{"type":"post","id":"introducing-claude-fable-5-2-and-claude-mythos-6b1c41","slug":"introducing-claude-fable-5-2-and-claude-mythos-6b1c41","title":"Introducing Claude Fable 5.2 and Claude Mythos 5.2","description":"Anthropic announced Claude Fable 5.2 and Claude Mythos 5.2, with lower token prices, faster generation and stronger scores on many of its reported evaluations.","retrieval_nugget":"Anthropic announced Claude Fable 5.2 and Claude Mythos 5.2, with lower token prices, faster generation and stronger scores on many of its reported evaluations. A 1,000-agent Fable team also completed a Lean formalization of Fermat’s Last Theorem in 30 hours, illustrating how measurable proof obligations can make large agent workflows auditable.","published_at":"2026-11-09","updated_at":"2026-11-09","record_date":"2026-11-09","date_kind":"published_at","topics":["claude","anthropic"],"entities":["Anthropic","Claude Fable 5.2","Claude Mythos 5.2","Claude Opus 5.5","Lean","Fermat’s Last Theorem"],"related_patterns":["scientific-agents-need-artifact-evidence"],"novelty_label":"new_fact","what_changed":"Claude Fable 5.2 formalized Fermat’s Last Theorem in 30 hours, adding a new model and completion timeframe to AI-assisted formalization of the theorem.","prior_refs":[],"source_url":"https://www.anthropic.com/claude-fable-and-mythos-5-2","source_urls":["https://www.anthropic.com/claude-fable-and-mythos-5-2"],"schema_version":"newruntime-agent-readable-v0.2","stable_id":"post:introducing-claude-fable-5-2-and-claude-mythos-6b1c41","status":"published","visuals":[],"editor":{"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]},"routes":{"html":"https://newruntime.com/posts/introducing-claude-fable-5-2-and-claude-mythos-6b1c41/","markdown":"https://newruntime.com/posts/introducing-claude-fable-5-2-and-claude-mythos-6b1c41.md","json":"https://newruntime.com/posts/introducing-claude-fable-5-2-and-claude-mythos-6b1c41.json"},"markdown_url":"https://newruntime.com/posts/introducing-claude-fable-5-2-and-claude-mythos-6b1c41.md","next_reads":[{"type":"topic","path":"/topics/claude/","url":"https://newruntime.com/topics/claude/","title":"Claude","reason":"Explore the claude topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/claude.md","json_url":"https://newruntime.com/topics/claude.json"},{"type":"topic","path":"/topics/anthropic/","url":"https://newruntime.com/topics/anthropic/","title":"Anthropic","reason":"Explore the anthropic topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/anthropic.md","json_url":"https://newruntime.com/topics/anthropic.json"},{"type":"collection","path":"/posts/","url":"https://newruntime.com/posts/","title":"Field Notes","reason":"Open the latest editorial analysis.","media_type":"text/html","json_url":"https://newruntime.com/posts.json"},{"type":"collection","path":"/sources/","url":"https://newruntime.com/sources/","title":"Sources","reason":"See the original sources this archive cites.","media_type":"text/html"}]}