Lean verification of AI-translated proofs may prove nothing about the original math
Navier–Stokes Lost in Translation
Autoformalisation uses AI to translate natural-language math into Lean, where proofs can be mechanically checked. But a new paper argues that faithful translation is arbitrarily hard—harder than the Halting problem—because resolving ambiguity in mathematical text sits at the top of the Solvability Complexity Index hierarchy. The authors give real examples of AI mistranslations, including OpenAI's announced Navier-Stokes blow-up proof, where the Lean proof does not match the natural-language argument.
Providing semantically faithful AI autoformalisation is harder than any computational problem including the Halting problem.
- vanyle
This paper is a large amount of nothing. First, natural language is not as precise as lean, so you have multiple ways to translate a NL argument to Lean. As shown in Fig 1, the LLM did a decent job at translating the argument about roots in a succint way.
Moreover, the paper claims that the NL arguments of Navier-Stokes are stronger than the Lean ones. My understanding is that the translator LLM got lazy and wrote the minimal amount of code that satisfied the theorem without the extra stronger claims.
It is common in mathematical papers to say "And by the way, this actually proves [stronger claim]", but this is something an AI with a precise goal of performing a translation would never do, as it's goal is to translate the proof, not to quality mathematics.
- ComplexSystems
Aside from the usual squabbling about AI, it seems the bombshell claim is this:
"In particular, we show that the formalised Lean proof does not correspond to the NL proof of blow-up of solutions to the Navier-Stokes equations."
So these authors seem to be claiming that OpenAI has not really proven Navier-Stokes at all. If I get their idea correctly, they are claiming that the LLM has not formalized the original "natural language" idea of Navier-Stokes correctly. If true, it would mean that their purported Lean proof is not actually a proof of Navier-Stokes at all, but something that is an incorrect translation of the original natural language idea. If correct, this is a really bold claim and I would like to see if other researchers agree.
- buzzy_hacker
If I'm understanding correctly, this is questioning the equivalence between the natural language proof and the lean proof, but not the correctness of the lean proof?
- stared
For a refreshment of what is Navier-Stokes in a few words: https://p.migdal.pl/equations-explained-colorfully/#navier-s...
- infogulch
The paper shows that the Lean proof and the prose (pdf) proof do not match exactly. But if the Lean theorem Lean accepted is equivalent to original problem statement published by the Clay Institute, this mismatch is of no consequence to the validity of the proof itself. That's not a trivial if: stating the problem precisely is often as hard as the proof. Validation efforts should concentrate on whether the Lean theorem is equivalent to the one published by the Clay Institute.
That said, a gap between the Lean proof and the pdf is annoying for interpretability, and interpretation is a valid aim, but that does not factor into the proof's validity.
- sigbottle
Will we ever run into a theory of meaning crisis?
_Assuming_ two failure modes:
- The lean kernel could always have a bug.
- The formalized statement may not correspond to what _mathematicians_ "actually
wanted"
It seems natural to make the argument of, "Well, even if you make the argument
that the proof can have mistakes, it's surely easier to check the problem
statement of something rather than the solution".
(A "nice property" is that, the agent doesn't need to even get "subarguments
correct" according to the _second_ criteria - maybe in the natural proof it
invents an object subtly different from the formal one, but it all checks out.
If you guarantee that the _original_ statement corresponds, then the only
possibility is the lean kernel. So it doesn't recurse infinitely, in this case).
But "definitions" are always a really weird thing that I don't think we have
good theories for? How do you quantify how much descriptive power you need to
express a question? Often times in math, the hard part is getting the definition
right - but what if the definition itself starts to become so complex and
unverifiable that no one can correspond that to anything? Well, it seems like
many interesting long-standing math problems have "relatively" simple problem
statements, in such a way that you could formalize it to lean easily, but not
sure if there's really a silver bullet w/ lean or if it's going to be turtles
all the way down.
It probably doesn't matter as long as AI keeps skyrocket […]
- dooglius
Given the high-level description of the examples, I think it's less of a "mis-translation" as it is the LLM tweaking the proof as it formalized it. Going between m+4 and m+5 is a pretty different thing than the sort of ambiguities that generally arise in parsing natural-language mathematical statements.
- Sniffnoy
Hm, looking through here, I don't see where they state what it is that OpenAI actually proved instead of Navier-Stokes blowup with forcing. I see where they do this for some other particular statements used along the way, but not for the headline result.