๐ Lean 4.29.0 is out! Faster startup, simpler ๐๐๐๐๐๐๐๐๐๐๐๐๐ semantics, higher-order Miller pattern support in ๐๐๐๐๐, and a significant overhaul to reducibility and instance handling. 453 changes!
๐ lean-lang.org/doc/reference/latest/releases/v4.29.0/
#LeanLang #LeanProver
3/3 "As Lean's meta-programming, proof automation, and IDE infrastructure continue to mature, the case for embedding verifiers inside Lean only grows stronger."
See the use case: lean-lang.org/use-cases/veil
2/3 Veil's approach: write a model once, then apply model checking, SMT-based proofs, and interactive theorem proving from a single specification. Its embedding in Lean means a very small trusted computing base.
1/3 New Lean use case: Veil, a multi-modal verification framework for distributed protocols from George Pรฎrlea, Vladimir Gladshtein, Elad Kinsbruner, Qiyuan Zhao, and Ilya Sergey at NUS.
The Lean Y3 roadmap is building infrastructure to keep performance "visible and actionable." Radar automatically benchmarks every commit and compares it to previous ones to catch regressions and improvements.
See more: radar.lean-lang.org/about
#LeanLang #LeanProver
The first-ever Lean in Munich meetup happened this week! ๐ฅ Watch Sebastian Ullrich's full talk on Lean's foundations, software verification, and AI: youtube.com/watch?v=2Dr2149l_9Y
#leanlang #leanprover #formalverification #mathematics
Mathematician @davidbessis.bsky.social once waited 7 years for a paper to get accepted. Not because it was wrong, but because it was too complex to verify. In a recent conversation Bessis explained to @curtjaimungal.skystack.xyz how Lean could change that:
Watch: www.youtube.com/watch?v=GHGi...
CSLib just launched โ an open-source effort to formalize computer science in Lean, inspired by Mathlib. CS researchers, practitioners & enthusiasts are invited to get involved!
Learn more at:
๐ cslib.io
๐ค Contribute: github.com/leanprover/c...
#LeanLang #LeanProver #CSLib #FormalVerification
Lean 4.28.0 is out! New symbolic simulation framework for ๐๐๐๐๐, user-defined ๐๐๐๐๐ attributes for custom tactics, a new ๐๐๐๐๐๐๐ผ๐๐๐ in ๐๐_๐๐๐๐๐๐ for proof vs. counterexample search, and lean4checker available out of the box.
lean-lang.org/doc/referenc...
#LeanLang #LeanProver #ProofAssistant
The next bi-monthly #Mathlib community meeting is tomorrow Friday, 13th at 3pm UTC. Join to hear about ongoing #LeanLang formalization projects and connect with other contributors!
โก๏ธ See all upcoming community events on our website: lean-lang.org/community/#e...
Terence Tao on how math is changing, #formalverification as the enabler of scaled human-AI collaboration:
"The reason why scaling and AI and broad participation actually is a net win is because we have formal verification."
๐บ www.youtube.com/watch?v=SuTx...
#leanlang #leanprover
The next Lean FRO office hours are Feb. 11 at 4pm UTC. Bring your questions, share your projects, or just come to learn from others in the community!
See our full calendar here: lean-lang.org/community/#e...
#LeanLang #LeanProver
From The Geometry of Machine Learning at Harvard CMSA in Sept: Jared Duker Lichtman's talk explores Math, Inc. Gauss's contributions to number theory and how these results are being formalized in #LeanLang.
Watch here: www.youtube.com/watch?v=Ko-P...
Looking for a lemma in #LeanLang / #Mathlib but don't know its name? Use Loogle! to search:
By pattern: _ * (_ ^ _) finds expressions matching the pattern
By conclusion: |- tsum _ = _ * tsum _ finds specific conclusion shapes
Combine searches with commas for precision!
loogle.lean-lang.org
๐๐๐๐ง ๐.๐๐.๐ ๐ข๐ฌ ๐ฅ๐ข๐ฏ๐! This release improves the module system, strengthens the ๐๐๐๐๐ tactic, and advances the standard library.
Key improvements: 3.5x faster auto-completion, streamlined "try this" suggestions, new ๐๐๐๐๐ AC solver, enhanced ๐๐๐๐๐๐ syntax.
Read more: lean-lang.org/doc/referenc...
Tactic tip: Lean's ๐๐๐๐? is an optimization tool that shows the minimal ๐๐๐๐ ๐๐๐๐ข call needed to close a goal.
Use the ๐๐๐๐? "Try this" suggestion to insert the precise ๐๐๐๐ ๐๐๐๐ข call into your proof.
Learn more: lean-lang.org/theorem_prov...
#LeanLang #LeanProver #ProofAssistant
"Theorem Proving in Lean 4" is the essential guide for anyone using Lean for mathematical proofs. Kept up-to-date with each new Lean release, it covers everything from basic tactics to advanced proof strategies.
Read the book here: lean-lang.org/theorem_prov...
#LeanLang #LeanProver #Mathematics
Reservoir is #LeanLang's package registry, inspired by crates.io (thanks @rustfoundation.org!) Browse community-created packages and discover new tools: reservoir.lean-lang.org
Sharing is easy! GitHub repos meeting the inclusion criteria are auto-indexed: reservoir.lean-lang.org/inclusion-cr...
Speed up your #LeanLang workflow in #VSCode with shortcuts:
โน๏ธCtrl/Cmd+Shift+Enter: Open the InfoView
๐กCtrl/Cmd+Shift+O: List current file declarations, namespaces and sections
๐Ctrl/Cmd+Shift+X: Restart the current file
See more in the Lean VS Code extension manual: github.com/leanprover/v...
#LeanLang office hours are tomorrow (Wednesday the 15th) at 23:00 UTC. Bring your questions, share your projects, or just come to learn from others in the community.
โก Find calendar and meeting links on our website: lean-lang.org/community/#e...
New use case on our website: AWS's Cedar authorization policy language verified with Lean, using "verification-guided development", and integrated into Cedar's development workflow.
โก๏ธRead more: lean-lang.org/use-cases/ce...
#LeanLang #LeanProver #CedarPolicy #FormalVerification #AWS
Weโre pleased to announce #ItaLean2025: Bridging Formal Mathematics and AI, an international conference dedicated to @lean-lang.org, Formal Mathematics, and AI4Math.
๐ University of Bologna
๐ 9โ12 December 2025
Proudly supported by #Harmonic.
#LeanLang #FormalMath #AI4Math
Yes! You are absolutely correct - oversimplification on my part! ๐
No near-term plans for WASM, but it's always a possibility for much further down the road.
Check out our most recent roadmap to see what we're focusing on presently: lean-lang.org/fro/roadmap/...
๐กDid you know you can run #LeanLang in your browser without installing anything? The Lean Playground provides a full environment for experimentation, learning, and for sharing code snippets with others.
Try it out! live.lean-lang.org
The next bi-monthly #Mathlib community meeting is tomorrow (Friday Oct 10) at 2pm UTC. Join to hear about ongoing #LeanLang formalization projects and connect with contributors.
See all community events on our website:
lean-lang.org/community/?u...
Did you know the Info View in #LeanLang's #VSCode extension updates in real-time as you write proofs? Click on any part of your code to see the current proof state, goals, and hypotheses at that exact point.
Learn more about the Lean VS Code extension: github.com/leanprover/v...
FYI: The tutorials were recorded at @simonsfoundation.org Lean Workshop for Mathematics and Physical Sciences. Read more here: leanprover-community.github.io/blog/posts/s...
We really loved this series of tutorials on #metaprogramming in #LeanLang by Heather Macbeth. It's a great intro to a complex topic for novice users of #LeanProver!
Pt 1: youtube.com/watch?v=cKvg...
Pt 2: youtube.com/watch?v=5er4...
Pt 3: youtube.com/watch?v=TJ8T...
Two great talks at #HLF25 last week: Sanjeev Arora on superhuman AI mathematicians using #LeanLang, and David Silver on AI learning through experience with #LeanProver verification.
www.youtube.com/watch?v=q9MJ...
#AI #FormalMath #ReinforcementLearning
ICYMI: A great summary on the #LeanLang Community Blog of the @simonsfoundation.org 2025 MPS (Math and Phys Sciences) Workshop on #LeanProver.
The post includes links to lecture slides, videos, and a list of proposed projects and participants!
leanprover-community.github.io/blog/posts/s...