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arXiv · 2610.19360

Poincaré compactifications of pullbacks of parallel vector fields under counterexamples to the real Jacobian conjecture

Francisco Braun·Paulo Machado
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Abstract

Let $F: \mathbb{R}^2 \to \mathbb{R}^2$ be a polynomial map with nowhere zero Jacobian determinant. It is known that the global invertibility of $F$ is equivalent to the pullback of a parallel vector field being parallel. In this paper, we construct the phase portraits on the Poincaré disc of the pullbacks of the canonical annular, radial, and strip vector fields under non-injective maps $F$ that have recently appeared in the literature. Our arguments use local and global properties of vector fields as well as local and global properties of functions, thereby connecting techniques from dynamical systems and singularity theory.

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Francisco Braun, Paulo Machado. 2026-10-14. Poincaré compactifications of pullbacks of parallel vector fields under counterexamples to the real Jacobian conjecture. https://arxiv.org/abs/2610.19360

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