{"id":915084,"date":"2023-02-15T12:02:14","date_gmt":"2023-02-15T20:02:14","guid":{"rendered":"https:\/\/www.microsoft.com\/en-us\/research\/?post_type=msr-project&#038;p=915084"},"modified":"2023-02-15T12:02:16","modified_gmt":"2023-02-15T20:02:16","slug":"lean","status":"publish","type":"msr-project","link":"https:\/\/www.microsoft.com\/en-us\/research\/project\/lean\/","title":{"rendered":"Lean"},"content":{"rendered":"<section class=\"mb-3 moray-highlight\">\n\t<div class=\"card-img-overlay mx-lg-0\">\n\t\t<div class=\"card-background  has-background- card-background--full-bleed\">\n\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"1920\" height=\"720\" src=\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2017\/06\/math-2-banner.png\" class=\"attachment-full size-full\" alt=\"mathematical equations\" style=\"\" srcset=\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2017\/06\/math-2-banner.png 1920w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2017\/06\/math-2-banner-300x113.png 300w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2017\/06\/math-2-banner-768x288.png 768w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2017\/06\/math-2-banner-1024x384.png 1024w\" sizes=\"auto, (max-width: 1920px) 100vw, 1920px\" \/>\t\t<\/div>\n\t\t<!-- Foreground -->\n\t\t<div class=\"card-foreground d-flex mt-md-n5 my-lg-5 px-g px-lg-0\">\n\t\t\t<!-- Container -->\n\t\t\t<div class=\"container d-flex mt-md-n5 my-lg-5 \">\n\t\t\t\t<!-- Card wrapper -->\n\t\t\t\t<div class=\"w-100 w-lg-col-5\">\n\t\t\t\t\t<!-- Card -->\n\t\t\t\t\t<div class=\"card material-md-card py-5 px-md-5\">\n\t\t\t\t\t\t<div class=\"card-body \">\n\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\n\n<h1 id=\"lean\">Lean<\/h1>\n\n\n\n<p>Programming language and theorem prover<\/p>\n\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n<\/section>\n\n\n\n\n\n<h2 id=\"what-is-lean\">What is Lean?<\/h2>\n\n\n\n<figure class=\"wp-block-image alignright size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"550\" src=\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2022\/07\/LEAN-Theorem-Prover-1024x550.png\" alt=\"LEAN Theorem Prover graphic\" class=\"wp-image-865017\" srcset=\"https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2022\/07\/LEAN-Theorem-Prover-1024x550.png 1024w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2022\/07\/LEAN-Theorem-Prover-300x161.png 300w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2022\/07\/LEAN-Theorem-Prover-768x413.png 768w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2022\/07\/LEAN-Theorem-Prover-710x380.png 710w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2022\/07\/LEAN-Theorem-Prover-240x129.png 240w, https:\/\/www.microsoft.com\/en-us\/research\/wp-content\/uploads\/2022\/07\/LEAN-Theorem-Prover.png 1128w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>Lean is a functional programming language and interactive theorem prover. Our project strives to revolutionize mathematics by empowering anyone with an interest to grow in the field using Lean as their assistant. Lean was developed by Microsoft Research in 2013 as an initial effort to help mathematicians and engineers solve complex math problems. Lean is an open-source development environment for formal mathematics, also known as machine-checkable mathematics, used by and contributed to by an active community of mathematicians around the world.<\/p>\n\n\n\n<p>The digital revolution has been driven by mathematical innovation. The complexity of mathematical problems is increasing massively. Yet today\u2019s math is hard to referee, seldom read, or cited. We now have proofs that cannot be manually refereed. Collaboration in math is difficult and still limited to small groups. Historically, technical achievements through verified proofs have been gatekept by peer validation, keeping the upper most levels of the field exclusive and causing a trust bottleneck in novel explorations. Deconstructing the thought process used to achieve a result into widely checkable commentary is fertile for introductory methods. Lean is eliminating the bottleneck by digitizing mathematics and enabling computers to verify mathematical theorems. We are building the platform for the next wave of mathematicians to embrace formal mathematics.<\/p>\n\n\n\n<p>Microsoft Research collaborates with the academic and Lean community in pursuit of our mission to democratize mathematics, accelerate the frontiers of mathematical research, and improve equal access to math education. Our community of students, professors, and mathematicians&nbsp;actively contribute to Lean\u2019s mathematical library (<a class=\"msr-external-link glyph-append glyph-append-open-in-new-tab glyph-append-xsmall\" href=\"https:\/\/github.com\/leanprover-community\/mathlib4\" target=\"_blank\" rel=\"noopener noreferrer\">Mathlib<span class=\"sr-only\"> (opens in new tab)<\/span><\/a>). The community has digitized over half of the undergraduate mathematics curriculum into Lean as well as concepts at the frontiers of mathematics (such as Perfectoid Spaces) and is over one million lines of code. The community\u2019s goal is to reach 10 million lines of code in the next five years to completely digitize the undergraduate mathematics curriculum and further the progress of formalized proofs, such as Fermat\u2019s Last Theorem. Lean has already demonstrated its potential to revolutionize and radically accelerate mathematics, for example, helping Fields Medalist Peter Scholze confirm a new theorem in the <a class=\"msr-external-link glyph-append glyph-append-open-in-new-tab glyph-append-xsmall\" href=\"https:\/\/github.com\/leanprover-community\/lean-liquid\" target=\"_blank\" rel=\"noopener noreferrer\">Liquid Tensor Experiment<span class=\"sr-only\"> (opens in new tab)<\/span><\/a>. At Microsoft Research, we are working on the algorithms, data structures, and proof automation for the Lean platform to support a digital library of this scale effectively and greatly reduce formal mathematics overhead. We will claim the formal mathematics revolution is complete by reaching a de Bruijn factor of 1, when the ratio of proof length in Lean is equal to the proof length in mathematical prose. We believe Lean is spearheading the formal mathematics revolution and will empower the next generation of mathematicians to prove major open conjectures previously deemed impossible.<\/p>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-bottom is-layout-flow wp-block-column-is-layout-flow\"><\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-bottom is-layout-flow wp-block-column-is-layout-flow\"><\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-bottom is-layout-flow wp-block-column-is-layout-flow\"><\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns are-vertically-aligned-top is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-top is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<div class=\"yt-consent-placeholder\" role=\"region\" aria-label=\"Video playback requires cookie consent\" data-video-id=\"3snIzhjqsk0\" data-poster=\"https:\/\/img.youtube.com\/vi\/3snIzhjqsk0\/maxresdefault.jpg\"><iframe aria-hidden=\"true\" tabindex=\"-1\" title=\"Hoskinson Center for Formal Mathematics\" width=\"500\" height=\"281\" data-src=\"https:\/\/www.youtube-nocookie.com\/embed\/3snIzhjqsk0?feature=oembed&rel=0&enablejsapi=1\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><div class=\"yt-consent-placeholder__overlay\"><button class=\"yt-consent-placeholder__play\"><svg width=\"42\" height=\"42\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" aria-hidden=\"true\" focusable=\"false\"><g fill=\"none\" fill-rule=\"evenodd\"><circle fill=\"#000\" opacity=\".556\" cx=\"21\" cy=\"21\" r=\"21\"\/><path stroke=\"#FFF\" d=\"M27.5 22l-12 8.5v-17z\"\/><\/g><\/svg><span class=\"yt-consent-placeholder__label\">Video playback requires cookie consent<\/span><\/button><\/div><\/div>\n<\/div><figcaption class=\"wp-element-caption\">Hoskinson Center for Formal Mathematics<\/figcaption><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-top is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<div class=\"yt-consent-placeholder\" role=\"region\" aria-label=\"Video playback requires cookie consent\" data-video-id=\"SEID4XYFN7o\" data-poster=\"https:\/\/img.youtube.com\/vi\/SEID4XYFN7o\/maxresdefault.jpg\"><iframe aria-hidden=\"true\" tabindex=\"-1\" title=\"Kevin Buzzard: The rise of formalism in mathematics\" width=\"500\" height=\"281\" data-src=\"https:\/\/www.youtube-nocookie.com\/embed\/SEID4XYFN7o?feature=oembed&rel=0&enablejsapi=1\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><div class=\"yt-consent-placeholder__overlay\"><button class=\"yt-consent-placeholder__play\"><svg width=\"42\" height=\"42\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" aria-hidden=\"true\" focusable=\"false\"><g fill=\"none\" fill-rule=\"evenodd\"><circle fill=\"#000\" opacity=\".556\" cx=\"21\" cy=\"21\" r=\"21\"\/><path stroke=\"#FFF\" d=\"M27.5 22l-12 8.5v-17z\"\/><\/g><\/svg><span class=\"yt-consent-placeholder__label\">Video playback requires cookie consent<\/span><\/button><\/div><\/div>\n<\/div><figcaption class=\"wp-element-caption\">Kevin Buzzard: The rise of formalism in mathematics<\/figcaption><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-top is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-embed aligncenter is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<div class=\"yt-consent-placeholder\" role=\"region\" aria-label=\"Video playback requires cookie consent\" data-video-id=\"HL7DEkXV_60\" data-poster=\"https:\/\/img.youtube.com\/vi\/HL7DEkXV_60\/maxresdefault.jpg\"><iframe aria-hidden=\"true\" tabindex=\"-1\" title=\"2020's Biggest Breakthroughs in Math and Computer Science\" width=\"500\" height=\"281\" data-src=\"https:\/\/www.youtube-nocookie.com\/embed\/HL7DEkXV_60?feature=oembed&rel=0&enablejsapi=1\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><div class=\"yt-consent-placeholder__overlay\"><button class=\"yt-consent-placeholder__play\"><svg width=\"42\" height=\"42\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" aria-hidden=\"true\" focusable=\"false\"><g fill=\"none\" fill-rule=\"evenodd\"><circle fill=\"#000\" opacity=\".556\" cx=\"21\" cy=\"21\" r=\"21\"\/><path stroke=\"#FFF\" d=\"M27.5 22l-12 8.5v-17z\"\/><\/g><\/svg><span class=\"yt-consent-placeholder__label\">Video playback requires cookie consent<\/span><\/button><\/div><\/div>\n<\/div><figcaption class=\"wp-element-caption\">2020&#8217;s Biggest Breakthroughs in Math and Computer Science<\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-buttons is-content-justification-center is-content-justification-center is-layout-flex wp-container-core-buttons-is-layout-8057eaf3 wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button is-style-fill\"><a data-bi-type=\"button\" class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/www.microsoft.com\/en-us\/research\/video\/lightning-talks-empowering-mathematicians-with-technology\/\" target=\"_blank\" rel=\"noreferrer noopener\">Watch Research Summit talks<\/a><\/div>\n<\/div>\n\n\n\n<p>Finally, we are in collaboration with our academic partners to <a href=\"https:\/\/www.microsoft.com\/en-us\/research\/academic-program\/microsoft-research-lean-award-program\/\">develop high-quality university courses in Lean and supporting literature<\/a>, such as our upcoming textbook <a class=\"msr-external-link glyph-append glyph-append-open-in-new-tab glyph-append-xsmall\" href=\"https:\/\/leanprover.github.io\/functional_programming_in_lean\/title.html\" target=\"_blank\" rel=\"noopener noreferrer\"><em>Functional Programming in Lean,<\/em><span class=\"sr-only\"> (opens in new tab)<\/span><\/a> that will fuel the adoption of Lean as the ultimate mathematics democratizer. Our long-term goal is to make Lean available in all classrooms, providing access to formal mathematics to kids, teens, and anyone who might not think of themselves as a mathematician. Our hope is to fully democratize mathematics and to help developing students and future scientists.<\/p>\n\n\n\n<p>Formal mathematics is our primary focus, but formal methods have proven to be propitious for other applications. Lean has the potential to radically change any scope of logic that can be formalized, such as <a href=\"https:\/\/www.microsoft.com\/en-us\/research\/video\/research-talk-correct-computational-law-and-civil-procedure-with-the-lean-proof-assistant\/\">computational law and civil procedures<\/a>.<a id=\"_msocom_1\"><\/a><\/p>\n\n\n\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button is-style-outline is-style-outline--1\"><a data-bi-type=\"button\" class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/leanprover.github.io\/\" target=\"_blank\" rel=\"noreferrer noopener\">Learn more about Lean<\/a><\/div>\n\n\n\n<div class=\"wp-block-button is-style-outline is-style-outline--2\"><a data-bi-type=\"button\" class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/github.com\/leanprover\" target=\"_blank\" rel=\"noreferrer noopener\">Get the code<\/a><\/div>\n\n\n\n<div class=\"wp-block-button is-style-outline is-style-outline--3\"><a data-bi-type=\"button\" class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/leanprover.zulipchat.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">Join the conversation<\/a><\/div>\n<\/div>\n\n\n","protected":false},"excerpt":{"rendered":"<p>Lean is a functional programming language and interactive theorem prover. Our project strives to revolutionize mathematics by empowering anyone with an interest to grow in the field using Lean as their assistant. Lean was developed by Microsoft Research in 2013 as an initial effort to help mathematicians and engineers solve complex math problems. Lean is an open-source development environment for formal mathematics, also known as machine-checkable mathematics, used by and contributed to by an active community of mathematicians around the world.<\/p>\n","protected":false},"featured_media":397181,"template":"","meta":{"msr-url-field":"","msr-podcast-episode":"","msrModifiedDate":"","msrModifiedDateEnabled":false,"ep_exclude_from_search":false,"_classifai_error":"","footnotes":""},"research-area":[13556,13546,13560],"msr-locale":[268875],"msr-impact-theme":[264846],"msr-pillar":[],"class_list":["post-915084","msr-project","type-msr-project","status-publish","has-post-thumbnail","hentry","msr-research-area-artificial-intelligence","msr-research-area-computational-sciences-mathematics","msr-research-area-programming-languages-software-engineering","msr-locale-en_us","msr-archive-status-active"],"msr_project_start":"","related-publications":[871953,915948,915966,915972,915981,915996,916014,916020],"related-downloads":[],"related-videos":[888408,888393,792761],"related-groups":[901101],"related-events":[],"related-opportunities":[],"related-posts":[],"related-articles":[],"tab-content":[],"slides":[],"related-researchers":[{"type":"user_nicename","display_name":"Gabriel Ebner","user_id":42573,"people_section":"Team","alias":"gabrielebner"},{"type":"user_nicename","display_name":"Mark Encarnaci&oacute;n","user_id":32814,"people_section":"Team","alias":"markenc"},{"type":"user_nicename","display_name":"Shweti Mahajan","user_id":42594,"people_section":"Team","alias":"shmahaj"},{"type":"user_nicename","display_name":"Madan Musuvathi","user_id":32766,"people_section":"Team","alias":"madanm"},{"type":"user_nicename","display_name":"Vanessa Rodrigues","user_id":40585,"people_section":"Team","alias":"VRODRIGUESVA"},{"type":"user_nicename","display_name":"Sarah Smith","user_id":42579,"people_section":"Team","alias":"smithsarah"}],"msr_research_lab":[199565],"msr_impact_theme":["Computing foundations"],"_links":{"self":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project\/915084","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project"}],"about":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/types\/msr-project"}],"version-history":[{"count":34,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project\/915084\/revisions"}],"predecessor-version":[{"id":919740,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-project\/915084\/revisions\/919740"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/media\/397181"}],"wp:attachment":[{"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/media?parent=915084"}],"wp:term":[{"taxonomy":"msr-research-area","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/research-area?post=915084"},{"taxonomy":"msr-locale","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-locale?post=915084"},{"taxonomy":"msr-impact-theme","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-impact-theme?post=915084"},{"taxonomy":"msr-pillar","embeddable":true,"href":"https:\/\/www.microsoft.com\/en-us\/research\/wp-json\/wp\/v2\/msr-pillar?post=915084"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}