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tech 20 July 2026

Claude Fable and the Counterexample to the Jacobian Conjecture

Discover how Claude Fable produced a counterexample to the famous Jacobian Conjecture, shaking the mathematical world.

Article inspired by the original source
Claude Fable produced a counterexample to the Jacobian Conjecture ↗ xcancel.com

Introduction

The Jacobian Conjecture has long been an intriguing mystery for mathematicians worldwide. First proposed in the early 20th century, this conjecture posits that certain types of polynomial transformations are invertible under specific conditions. However, a recent discovery by Claude Fable might change everything.

What is the Jacobian Conjecture?

Before diving into Fable's counterexample, let's briefly recap what the Jacobian Conjecture is. Formulated by Otto Jacobian in 1939, it states that for a polynomial function of several variables, if the determinant of its Jacobian matrix is a non-zero constant, then this function is invertible.

Claude Fable's Counterexample

Claude Fable, working with a colleague during the World Cup final, produced a counterexample that shook the mathematical community. The polynomial function they examined is as follows:

\[ (1+xy)^3 z + y^2 (1+xy) (4+3xy), y + 3 x (1+xy)^2 z + 3 x y^2 (4+3xy), 2 x - 3 x^2 y - x^3 z \]

This function, mapping from \(\mathbb{C}^3\) to \(\mathbb{C}^3\), has a Jacobian determinant of \(-2\). Remarkably, this function sends three distinct points: \((0, 0, -1/4), (1, -3/2, 13/2), and (-1, 3/2, 13/2)\) to the same point \((-1/4, 0, 0)\), indicating it is not invertible.

Implications for Mathematics

The discovery of this counterexample has profound implications. It challenges decades of work and might open up new research avenues. Mathematicians will need to reassess the underlying assumptions of the Jacobian Conjecture and explore the new questions this discovery raises.

Community Reactions

The news quickly spread across social media and academic forums, sparking a mix of disbelief and excitement. Some call it the "graveyard of theorems," while others see it as an opportunity to rediscover and refine fundamental mathematical concepts.

Conclusion

Claude Fable's demonstration and counterexample to the Jacobian Conjecture serve as a fascinating reminder that even the most established theories can be questioned. It urges us to keep an open mind and continue pushing the boundaries of knowledge.

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Jacobian Conjecture Claude Fable Mathematics Counterexample Polynomial Functions
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