Anthropic mathematician Levent Alpöge disproved the 87-year-old Jacobian conjecture on July 20, 2026. Alpöge identified a counterexample to the problem using Anthropic’s Fable 5 AI model.
The announcement was published in a post on X. This development demonstrates AI's growing capacity to serve as a genuine scientific research collaborator.
The success follows a series of recent breakthroughs where AI models solved other long-standing mathematical problems.