Top all-time · #2893
Leonardo de Moura
Personal blog · leodemoura.github.io/blogprogrammingmathai
Leonardo de Moura's personal blog at leodemoura.github.io covers programming, math and ai. Since 2015, 26 different Hacker News readers have linked it 31 times, most often “Postmortem for Kernel Soundness Bug #14576”. It is still writing: the last post was on 2026-10-15, and you can follow it by feed.
Leonardo de Moura — Creator of Lean and Z3
Most-linked posts?
- Postmortem for Kernel Soundness Bug #145768 people · 9 mentions · first linked 2026-08-01
- Lean: Postmortem for the Kernel Soundness Bug Hunt6 people · 6 mentions · first linked 2026-08-24
- Signal Shot: verify the Signal protocol and its Rust implementation using Lean2 people · 2 mentions · first linked 2026-04-20
- When AI Writes the Software, Who Verifies It?2 people · 2 mentions · first linked 2026-03-22
- /about.html2 people · 2 mentions · first linked 2015-04-23
- Who Watches the Provers?2 people · 2 mentions · first linked 2026-03-17
- Why Lean?2 people · 2 mentions · first linked 2026-04-02
What Hacker News says?
How about all of these bugs from last week? https://leodemoura.github.io/blog/2026-8-24-postmortem-for-t... ...I'm not saying this FLT result is compromised. I suppose things depend on your perspective where we are on the spectrum of "finding more bugs means there are fewer left to discover" vs. "finding more bugs probably means there are still unexplored corners out there".
Comment linking /blog/2026-8-24-postmortem-for-the-kernel-soundness-bug-hunt/
on “Formalizing Fermat's Last Theorem”Submitted Lean now ships with verified kernels as a story · 204 points
HN discussionas mentioned elsewhere, there was a bug in the lean kernel exploited by AI to prove a false statement roughly a month ago https://leodemoura.github.io/blog/2026-8-1-postmortem-for-ke...
Comment linking /blog/2026-8-1-postmortem-for-kernel-soundness-bug-14576/
on “Formalizing Fermat's Last Theorem”Submitted Postmortem for Kernel Soundness Bug #14576 as a story · 9 points
HN discussionthe Nanoda type-checker for Lean is ~5,000 lines of Rust: https://leodemoura.github.io/blog/2026-3-16-who-watches-the-... ...and for those who are looking to roll-their-own: https://ammkrn.github.io/type_checking_in_lean4/title_page.h... ...and some thoughts on putting stuff in the kernel: https://lawrencecpaulson.github.io/2026/07/30/Collatz.html
Comment linking /blog/2026-3-16-who-watches-the-provers/
on “Formalizing Fermat's Last Theorem”Submitted Lean: Postmortem for the Kernel Soundness Bug Hunt as a story · 3 points
HN discussionYou still have to trust that the AI didn't exploit a bug in the Lean kernel. There was just such an instance of a bug a little over a month ago: https://leodemoura.github.io/blog/2026-8-1-postmortem-for-ke...
Comment linking /blog/2026-8-1-postmortem-for-kernel-soundness-bug-14576/
on “Formalizing Fermat's Last Theorem”Submitted Why Lean? as a story · 3 points
HN discussionThe AI labs have out considerable effort in trying to find and patch lean exploits. They explicitly set agents and have them try to prove false. > Daniel used OpenAI internal models to discover new soundness issues in the official Lean kernel and runtime https://leodemoura.github.io/blog/2026-8-24-postmortem-for-t... They found several bugs and they have patched them. Lots of work going into making sure lean is soun…
Comment linking /blog/2026-8-24-postmortem-for-the-kernel-soundness-bug-hunt/
on “Formalizing Fermat's Last Theorem”Submitted Postmortem for the Lean Kernel Soundness Bug Hunt as a story · 2 points
HN discussionHere's a recent example of an AI exploiting a soundness hole in Lean in a paper purporting to have solved the Collatz Conjecture. https://leodemoura.github.io/blog/2026-8-1-postmortem-for-ke... There's also a fairly well known incident where the Lean formalization of the Riemann Hypothesis in Mathlib was incorrect.
Comment linking /blog/2026-8-1-postmortem-for-kernel-soundness-bug-14576/
on “OpenAI withdraws three mathematical results”Submitted Signal Shot: verify the Signal protocol and its Rust implementation using Lean as a story · 2 points
HN discussionhttps://leodemoura.github.io/blog/2026-8-1-postmortem-for-ke... Do you believe no open questions remain as to the truth of the Collatz conjecture?
Comment linking /blog/2026-8-1-postmortem-for-kernel-soundness-bug-14576/
on “Navier-Stokes Announcement”Submitted The Lean Programming Language and Theorem Prover as a story · 2 points
HN discussionBut still possible [1]. [1] https://leodemoura.github.io/blog/2026-8-1-postmortem-for-ke...
Comment linking /blog/2026-8-1-postmortem-for-kernel-soundness-bug-14576/
on “The Navier–Stokes Millennium Prize Problem”Submitted When AI Writes the Software, Who Verifies It? as a story · 2 points
HN discussion> Over the year, nothing they've released with a lean proof attached has turned out false That's not true. [0] > On July 25, Ramana Kumar published a repository containing a sorry-free "disproof" of the Collatz conjecture, produced with AI assistance. It is not a valid proof because it exploits a bug in the kernel's handling of nested inductive types. Even in this dump we're talking about, it hasn't been true. [1] >…
Comment linking /blog/2026-8-24-postmortem-for-the-kernel-soundness-bug-hunt/
on “OpenAI, the Partition Principle, and Mathematics”Submitted The Lean Theorem Prover: Design, Evolution, and Impact as a story · 1 points
HN discussionIn addition to what others added below you might be interested in this postmortem https://leodemoura.github.io/blog/2026-8-24-postmortem-for-t...
Comment linking /blog/2026-8-24-postmortem-for-the-kernel-soundness-bug-hunt/
on “Fermat's Last Theorem in Lean 4”Submitted When AI Writes the Software, Who Verifies It? as a story · 1 points
HN discussionCorrection, Lean4 [1] is sponsored by Amazon, the lead developer, Leonardo de Moura is at AWS now [2]. He was previously at Microsoft Research [3]. Meeting him is a real ride, I only had the chance to talk with him once. [1] https://lean-lang.org/ [2] https://leodemoura.github.io/about.html [3] https://www.microsoft.com/en-us/research/blog/the-inner-magi...
Comment linking /about.html
on “LLMs don't do formal reasoning”Submitted Signal Shot: Verifying the Signal Protocol and Rust Implementation with Lean as a story · 1 points
HN discussionLLMs are not at the point where they can reliably complete this kind of task without making mistakes. The model checker can tell you whether the formal design specification contradicts itself, but it can't tell you whether it matches the implementation, nor whether it matches the programmers' intentions. And it's too much for humans to review by hand. This is importantly different from formal code verification, in w…
Comment linking /blog/2026-8-1-postmortem-for-kernel-soundness-bug-14576/
on “Tailscale Traces Database Corruption to 16y/o SQLite WAL-Reset Bug”Submitted Why Lean? as a story · 1 points
HN discussionYes, you still need to be careful, especially if you have reason to think that the proof was from a malicious actor. https://leodemoura.github.io/blog/2026-8-1-postmortem-for-ke... (N.B. from August 2026)
Comment linking /blog/2026-8-1-postmortem-for-kernel-soundness-bug-14576/
on “Mathematics in the Age of AI”Submitted When AI Writes the Software, Who Verifies It? as a story · 1 points
HN discussion> I encourage everyone to RTFA and not just respond to the headline. This is an example of an article which 'buries the lede'†. It should have started with the announcement of the new zlib autoformalization (!) https://leodemoura.github.io/blog/2026/02/28/when-ai-writes-... to get you excited. Then it should have talked about the rest - instead of starting with rather graceless and ugly LLM-written generic prose abo…
Comment linking /blog/2026/02/28/when-ai-writes-the-worlds-software.html
on “When AI Writes the Software, Who Verifies It?”Submitted Who Watches the Provers? as a story · 1 points
HN discussionLeonardo de Moura is also the architect of Z3 prover: https://leodemoura.github.io/about.html What a productive guy!
Comment linking /about.html
on “Theorem Proving in Lean”Submitted Proof Assistants in the Age of AI as a story · 1 points
HN discussion
