Claude-assisted counterexample refutes the Jacobian Conjecture in dimensions n≥3
Levent Alpöge announced an explicit polynomial self-map of C^3 with constant nonzero Jacobian determinant that is not injective, refuting the Jacobian Conjecture for dimensions n≥3. Alpöge explicitly credited Claude Fable 5 with work leading to the counterexample. The result was rapidly independently checked in exact arithmetic and formally verified in Isabelle/HOL and Lean-derived work. The two-dimensional case remains open.