# Claude Fable 5 surfaces a three-variable counterexample that topples the 87-year-old Jacobian conjecture

One of algebraic geometry's most obstinate open problems was undone by something that fits in a single post on X. No 200-page manuscript. No cluster grinding away for months on a distributed computation. Just a compact formula in three dimensions whose Jacobian determinant equals -2. Levent Alpöge,

| Fact | Value |
| --- | --- |
| Published | 6 August 2026 |

Source: https://egamers.io/claude-fable-5-surfaces-a-three-variable-counterexample-that-topples-the-87-year-old-jacobian-conjecture/