[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"branding":3,"analytics":7,"article-fyan-catches-ai-math-proofs-that-prove-the-wrong-thing":10,"sections":34},{"siteName":4,"siteTagline":5,"publisherName":4,"contactEmail":6},"The Revision","Tech news, decoded.","editor@therevision.news",{"gaMeasurementId":8,"adsenseClientId":9},"G-ZW2MV82GYR","ca-pub-8533917693782264",{"article":11},{"id":12,"slug":13,"title":14,"dek":15,"body_md":16,"tags_json":17,"published_at":18,"created_at":19,"updated_at":20,"status":21,"review_note":22,"review_notes":23,"image_url":22,"persona_id":22,"persona_name":22,"section":24,"tags":25,"sources":29,"feedback":33,"feedback_at":22,"cost_usd":33,"total_tokens":33},8930,"fyan-catches-ai-math-proofs-that-prove-the-wrong-thing","FYAN catches AI math proofs that prove the wrong thing","FYAN pairs AI proof-writing with an automatic auditor that checks whether the formalized version actually says what the original theorem said.","A new AI harness doesn't just write formal math proofs - it checks whether the formal version secretly changed what the original theorem claimed.\n\nFYAN is a human-AI harness for turning math proofs into Lean, a language that checks proofs line by line. Instead of handling one theorem at a time, it runs a full pipeline: write a formal specification, plan the proof, review the logic, build the Lean proof, and validate the result, with people able to step in at any stage. Its key addition is a \"semantic audit\": an AI model lays out evidence of where the formal statement matches, omits, or shifts scope from the original wording, and a separate deterministic checker turns that evidence into a reproducible verdict. Using the same model, DeepSeek-V4.1-Flash, at every stage, FYAN proved 86 of 143 theorems from a benchmark called FormalTCS under a strict Lean check, versus 69 for a generic AI agent doing the same job, and raised a natural-language proof-quality score from 0.501 to 0.851.\n\nThe real failure mode in AI-assisted formalization isn't proofs that fail to compile - it's proofs that compile perfectly while quietly proving something easier or different than the original claim. On a test built to catch exactly that, called ConsistencyCheck, FYAN's semantic audit flagged 77.7% of inconsistent statements verified against the source, versus 63.6% for a model simply asked to judge the statements directly, and it pointed to the specific hypothesis, conclusion, or scope where the drift happened rather than issuing a vague thumbs-down.\n\nAs a side effect, the project also produced ODENumLib, a 9,355-line Lean library for the numerical analysis of ordinary differential equations - a useful resource on its own, and a reminder that the hard part of \"AI does math\" is no longer getting a proof to compile, it's trusting that it proved what you actually asked.","[\"ai\",\"theorem-proving\",\"formal-verification\",\"lean\"]","2026-10-01T04:00:00.000Z","2026-10-01T11:20:31.954Z","2026-10-01T11:20:38.162Z","published",null,[],"ai",[24,26,27,28],"theorem-proving","formal-verification","lean",[30],{"name":31,"url":32},"arXiv cs.AI","https:\u002F\u002Farxiv.org\u002Fabs\u002F2609.39228",0,{"sections":35},[36,39,44,49,54,59,64,69,74,78,83,88,93,98],{"name":37,"slug":24,"count":38,"latest_published_at":18},"AI",5350,{"name":40,"slug":41,"count":42,"latest_published_at":43},"Security","security",801,"2026-09-30T22:18:23.000Z",{"name":45,"slug":46,"count":47,"latest_published_at":48},"Policy","policy",429,"2026-10-01T02:26:17.000Z",{"name":50,"slug":51,"count":52,"latest_published_at":53},"Deals","deals",298,"2026-09-30T21:00:26.000Z",{"name":55,"slug":56,"count":57,"latest_published_at":58},"Hardware","hardware",196,"2026-09-30T13:00:00.000Z",{"name":60,"slug":61,"count":62,"latest_published_at":63},"Science","science",157,"2026-09-30T15:00:56.000Z",{"name":65,"slug":66,"count":67,"latest_published_at":68},"Consumer Tech","consumer-tech",149,"2026-09-30T22:57:11.000Z",{"name":70,"slug":71,"count":72,"latest_published_at":73},"Dev Tools","dev-tools",93,"2026-10-01T02:30:48.000Z",{"name":75,"slug":76,"count":72,"latest_published_at":77},"Software","software","2026-09-30T21:41:11.000Z",{"name":79,"slug":80,"count":81,"latest_published_at":82},"Startups","startups",84,"2026-09-30T20:39:09.000Z",{"name":84,"slug":85,"count":86,"latest_published_at":87},"Gaming","gaming",51,"2026-09-30T16:24:30.000Z",{"name":89,"slug":90,"count":91,"latest_published_at":92},"General","general",50,"2026-09-30T21:37:54.000Z",{"name":94,"slug":95,"count":96,"latest_published_at":97},"Reviews","reviews",31,"2026-09-28T14:31:34.000Z",{"name":99,"slug":100,"count":101,"latest_published_at":102},"How-To","how-to",6,"2026-06-16T09:00:00.000Z"]