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Posted by jlebar 15 hours ago

Formalizing Fermat's Last Theorem(www.anthropic.com)
https://xenaproject.wordpress.com/2026/09/04/flt-anthropic-h...
612 points | 383 commentspage 6
mnewme 12 hours ago|
Do I miss something? But isnt there the whole code and paper of Kevin Buzzard in the training data of Claude?
sanxiyn 11 hours ago|
Yes, but Claude formalized a different proof than Buzzard is trying to, so it helps less than you think. (It certainly helps!)
dist-epoch 10 hours ago||
Lean required 300 GB of RAM, 96 cores, and took hours to compile and check the formalization.

Now they have the perfect stress test to hill-climb and optimize.

EGreg 12 hours ago||
So Fermat’s Last Theorem has been proven a long time ago? By Andrew Wiles right? Is this like Appel and Haken >>> Seymour and Robin Thomas proof of 4CT?
kzrdude 12 hours ago|
FLT was proven in 1995 by Andrew Wiles (with help of Richard Taylor).

This is not even a new proof, or at least they don't claim that it is. It's the formalization (in Lean) of an existing proof. That means, they are 'porting' the proof to a theorem proving programming language.

catigula 14 hours ago||
An AI safety company!
ReptileMan 14 hours ago||
Why didn't you ran them to find simpler proof? This could also be big.
fn-mote 13 hours ago|
That's next week's work.
ex-aws-dude 14 hours ago||
To ask a dumb question is there any chance there can be a bug in these generated proofs that makes it think its true?

Or is it the case that as long as you verify the initial statements you are trying to prove the rest doesn't matter

QuesnayJr 13 hours ago|
Lean's proofchecker is a big piece of code, so it's possible that it has a bug (and historically has had some).
stabbles 14 hours ago||
Now /simplify. Can it be half the size? Will someone at some point prove that the proof cannot be simplified further?
raverbashing 14 hours ago|
Yes. FLT follows from the fact that you can't build the equivalent representation of n-simplex turning into a hypercube in dimensions higher than 2

/s

jrflo 15 hours ago||
Holy shit, this has to be one of the most difficult proofs to formalize due to it's length and complexity right?
mswphd 12 hours ago||
not really. it's one of the most difficult ones so far for sure, but pales in comparison to something like the classification of finite simple groups.

This was initially "completed" in the 80s. You can see the timeline for cleaning up the proof in e.g. this mathoverflow answer

https://mathoverflow.net/questions/114943/where-are-the-seco...

it's something that some people have been waiting decades for, and is not yet completed.

bjourne 14 hours ago||
Yep. There may be only 25-50 people alive today in the whole world who can credibly claim to understand Wiles' proof. Now we add an LLM to that list. Absolutely mind-blowing stuff.
simpaticoder 14 hours ago|||
But isn't that understanding discarded? It is if you mean "intermediate working state" while it was generating the LEAN code. Which raises the question: I wonder what other directions it could have gone in those intermediate states? Is it possible to snapshot the state of an LLM (or a cluster of them) "in the middle of proving FLT" and then prompt it to go in a different direction with all that context?
traes 9 hours ago||||
25-50 seems like a pretty lowball estimate, I guess depending on your definition of "understand."
bigstrat2003 13 hours ago|||
> Now we add an LLM to that list.

No we cannot. LLMs do not, by their very nature, understand a single thing. You are giving far too much credence to hype and marketing.

bjourne 13 hours ago||
A meme free of charge for you, sir: https://www.reddit.com/r/singularity/comments/1jl5qfs/its_ju...
logicallee 11 hours ago|
amazing, it's a huge achievement. can someone clarify, where the writeup says "The finished proof was checked by Lean; it uses just Lean’s three standard axioms" what does this mean? Aren't there a large set of standard axioms that are also necessary? (i.e. ZFC+)? if not, since it's only three axioms, can someone say what they were?
sanxiyn 10 hours ago||
Lean's three standard axioms are documented in The Lean Language Reference.

https://lean-lang.org/doc/reference/latest/Axioms/#standard-...

The axiom of choice: axiom Classical.choice {α : Sort u} : Nonempty α → α

The axiom of propositional extensionality: axiom propext {a b : Prop} : (a ↔ b) → a = b

The quotient axiom: axiom Quot.sound : ∀ {α : Sort u} {r : α → α → Prop} {a b : α}, r a b → Eq (Quot.mk r a) (Quot.mk r b)

auggierose 3 hours ago||
I don't really know Lean, but I think this means, three axioms on top of their whole type theory machinery, to make it classical. The type theory machinery is the obfuscated encoding of the large set of standard axioms that they don't tell you about. For example, they can encode natural numbers using that machinery.
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