Couldn’t it very well be that you proved something that wasn't actually your program?
You can go a step farther and model the instruction set and architecture, and which point you can make proofs about the final binary directly (thereby sidestepping the problem of compiler bugs). At this point, your assumption is just that your physical hardware actually matches your model.
Correct. It can happen, where the actual code, could diverge from a lean representation of it, in a glaring or subtle way.
You can do it backwards. You declare the properties you want the resulting program/function to have, using a proof assistant like Lean, then prove that a program exists that meets those requirements, and the proof assistant spits two things: a confirmation that the proof is valid, and a piece of code that implements the proof, in the form of computer code.
At least that's how the proof assistant Coq would often be used. You still have the challenge of ensuring that you have defined the properties you really want in the first place, but at least it solves the part where you want the code to meet the specification.
The elusive 100%-coverage formal spec that covers every intended and unintended input, the interests of every stakeholder, and every possible user behavior? In the vibecoding era? No, the page has the decency to acknowledge this doesn't exist.
In the end, they settle on finding crashes with a conventional fuzzer, fixing crashes, and then... writing a formal proof that the crash is fixed? That seems... pretty pointless? Am I missing something here?
> Proving that a fuzz test has no more crashes to find is more significant than it sounds. It’s common for fuzz tests in real-world code to test for violations of meaningful high-level properties, such as encode-decode roundtripping, idempotence, algebraic laws, differential testing, self-consistency, or equivalence to reference implementations. For example, a fuzz test for the LZO compression algorithm asserts that if you compress an input, then decompress it, the result is the same as the original. If the property does not hold, the program crashes—so proving the test never crashes is equivalent to proving the property itself.
However, you're correct that this is not formal verification in the sense of a correctness proof against a full specification validated to capture what the program is intended to do. Pretty impressive though.
What they did is tried to prove that the conventional fuzzer won't find crashes. Where they found counterexamples, they fixed the bug and tried again.
In essence, a fuzzer takes random samples out of a space of possible inputs that could crash. They proved that nothing in the space of possible inputs could crash.
This is a strictly more powerful result than a fuzzer could give you.
All of human knowledge, experience, distilled down to idempotent instructions and code for specific tasks, functions, situations is fully testable against a near infinite amount of fuzz and attacks.
We do not question the strength of steel if properly treated.
Code is no different. We will enter the point where code is finally trusted as a carabiner and rope for the life of a climber.
Likely, a proliferation of experimental languages all somewhat akin to Typescript for SQL with significantly more nuanced operators to tersely capture the same outcomes as imperative languages.
They’ll compile down to be able to run performantly for game development or even for the Linux kernel (as if Linus would ever agree lol) but also they’ll be able to run on distributed execution engines with effectively a shared memory space, etc.
Allows for significantly more terse artifacts. Lower chance of hallucination, fewer output tokens, fewer thinking loop iterations and concise enough for humans to review (for domains that need it).
On top of that, additional theorem like syntax to drastically limit the ability of functions, etc. likely some sort of higher level effect system for verification. Used for many things like “constant time compilation for crypto functions”, and also “ensure acid compliance” for writes and reads in a local context, and things like “ensure only once delivery” for functions on a distributed execution engine.
At which point every program will be formally verified by default. You could think of it as AdaErlangSQL+++
How do you actually know what the LLM proved is what you want?
Now I have it working on a verifier for the bytecode transformations the optimizer uses, also using the static verification approach, to discover them all and ensure they are all valid. This one is seeming to be on track to making it fast enough to work on a real grammar as opposed to the 'academic grammars' the literature typically uses to prove the lemmas. Claude seems to be fighting this and has been working on the same refactor for over a week now so, we'll see...
jaykru•1h ago
Some mathematicians have observed a similar pattern in the recent LLM proof drops, leading them to suggest that LLMs will hit a wall in mathematical capability just beyond the convex hull of human mathematics. The sort of proofs done in formal verification are a pretty interesting litmus test for LLM reasoning since the systems considered aren't necessarily on distribution (compare with math where the "systems" and structures worked with, and proofs about them, make appearances in thousands of individual books) so the advantages in broad domain knowledge pretrained LLMs have over humans doesn't really buy you much. IMO this observation from Anthropic/Theorem lends more credibility to the convex hull hypothesis.
[0] https://www-cdn.anthropic.com/files/4zrzovbb/website/6867ead...
nextaccountic•45m ago
Yeah agents need to step up their programming game in general. They write too verbose code and are happy with duplicating code. This works up until the code is so big that they can't process the code base effectively.
If I had to guess, if you train agents to write better proofs (better modularized, etc), they will get better at programming in general. Or at very least, better at writing Haskell, since so many theorem provers are just sufficiently powerful functional programming languages. And if you get better at writing Haskell, you probably get a little better at writing Rust too. That's why I think this skill probably generalizes a lot.
So maybe training agents to do math will get them, like, use Creusot [0] or flux [1] or Aenas [2] to write proofs on their Rust code, and even when they don't, they will probably write code in ways that are more amenable for reasoning
[0] https://creusot.rs/
[1] https://flux-rs.github.io/
[2] https://lean-lang.org/use-cases/aeneas/
somethingsome•24m ago
This was to be expected, llms are trained on a very large corpus of data, they 'look' like creative from our point of view, as humans don't have that much knowledge, so, if the LLM proposes something that a human does not know, it looks like creative. But they stay neural networks after all, so very good in interpolation, very bad at extrapolation. Building new knowledge is extrapolation if it's truly outside the convex hull how the dataset.
I usually write code and ideas that are at the border of the convex hull, I haven't seen yet an llm being able to propose a really innovative solution. All the time they reuse building blocks that are already there. And I really tried pushing by making them creating proofs.
If I have an insight on some problem and I ask for the proof for it, it will usually be able to generate the proof, but that proof is never creative, and often it will use novel ideas only if I explain the novel idea. It will not come up with it alone. (And sometimes it's very hard to even explain the ideas, as it tends to return to knew waters)
Its only a data point, but I haven't seen a paper that handle this issue yet, and I don't expect them to magically become good at extrapolation due to the theory behind neural networks.