Mathematicians have been trying to prove the Jacobian conjecture for nearly a century, but now the Claude Fable 5 AI has apparently found a counterexample that disproves it
Mathematics
AI’s solution to 87-year-old riddle takes mathematicians by surprise
Mathematicians have been trying to prove the Jacobian conjecture for nearly a century, but now the Claude Fable 5 AI has apparently found a counterexample that disproves it
By Matthew Sparkes
20 July 2026
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Anthropic’s Fable 5 found a 216-character counterexample to the Jacobian conjecture, an 87-year-old maths problem. Experts are…
An AI called Claude Fable 5 has produced a counterexample that appears to disprove the Jacobian conjecture, open since 1939. The…
After an AI from OpenAI found a trick to solve an 80-year-old conjecture from Paul Erdős, mathematicians have borrowed the same…
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Claude Fabel 5 disproved the Jacobian conjecture over the weekend, landing days after the capabilities of China's Kimi AI became…
Claude Fable 5 Cracks an 87-Year Maths Problem - And You Can Check its Work
