishment, but it's never going to be "like Mac, but totally unhackable!" or anything like that.