Lean 4

Evidence (8)

• 6Hacker News·8/11/2026open_source
  Lean 4 faithfulness checker for theorem statements

  Leanscreen is an open-source faithfulness screen for Lean 4 that checks theorem statements for vacuity, misleading docstrings, and other defects the compiler accepts. It offers fast local linting as well as deeper checks with independent judges and counterexample probing, and it was benchmarked against 886 human verdicts.

• 8The New Stack·8/1/2026breakthrough
  OpenAI Claims Ten Math Proofs with Astra

  OpenAI says an internal version of its next major model, Astra, solved ten long-standing mathematical problems with less than $2,000 in token cost per problem. The work includes Lean 4 formalizations, a paper describing the proofs, and an LLM-generated reconstruction of the reasoning process. The announcement has drawn attention from mathematicians and follows earlier reports of AI systems finding cryptographic weaknesses.

• 8Hacker News·8/1/2026security
  Lean kernel soundness bug #14576 fixed

  A soundness bug in the Lean kernel was reported after an AI-assisted claim of a Collatz disproof exposed a flaw in nested inductive type handling. The Lean team shipped a fix quickly, added regression tests, and noted that independent checking still works when both the main kernel and the external checker are up to date. The issue affected only a metaprogramming path and is described as an implementation bug rather than a flaw in Lean's theory.

• 4Hacker News·7/30/2026research
  Discussion on whether Lean has become the default proof assistant

  The Hacker News discussion links to a MathOverflow post asking whether the theorem prover Lean is becoming the standard choice for formal proof work. The thread focuses on Lean's ecosystem, adoption, and whether the field is converging around a single tool. It is a community discussion rather than a product announcement or technical release.

• 7Hacker News·7/28/2026research
  Formally Verified 3D CSG Mesh Intersection in Lean 4

  This project presents what is claimed to be the first formally verified implementation of a 3D constructive solid geometry mesh intersection kernel, built in Lean 4 and checked against a short formal specification. It is also positioned as a way to rely on machine-checked proofs rather than trusting AI-generated implementation code, with a browser demo running the verified kernel in WebAssembly.

• 6Hacker News·7/26/2026research
  LLMs May Automate Proofs in Dependently Typed Languages

  The article argues that large language models, combined with proof irrelevance, could significantly reduce the manual effort required in dependently typed languages. It describes a Lean-based experiment building a Zstandard decompressor to test whether LLMs can make proof automation more practical and lessen proof engineering overhead.

• 8Hacker News·7/15/2026research
  Star Fleet Claims 20 Erdős Problem Solutions in Parallel

  Star Fleet, a Lean 4-based AI math system, claims it solved 20 Erdős problems using up to 20 parallel agent harnesses, each running a separate GPT-5.6 instance. The setup combines large-scale compute, theorem search, proof verification, and long-term dependency tracking to tackle open mathematics problems.

• 8Hacker News·7/3/2026model_release
  Leanstral 1.5 boosts Lean 4 proof engineering

  Leanstral 1.5 is a new free Apache-2.0 licensed model from Mistral AI focused on formal verification and proof engineering in Lean 4. It reports major benchmark gains, including saturating miniF2F, solving 587/672 PutnamBench problems, and setting new results on FATE-H and FATE-X, while also finding bugs in open-source codebases.