A solution to the bidimensional global asymptotic stability conjecture
Darbouxian integrability for polynomial vector fields on the 2-dimensional sphere.
Positive quadratic differential forms : linearization, finite determinacy and versal unfolding
On a Carathéodory's conjecture on umbilics : representing ovaloids
Planar vector field versions of Carathéodory's and Loewner's conjectures.
Let r = 3, 4, ... , ∞, ω. The Cr-Carathéodory's Conjecture states that every Cr convex embedding of a 2-sphere into R3 must have at least two umbilics. The Cr-Loewner's conjecture (stronger than the one of Carathéodory) states that there are no umbilics of index bigger than one. We show that these two conjectures are equivalent to others about planar vector fields. For instance, if r ≠ ω, Cr-Carathéodory's...
On nonsingular polynomial maps of ℝ²
We consider nonsingular polynomial maps F = (P,Q): ℝ² → ℝ² under the following regularity condition at infinity : There does not exist a sequence of complex singular points of F such that the imaginary parts tend to (0,0), the real parts tend to ∞ and . It is shown that F is a global diffeomorphism of ℝ² if it satisfies Condition and if, in addition, the restriction of F to every real level set is proper for values of |c| large enough.
On a conjecture of Carathéodory: Analyticity versus smoothness.
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