Supporting the Formal Mathematics revolutionhttps://bsky.app/profile/lean-lang.orghttps://bsky.app/profile/lean-lang.org/post/3mk75jgzccs2xSVIL in Lean 2026 recordings are now available. Max Tegmark on Signal Shot: "Everybody should be able to be secure." Watch: https://www.youtube.com/watch?v=eTCW-jQrkxs&list=PLtlBXrgM1AlOg-jxchcgkLfTdwZWm-oN3 https://beneficial-ai-foundation.github.io/SVIL2026/23 Apr 2026 23:18 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mk75jgzccs2xhttps://bsky.app/profile/lean-lang.org/post/3mjwueoewuc2xThe Beneficial AI Foundation asks: "Can we prove that Signal's cryptography is secure — not just on paper, but in actual code?" Signal Shot, launched today, aims to find out. Open to contributions. 🔗 beneficialaifoundation.org/blog/signal-shot #leanlang #leanprover #softwareverification https://beneficialaifoundation.org/blog/signal-shot20 Apr 2026 16:13 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mjwueoewuc2xhttps://bsky.app/profile/lean-lang.org/post/3mijqz3qcu32q🚀 Lean 4.29.0 is out! Faster startup, simpler 𝚗𝚘𝚗𝚌𝚘𝚖𝚙𝚞𝚝𝚊𝚋𝚕𝚎 semantics, higher-order Miller pattern support in 𝚐𝚛𝚒𝚗𝚍, and a significant overhaul to reducibility and instance handling. 453 changes! 🔗 lean-lang.org/doc/reference/latest/releases/v4.29.0/ #LeanLang #LeanProver02 Apr 2026 17:43 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mijqz3qcu32qhttps://bsky.app/profile/lean-lang.org/post/3migyz4vhtc2q1/3 New Lean use case: Veil, a multi-modal verification framework for distributed protocols from George Pîrlea, Vladimir Gladshtein, Elad Kinsbruner, Qiyuan Zhao, and Ilya Sergey at NUS.01 Apr 2026 15:28 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3migyz4vhtc2qhttps://bsky.app/profile/lean-lang.org/post/3mfusnvt4k22hThe 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 #LeanProver27 Feb 2026 22:57 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mfusnvt4k22hhttps://bsky.app/profile/lean-lang.org/post/3mfscq2sdd22hThe first-ever Lean in Munich meetup happened this week! 🎥 Watch Sebastian Ullrich's full talk on Lean's foundations, software verification, and AI: youtube.com/watch?v=2Dr2149l_9Y #leanlang #leanprover #formalverification #mathematics26 Feb 2026 23:06 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mfscq2sdd22hhttps://bsky.app/profile/lean-lang.org/post/3mfkhnnfcps2zMathematician @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: https://www.youtube.com/watch?v=GHGi_XDqKNw23 Feb 2026 20:13 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mfkhnnfcps2zhttps://bsky.app/profile/lean-lang.org/post/3mfho65wgcy2oCSLib just launched — 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: 🌐 cslib.io 🤝 Contribute: https://github.com/leanprover/cslib/blob/main/CONTRIBUTING.md #LeanLang #LeanProver #CSLib #FormalVerification22 Feb 2026 17:32 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mfho65wgcy2ohttps://bsky.app/profile/lean-lang.org/post/3mfao7coe652tLean 4.28.0 is out! New symbolic simulation framework for 𝚐𝚛𝚒𝚗𝚍, user-defined 𝚐𝚛𝚒𝚗𝚍 attributes for custom tactics, a new 𝚜𝚘𝚕𝚟𝚎𝚛𝙼𝚘𝚍𝚎 in 𝚋𝚟_𝚍𝚎𝚌𝚒𝚍𝚎 for proof vs. counterexample search, and lean4checker available out of the box. https://lean-lang.org/doc/reference/latest/releases/v4.28.0/ #LeanLang #LeanProver #ProofAssistant19 Feb 2026 22:44 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mfao7coe652thttps://bsky.app/profile/lean-lang.org/post/3meoriolwq72dThe 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! ➡️ See all upcoming community events on our website: http://lean-lang.org/community/#events12 Feb 2026 19:55 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3meoriolwq72dhttps://bsky.app/profile/lean-lang.org/post/3mema6wd2c72zTerence 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." 📺 https://www.youtube.com/watch?v=SuTxpKggY30 #leanlang #leanprover11 Feb 2026 19:40 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mema6wd2c72zhttps://bsky.app/profile/lean-lang.org/post/3mejza2sntl27The 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: https://lean-lang.org/community/#events #LeanLang #LeanProver10 Feb 2026 22:30 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3mejza2sntl27https://bsky.app/profile/lean-lang.org/post/3m3xymteh422gFrom 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: https://www.youtube.com/watch?v=Ko-PzGlzYrc24 Oct 2025 23:09 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m3xymteh422ghttps://bsky.app/profile/lean-lang.org/post/3m3vbglpua22uLooking 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 https://loogle.lean-lang.org/23 Oct 2025 21:09 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m3vbglpua22uhttps://bsky.app/profile/lean-lang.org/post/3m3t2kov2c22u𝐋𝐞𝐚𝐧 𝟒.𝟐𝟒.𝟎 𝐢𝐬 𝐥𝐢𝐯𝐞! This release improves the module system, strengthens the 𝚐𝚛𝚒𝚗𝚍 tactic, and advances the standard library. Key improvements: 3.5x faster auto-completion, streamlined "try this" suggestions, new 𝚐𝚛𝚒𝚗𝚍 AC solver, enhanced 𝚖𝚟𝚌𝚐𝚎𝚗 syntax. Read more: https://lean-lang.org/doc/reference/latest/releases/v4.24.0/23 Oct 2025 00:01 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m3t2kov2c22uhttps://bsky.app/profile/lean-lang.org/post/3m3sxjn3r6s2uTactic tip: Lean's 𝚜𝚒𝚖𝚙? is an optimization tool that shows the minimal 𝚜𝚒𝚖𝚙 𝚘𝚗𝚕𝚢 call needed to close a goal. Use the 𝚜𝚒𝚖𝚙? "Try this" suggestion to insert the precise 𝚜𝚒𝚖𝚙 𝚘𝚗𝚕𝚢 call into your proof. Learn more: https://lean-lang.org/theorem_proving_in_lean4/Tactics/#using-the-simplifier #LeanLang #LeanProver #ProofAssistant22 Oct 2025 23:06 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m3sxjn3r6s2uhttps://bsky.app/profile/lean-lang.org/post/3m3ny5gpgd22s"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: https://lean-lang.org/theorem_proving_in_lean4/ #LeanLang #LeanProver #Mathematics20 Oct 2025 23:34 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m3ny5gpgd22shttps://bsky.app/profile/lean-lang.org/post/3m3dweuhllc2pReservoir 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: http://reservoir.lean-lang.org/inclusion-criteria16 Oct 2025 23:36 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m3dweuhllc2phttps://bsky.app/profile/lean-lang.org/post/3m3awlrcick2ySpeed up your #LeanLang workflow in #VSCode with shortcuts: ℹ️Ctrl/Cmd+Shift+Enter: Open the InfoView 🔡Ctrl/Cmd+Shift+O: List current file declarations, namespaces and sections 🔄Ctrl/Cmd+Shift+X: Restart the current file See more in the Lean VS Code extension manual: https://github.com/leanprover/vscode-lean4/blob/master/vscode-lean4/manual/manual.md15 Oct 2025 19:02 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m3awlrcick2yhttps://bsky.app/profile/lean-lang.org/post/3m36uiadymk2y#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. ➡ Find calendar and meeting links on our website: https://lean-lang.org/community/#events14 Oct 2025 23:19 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m36uiadymk2yhttps://bsky.app/profile/lean-lang.org/post/3m36ugwpsqc2yNew 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. ➡️Read more: https://lean-lang.org/use-cases/cedar #LeanLang #LeanProver #CedarPolicy #FormalVerification #AWS14 Oct 2025 23:18 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m36ugwpsqc2yhttps://bsky.app/profile/lean-lang.org/post/3m2u32xgpmc2z💡Did 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.org10 Oct 2025 16:17 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m2u32xgpmc2zhttps://bsky.app/profile/lean-lang.org/post/3m2rhpkbee22bThe 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: https://lean-lang.org/community/?utm_source=bluesky&utm_medium=social&utm_campaign=community#events https://lean-lang.org/community/?utm_source=twitter&utm_medium=social&utm_campaign=community#events09 Oct 2025 15:25 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m2rhpkbee22bhttps://bsky.app/profile/lean-lang.org/post/3m2k6ilnmf22wDid 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: https://github.com/leanprover/vscode-lean4/blob/master/vscode-lean4/manual/manual.md06 Oct 2025 17:52 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3m2k6ilnmf22whttps://bsky.app/profile/lean-lang.org/post/3lzm5dlc2c22nWe 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: https://youtube.com/watch?v=cKvgMjuLiuQ Pt 2: https://youtube.com/watch?v=5er4yLRd-ps Pt 3: https://youtube.com/watch?v=TJ8Tqv6A0Nc24 Sep 2025 19:11 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3lzm5dlc2c22nhttps://bsky.app/profile/lean-lang.org/post/3lzjiv7zt7c2lTwo 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. https://www.youtube.com/watch?v=q9MJWfo3DCE #AI #FormalMath #ReinforcementLearning23 Sep 2025 18:00 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3lzjiv7zt7c2lhttps://bsky.app/profile/lean-lang.org/post/3lz54shatfc26ICYMI: 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! https://leanprover-community.github.io/blog/posts/simons-lean-workshop/18 Sep 2025 19:52 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3lz54shatfc26https://bsky.app/profile/lean-lang.org/post/3lz4xucngts26Fun to see snippets of #LeanLang interspersed into this fantastic @3blue1brown.com guest video by @bensyversen.bsky.social about Euclid's Elements! [contains quote post or other embedded content]18 Sep 2025 18:23 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3lz4xucngts26https://bsky.app/profile/lean-lang.org/post/3lyxy6frtbc26🎉 Lean 4.23.0 is here! Includes many usability improvements, including: 🎯 Enhanced 'Go to Definition' supporting type class instances 🔧 Interactive error hints for faster debugging Release notes: http://lean-lang.org/doc/reference/latest/releases/v4.23.0/ #LeanLang #LeanProver #OpenSource #Mathematics #FormalVerification16 Sep 2025 18:46 +0000at://did:plc:devnu4zs2viutk26clxykpbb/app.bsky.feed.post/3lyxy6frtbc26