Live data from Hacker News

Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

nature.com

51–60 of 140 posts

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#51
post #23

"Proof assistants can’t read a maths textbook, they need continuous input from humans, and they can’t decide whether a mathematical statement is interesting or profound — only whether it is correct, Buzzard says. Still, computers might soon be able to point out consequences of the known facts that mathematicians had failed to notice, he adds." we're closer to this than people realize

Can't usefulness be approximated like Google search results of old, by connectedness to other theories.

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#52
post #32

Earlier quoted context omitted.

Why do you say this?

I'm not quite sure what you're asking about. I'm saying that we can't yet take the Wiles and Taylor-Wiles proof of Fermat's Last Theorem, feed it into a machine, and get a Lean proof of Fermat's Last Theorem.

I think the GP might have been responding to the GGP, not to your statement in the article.

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#53

Earlier quoted context omitted.

See other comment. It's sound but not decidable.

Basically it turned out that theoretical undecidability did not matter in practice, because Scholze mathematics relies so little on definitional equality. We prove theorems with `simp` not `refl`. Pierre-Marie Pédrot is quoted above as saying that various design decisions are "breaking everything around", but we don't care that our `refl` is slightly broken because it is regarded as quite a low-level tool for the tas…

Can you explain to a non-mathematician how you can prove anything without refl (which I assume is the statement “x=x is true”) ?

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#54
post #31

Does anyone know how condensed mathematics would fit into the modern theory of PDEs (which is heavily based on functional analysis)? Perhaps it's a relic of the sort of math Scholze works on, but it looks far too abstract to provide an impetus for people in those fields to embrace it. Topology, on the other hand, is relatively easy to define and work with (though there are some quirks with dual spaces of continuous l…

I think that right now it is not clear why condensed/liquid mathematics would be useful for PDEs. On the other hand, your question > Or does it "contain" topology in some sense, allowing people to continue working with notions of convergence obtained from norms? has a positive answer. You can, if you want, swap out topological spaces, and use condensed sets instead, and just continue with life as usual. At the same t…

Thanks for sharing your expertise. Would you be open to sharing your background? Obviously it's not required, but it would help contextualize what you're saying for the interested non-mathematician; otherwise we're kinda stuck with 'some guy on the Internet said ...' syndrome. :)

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#55

Earlier quoted context omitted.

I think that right now it is not clear why condensed/liquid mathematics would be useful for PDEs. On the other hand, your question > Or does it "contain" topology in some sense, allowing people to continue working with notions of convergence obtained from norms? has a positive answer. You can, if you want, swap out topological spaces, and use condensed sets instead, and just continue with life as usual. At the same t…

Thanks for sharing your expertise. Would you be open to sharing your background? Obviously it's not required, but it would help contextualize what you're saying for the interested non-mathematician; otherwise we're kinda stuck with 'some guy on the Internet said ...' syndrome. :)

Sure, I just created an account a couple of days ago, and my favourite username was already taken :oops:

I'm Johan Commelin, https://math.commelin.net/

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#56
post #45

This is going to be an exciting area. I spent some time previously playing with Coq. It's very powerful, but even proving the simplest undergraduate maths statements (say, about group theory) can prove very challenging. I believe that part of this is that Coq uses different mathematical foundations than traditional mathematics, which mostly uses set theory (ZFC, although most people don't care about the specifics). S…

You don't need subgroups, you just need injective homomorphisms.

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#57
post #23

"Proof assistants can’t read a maths textbook, they need continuous input from humans, and they can’t decide whether a mathematical statement is interesting or profound — only whether it is correct, Buzzard says. Still, computers might soon be able to point out consequences of the known facts that mathematicians had failed to notice, he adds." we're closer to this than people realize

I agree, but I think my statement is accurate today in 2021. I would love to see funds directed towards this sort of question. The big problem is that at high level so so much is skipped over, and you still sometimes have to struggle to put undergraduate-level mathematics into Lean -- this is why UG maths is such a good test case.

> The big problem is that at high level so so much is skipped over

This is an issue, but there's an established practice of writing formal sketches where the gaps in the proof are explicitly marked, and future tooling might bring ways to address these gaps once a full formal context is provided.

One issue is that Lean has little or no support for declarative proof, which is by far the most natural setting for these "proof sketches", and also brings other advantages wrt. complex proofs. (Coq has the same issue; some code was written to support declarative proofs, but it was too buggy and bitrotted, so it got removed.)

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#58

The abiltiy to automate proofs creates some interesting questions about the nature of mathematics. The article remined me of Erdos saying that you "don't need to believe in God, but you do need to believe in the book", 'the book' here being an imagined collection of mathematical proofs that are so simple, clear and beautiful that they immedieately stand out to any mathematician. I don't mind proof assistants as a way…

On the contrary proof assistants help one systematize and organize existing concepts. They are a great way to revise the basic curriculum and revolutize pedagogy. They make the creative process of defining new mathematical objects more accessible, and easier to motivate via unlocking more code reuse. They are a great way to revise the basic curriculum and revolutize pedagogy.

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#59
post #45

This is going to be an exciting area. I spent some time previously playing with Coq. It's very powerful, but even proving the simplest undergraduate maths statements (say, about group theory) can prove very challenging. I believe that part of this is that Coq uses different mathematical foundations than traditional mathematics, which mostly uses set theory (ZFC, although most people don't care about the specifics). S…

ZFC was only ever developed as a proof of concept, not as a practical foundation for formal math. Structural set theories, type theories or category-based foundations are actually a lot easier to work with, and otherwise quite equivalent in power.

Re: Mathematicians welcome computer-assisted proof in ‘grand unification’ theory

#60
post #53

Earlier quoted context omitted.

Basically it turned out that theoretical undecidability did not matter in practice, because Scholze mathematics relies so little on definitional equality. We prove theorems with `simp` not `refl`. Pierre-Marie Pédrot is quoted above as saying that various design decisions are "breaking everything around", but we don't care that our `refl` is slightly broken because it is regarded as quite a low-level tool for the tas…

Can you explain to a non-mathematician how you can prove anything without refl (which I assume is the statement “x=x is true”) ?

The jargon is a bit confusing sometimes. In Lean, "refl" does a whole lot more than prove x=x. It is of course available if you want to prove x=x, but the real power of "refl" is that it also proves x=y where x and y are definitionally equal. Or at least that's the idea; it turns out that lean's definitional equality relation is not decidable so sometimes it will fail to work even when x and y are defeq, and this is the theoretically distasteful aspect that came up on the linked Coq issue. In practice, the theoretical undecidability issue never happens, however there is a related problem where depending on what is unfolded a proof by "refl" can take seconds to minutes, and if alternative external proof-checkers don't follow exactly the same unfolding heuristics it can turn a seconds long proof into a thousand-year goose chase. By comparison, methods like "simp" have much more controllable performance because they actually produce a proof term, so they tend to be preferable.
Post reply on HN