@__alpoge__: hello there the jacobian conjecture is false thanx...
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@__alpoge__: hello there the jacobian conjecture is false thanx...

@__alpoge__
2026.07.21
·X (Twitter)·by JunhaRyu
#Algebraic Geometry#Jacobian Conjecture#Mathematics

Key Points

  • 1This post claims to provide a counterexample that disproves the long-standing Jacobian conjecture in three dimensions.
  • 2The author presents a specific polynomial map from $\mathbb{C}^3$ to $\mathbb{C}^3$ that possesses a constant Jacobian determinant of negative two.
  • 3The provided map is shown to be non-invertible by identifying multiple distinct coordinate points that map to the same target output.

The paper presents a counterexample to the Jacobian Conjecture, a long-standing problem in algebraic geometry which posits that any polynomial map F:Cn→CnF: \mathbb{C}^n \to \mathbb{C}^n with a non-zero constant Jacobian determinant must have a polynomial inverse. The author provides an explicit polynomial map F:C3→C3F: \mathbb{C}^3 \to \mathbb{C}^3 defined by the mapping:

F(x,y,z)=((1+xy)3z+y2(1+xy)(4+3xy),  y+3x(1+xy)2z+3xy2(4+3xy),  2x−3x2y−x3z)F(x, y, z) = \left( (1+xy)^3 z + y^2 (1+xy) (4+3xy), \,\, y + 3 x (1+xy)^2 z + 3 x y^2 (4+3xy), \,\, 2 x - 3 x^2 y - x^3 z \right)

The core methodology involves constructing a map where the Jacobian determinant, det⁡(JF)\det(JF), is calculated to be the constant value −2-2. Since the Jacobian determinant is a non-zero constant, the map satisfies the initial condition required by the conjecture.

To demonstrate that the map does not possess a polynomial inverse, the author identifies specific points in the domain that map to a single target point in the codomain. Specifically, the points (0,0,−1/4)(0, 0, -1/4), (1,−3/2,13/2)(1, -3/2, 13/2), and (−1,3/2,13/2)(-1, 3/2, 13/2) are all mapped by FF to the image point (−1/4,0,0)(-1/4, 0, 0). The existence of these distinct pre-images for a single point demonstrates that the map is not injective. Because a polynomial map with a polynomial inverse must be an automorphism and therefore injective, the failure of injectivity in this mapping provides a constructive disproof of the Jacobian Conjecture. The author credits Akhil and Fable for their contributions to the derivation and verification of this counterexample.