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A maths proof that is only true in Japan

bubblyworld

When the likes of Peter Scholze (fields medal!) and other very high profile mathematicians find (serious) flaws in every posted manuscript about this... I mean, it's pretty clear to me what's going on. The proof just doesn't go through.

I think the intrigue is mainly that it's at such a high level that lay mathematicians (like me) have no hope of understanding the debate. It's a situation that lends itself to crazy speculation, because nothing you say about it can easily be challenged.

aleph_minus_one

> When the likes of Peter Scholze (fields medal!) and other very high profile mathematicians find (serious) flaws in every posted manuscript about this... I mean, it's pretty clear to me what's going on. The proof just doesn't go through.

On the other hand, Ivan Fesenko (also a heavyweight; he is for example the PhD advisor of the Fields medalist Caucher Birkar) insists that Mochizuki's proof is correct.

* Here is a popular scientific article from 2016 where Ivan Fesenko presents his perspective on this topic: https://inference-review.com/article/fukugen

* A popular scientific article by David Michael Roberts (also a renowned mathematician) from 2019 about where he believes an important contentious point in the different viewpoints of Scholze/Stix vs Mochizuki lies: https://inference-review.com/article/a-crisis-of-identificat...

bubblyworld

Fantastic links, thank you. When I say Scholze and friends disagree I mean they seem to have specific mathematical criticisms with mochizuki's school that have not been addressed publically, not just "structural opinions" (for lack of a better word). For instance, see Sawin's answer here: https://mathoverflow.net/questions/467696/global-character-o...

But that's fair, it's not exactly one-sided, but to my (completely inexpert) judgement the matter seems heavily weighted against mochizuki?

netsharc

It's interesting how the debate is transferable to other topics. In theory maths should be able to be broken down to its basic components and be proven to be all true, or if something is false, then the whole thing collapses. But in practice things like this become so complex that it becomes a matter of conviction, influenced by things like ego.

Now imagine taking something like biology and vaccines. What happens if you rely on your experts and other rely on theirs, and they disagree?

bubblyworld

Yeah, it's true, there is politics in mathematical truth, for better or worse. That is slowly changing with the adoption of proof assistants, I think. A lot of well-known names (like Tao and Conrad for instance) are starting to formalise large swathes of modern maths in Lean, for instance. Perhaps it will never get to a point where it is so easy that formal proof is required to publish a result, but who knows? It seems like a start.

kamaal

>>In theory maths should be able to be broken down to its basic components and be proven to be all true, or if something is false, then the whole thing collapses.

>>But in practice things like this become so complex that it becomes a matter of conviction, influenced by things like ego.

Isn't this like doing a bunch of AND , OR operations?

How does ego become a factor here? Either an expression evaluates to true or false. There are only two outcomes, why is there a confusion here.

bubblyworld

That's true, but in practice mathematicians rarely check a proof to that level of detail. In fact, they rarely write a proof at that level of detail. There just isn't enough time to do that for every result/review, so people take shortcuts. Most of the time it's fine because trained mathematicians take good shortcuts, but sometimes things slip through.

fallingknife

The most damning part to me is that Mochizuki dismissed Joshi's work and insulted it. That's a crazy response to someone trying to improve on his theory, and shows more of a religious belief that a mathematical conclusion.

practal

I asked him more than 10 years ago if he would be interested in a formalisation of the proof, and he politely declined. I guess he was right to decline, my proposal would not have been viable then anyway.

david-gpu

Yeah, I was wondering how can debates like these exist nowadays when formal methods appear to my layman's eyes as the ultimate arbitrer of proof. Is that not how the math community looks at it?

Xmd5a

https://www.reddit.com/r/math/comments/1bmp1vk/very_salty_mo...

Lot of gems in this thread. My favorite:

>>>After Mochizuki said that Scholze-Stix were “profoundly ignorant,” I’m starting to think that this phrase is a weird form of high praise from Mochizuki.

>>I feel like the most logical strategy for Mochizuki right now is to diss. Due to the currently prevalent (and not altogether unjustified) attitude towards Mochizuki and his "cult", any praise from him will condemn what he praises to oblivion, because anyone that he praises is guilty of being part of his "fan club" simply by association. In a way, this helps to give the perception that Joshi is "independent" and still worthy of being taken seriously, though Scholze has already been dismissive of Joshi's work from the beginning.

>Wow the implications of this perspective. Theatrical and operatic. If/when Joshi’s work is vindicated, Mochizuki comes out of the shadows and says “I’m sorry son I completely raked you through the coals so that you would gain sympathy and some credibility in the eyes of the wider mathematical community, so that eventually your ideas would be recognized and hence mine as well”. I would watch the fuck out of this movie.

Xmd5a

    They've surrounded me. Cameras in every corner.
    Every move dissected in blogs, forums, peer-reviewed takedowns.
    "Cult leader". "Crank". "Outcast".
    Good. Let them watch.
    
    I'll solve equations with my right hand... and write names with my left.
    I'll take a potato chip... and eat it. [CRUNCH echoing like thunder]
    
    If I praise Joshi, he's tainted—marked as one of mine. Dismissed by association.
    But if I drag him... if I bury him in scorn... then they listen.
    Then they think, "Maybe he's different. Maybe he's not one of them.""
    I'll throw him under the bus... and save him!
    
    And the witness to my alibi... is the mathematical community itself.
    [A flicker of Scholze's blog. Stix's preprint. Joshi's strained silence.]
    They're all watching.
    
    They won't get it now.
    But when the theorems land... when every insult has aged into irony...
    
    ...they'll see it was all part of the proof.

efitz

When someone insists the only way to understand their <whatever> is to come in person and study under their direct tutelage, my scam/cult detector redlines.

moomin

I’ve read about this a lot before. My gut tells me that if you’ve got a central genius with twelve adherents and no-one else, what you’ve got is a cult, not a proof. But also, it is frankly amazing to think that Galois’ original proof was very nearly lost. It wasn’t like he’d not tried to publish. He’d been laughed out by people like Cauchy saying it was nonsense.

Xss3

Is it even true in japan if only a subset of japanese mathematicians believe it?

Theofrastus

Things have moved on since then, as artificial intelligence has started being used in formalisation, [...]

With how AI works fundamentally, wouldn't you still need to verify the results generated by AI? Doesn't seem like an applicable field for it, at least in its current state.

n4r9

I asked a very similar question a couple of weeks ago here: https://news.ycombinator.com/item?id=44028051

The top answer helped me to understand.

> Presumably an AI would formalise the proof in a system such as Lean, then you only need to trust the kernel of that proof system.

simiones

I don't think trusting the Lean kernel is enough: you also need to trust that all of the Lean code is a valid translation of the informal proof. Given that the informal proof is already gigantic, and that there is no general mechanical way to verify if a formal statement corresponds 1:1 with an informal statement, it's far from trivial to trust that the Lean representation of the proof is the same thing as the original proof.

Now, if the proof works, presumably this problem goes away: Lean can show that based on this proof, the original statement holds. But if Lean says that this formal proof doesn't work, that doesn't tell you anything about the informal proof: the error may only be in the formalization.

n4r9

Agreed; translating to Lean/Coq is more likely to prove the positive rather than the negative. It may still be useful in pinpointing where incorrect proofs go wrong.

KK7NIL

They use LLMs to help write formal proofs (in languages like Coq) that are then checked by traditional programs; they're not using AI as the checker.

https://youtu.be/e049IoFBnLA

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kitd

> Another prize is also awarded annually to people who have made important progress in studying IUT – the first such prize, with an award of $100,000, went to Mochizuki and his colleagues.

Well that's hardly suspicious at all.

8-prime

Reads like the Obama giving himself an award meme

Qision

What is so special about IUT? They say the theory is "out of this world" but in what sense exactly? Did Mochizuki found a new interesting way to look at some ideas?

enricozb

I'm not a mathematician (but I've seen exact sequences and commutative diagrams) and to me the stuff out of his IUT papers[0] looks borderline LLM-generated. I can only imagine what the LaTeX source looks like.

[0]: https://www.kurims.kyoto-u.ac.jp/~motizuki/Inter-universal%2...

IsTom

Holy moly, they weren't joking about being out of this world.

sebstefan

It reminds me of Lambda calculus

You can express `a + b` or `a * b` in their regular algebraic notation or you can express them as a lambda expressions

ADD = λab.(a S)n

MUL = λxyz.x(yz)

Manipulating these expressions instead of algebra, you can suddenly compute things such as "+ * +" (Plus times plus). That will yield you another expression for sure, but we don't even know what that means.

So maybe an analogy would be, it's like you developed a field where, from that mess, you could derive important insights and even turn them back into proofs

And there's debate on whether all invariants truly are maintained throughout the entire process

bmn__

> Plus times plus […] but we don't even know what that means

Yes, we do. https://youtu.be/RcVA8Nj6HEo?t=1017

sebstefan

The video doesn't say what you think it says

Barrin92

It's extremely complicated. The original document he wrote up was 500 pages of maths introducing effectively an entirely new theory. I studied number theory in uni, tried to read it, and understood barely anything of it.

Which obviously leads to the epistemological problem that the article points out. You had extremely good mathematicians like Scholze look at it and thought he found a flaw, then one guy from Arizona disagreeing that it is a fatal flaw and claiming to have fixed it, which Scholze doesn't agree with.

So what do you really make of it if only a handful of mathematicians can engage with it, and they can't even agree with each other. Probably the biggest value of IUT is that it puts to the test what even counts as a proof.

BobaFloutist

It kind of introduces a fun thought experiment, of a super high-level, complex equivalent of the Monty Hall Problem (which is so counterintuitive that even very intelligent and mathematically literate people will outright refuse to accept the established truth). How would we ever establish truth on something so monstrously complicated that only ~10-100 people in the world could possibly understand and at the same time so divisive that there cannot be a strong consensus?

usagisushi

Yeah, in Japan, it's well known that Pi is divisible.

https://kyoko--np-net.translate.goog/2005020901.html?_x_tr_s...

donatj

Is this the Japanese equivalent of The Onion?

madaxe_again

I thought this would be something interesting, like the Sapir whorf hypothesis applied to mathematical reasoning - but no, it’s just the old classic professor/journal editor playing silly buggers in his power-tripping dotage scenario.

bananaflag

Yeah, it's ironic how math is more or less the one "universal" truth, and we still long for somehow magically make it culturally dependent. I can definitely understand that temptation. Like the opposite one, e.g. the search for a "perfect" language (as in e.g. Umberto Eco's book). Both temptations are examples of a longing for an actual paradox or absurdity in the world.

molf

Totally get your point, but math is still a human creation. The symbols, language, and frameworks we use are cultural, and disagreement over proofs like this one shows math depends on shared understanding, not just objective truth.

bananaflag

I definitely agree with that. But that is a pale cultural dependence compared to what one would wish for.

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