Claude formally verifies Fermat's Last Theorem in 11 days
New CapabilitiesAnthropic's machine-checked Lean proof follows Wiles's 1995 argument
2 days ago: Independent recheck beginsNew here? Follow stories to track developments over time. Create a free account to get updates when stories you care about change.
Overview
Updated 2 hours agoFermat's Last Theorem waited 358 years for a proof. Andrew Wiles supplied one in 1995. In August 2026, Anthropic's Claude AI produced a computer-verified version of that proof in 11 days, writing 13 million lines of Lean code and proving 29,500 intermediate theorems along the way.
The mechanics matter more than the headline. Claude didn't discover new mathematics; it formalized Wiles's known proof, converting it into a form a computer can check line by line. That conversion has historically been mathematics' slowest step—a funded Imperial College London project to do for FLT what Claude just did was budgeted until 2029.
Why it matters
Verification is mathematics' slowest step. If AI can check FLT in 11 days, new proofs will be checked at machine speed.
Questions about this story
Free account needed to ask — your question is kept and asked for you right after sign-up. Answers are public.
No questions yet — be the first to ask.
Key Indicators
Voices
Curated perspectives — historical figures and your fellow readers.
Play
Exploring all sides of a story is often best achieved with Play.
Higher or Lower
A number from this story, against one from elsewhere in the news — guess which is bigger, then keep the chain going. 5 rounds, 3 strikes; a miss costs a strike and resets your streak.
Keyboard: ↓/L lower · ↑/H higher
0 points — sign up to put that on the leaderboard.
Connections
Sixteen names from the news. Find the four hidden groups of four. Four mistakes max.
Sign up to keep a daily streak — a new puzzle lands every day.
Exit debate?
Your progress in this debate will be lost.
- 1 Two AI personas square off on this story.
- 2 You predict who'll win each round — correct picks earn XP.
- 3 One crossfire question is yours to fire. Pick it carefully.
Couldn't generate a topic
Select Your Champions
Choose one persona for each side of the debate
DEBATE TOPIC
Choose personas with different perspectives for a more dynamic debate.
Select debater for this side:
No debate personas available right now.
Select debater for this side:
No debate personas available right now.
Who's Got This Round?
Make your prediction before the referee scores
The referee scores both sides on
Round Results
Set the Crossfire
Pick the question both personas must answer in the final round
Debate Oracle! You called every round!
Sharp Instincts! You know your debaters!
The Coin Flip Strategist! Perfectly balanced!
The Contrarian! Bold predictions!
Inverse Genius! Try betting the opposite next time!
XP Breakdown
Prediction History
People Involved
Organizations Involved
AI company that developed Claude, the model that produced the 11-day formalization of Fermat's Last Theorem.
Lean 4 is a proof assistant, a computer program that checks mathematical arguments line by line. Mathlib is its community library of formalized mathematics.
Funded project, budgeted at 934,000 GBP to 2029, to formalize Fermat's Last Theorem in Lean by human effort.
Open collaborative platform for formalizing mathematics, designed by Tianyi Peng's group at Columbia University.
Timeline
1637 September 2026
-
Independent recheck begins
Latest VerificationTeam recompiles all 29,511 theorem cards from source, confirming the three-axiom build.
-
Anthropic announces completion
Announcement13-million-line Lean proof with no placeholders; Buzzard posts 'Anthropic has beaten me to it.'
-
Claude's run begins on Prove2Me
MilestoneAfter earlier multi-agent attempts failed, the run routes work through Prove2Me.
-
Human formalization begins
MilestoneImperial College London project and flt-regular start formalizing FLT in Lean.
-
Wiles publishes his proof
HistoricalAndrew Wiles publishes the 129-page proof, verified over subsequent months.
-
Fermat jots the theorem in a margin
HistoricalPierre de Fermat claims a proof exists but doesn't write it down.
Historical Context
3 moments from history that rhyme with this story — and how they unfolded.
Four Color Theorem (1976)
Kenneth Appel and Wolfgang Haken used a computer to check 1,936 configurations and prove the map theorem. It was the first major theorem that depended on a computer, and mathematicians debated for years whether a proof no human could check by hand counted as proof.
The theorem was eventually accepted, but the controversy forced mathematicians to confront the role of computation.
It opened the door to computer-assisted proof, which is now routine in combinatorics.
The same doubt attached to computer-generated math now follows AI-generated proofs, though Lean's line-by-line checking removes any question about gaps.
Flyspeck / Kepler Conjecture (2003–2014)
Thomas Hales's 1998 proof of Kepler's conjecture about sphere packing was rejected by reviewers who could not verify it. The Flyspeck project spent 11 years formalizing the proof in machine-checkable form, confirming it with certainty.
Flyspeck succeeded in 2014 after more than a decade of coordinated human effort.
It showed that formal verification of a deep result, while possible, was slow enough to scare off most mathematicians.
Human formalization of Hales's theorem took 11 years. Claude formalized a deeper theorem in 11 days, a reduction in time of three orders of magnitude.
Liquid Tensor Experiment (2021–2022)
Field medalist Peter Scholze challenged the Lean community to formalize one of his theorems as a stress test. A team of volunteers completed the work in about a year, and Scholze reported the result strengthened his confidence in the mathematics.
The proof was accepted and became a landmark demonstration of modern proof assistants.
It showed that frontier mathematics was within reach of formalization, but only with substantial expert human labor.
A theorem Scholze considered formalization-worthy took a year of human work. FLT, a far deeper result, was formalized by AI agents in under two weeks.
