> However, LLMs are not able to autoformalize reliably, so they got them to autoformalize each problem many times. Some of the formalizations were correct, but even the incorrect ones were useful as training data, as often they were easier problems.
So didn't actually solve autoformalization, which is why they still needed humans to translate the input IMO 2024 problems.
The reason why formalization is harder than you think is that there is no way to know if you got it right. You can use Reinforcement Learning with proofs and have a clear signal from the proof checker. We don't have a way to verify formalizations the same way.
A small detail wasn't clear to me: for these incorrectly formalized problems, how do they get the correct answer as ground truth for training? Have a human to manually solve them?
(In contrast to problems actually from "a huge database of IMO-type problems", they do have answers for these already).
Formal proofs can be mechanically checked if it's correct or not. We just don't know what's the answer. Think it as an extremely rigorous type system that typically requires really long type annotations, like annotation itself is a complex program. So if AlphaProof happens to generate a proof that passes this checker, we know that it's correct.
An incorrectly formalized problem is a different problem and a solution to any formalized problem still useful for AI training because such solutions can be mechanically checked for correctness and this does not require the hire of humans. What requires humans is the initial formalization process since that is more a language translation task which requires nuance and judgment and is difficult to mechanically verify.
While there is no perfect method, it is possible to use the agent to determine if the statement is false, has contradictory hypotheses, or a suspiciously short proof.
To you or me, sure. But I think the proof that it isn't for this AI system is that they didn't do it. Asking a modern LLM to "translate" something is a pretty solved problem, after all. That argues strongly that what was happening here is not a "translation" but something else, like a semantic distillation.
If you ask a AI (or person) to prove the halting problem, they can't. If you "translate" the question into a specific example that does halt, they can run it and find out.
I'm suspicious, basically.