First of all, that is Fermat's Last Theorem, not Navier-Stokes.
Second of all, you did not read the link.
> In particular, we use honest when the goal is to create a valid proof. This allows for mistakes and bugs in proofs and meta-code (tactics, attributes, commands, etc.), but not for code that clearly only serves to circumvent the system (such as using the debug.skipKernelTC).
Given that AI has autonomously found proofs of `False` in Lean and other proof assistants, it is far from impossible that such a circumvention could be present somewhere in 13 million lines.
Perhaps you did not understand the Fermat theorem proof announcement/repo or the link. The 13 million lines did not use any external, possibly not honest libraries, as the proof eventually only used the fundamental axioms. So for the Fermat theorem formalization, no open open questions remain.
If we read the link, it has a section called Gold Standard: comparator and external checkers, and comparator is how OpenAI has gone about checking their lean proofs.
Second of all, you did not read the link.
> In particular, we use honest when the goal is to create a valid proof. This allows for mistakes and bugs in proofs and meta-code (tactics, attributes, commands, etc.), but not for code that clearly only serves to circumvent the system (such as using the debug.skipKernelTC).
Given that AI has autonomously found proofs of `False` in Lean and other proof assistants, it is far from impossible that such a circumvention could be present somewhere in 13 million lines.