On the density of strongly minimal algebraic vector fields
Rémi Jaoui
TL;DR
The paper proves that generic algebraic vector fields yield strongly minimal and geometrically trivial autonomous differential equations in both affine and projective settings, using a blend of model-theoretic methods (in particular the analysis of generic types in DCF$_0$) and foliation-theoretic techniques (first prolongation, canonical invariant hypersurfaces, and invariant multidistributions). Key constructions include the first projective prolongation on $\mathbb{P}(T^*X)$ and a minimality criterion based on the uniqueness of the canonical invariant horizontal hypersurface, together with singularity control to bound invariant horizontals. As a consequence, the authors exhibit dense families of strongly minimal, geometrically trivial systems, yielding the first examples of new Painlevé-type meromorphic functions of autonomous order $n\ge 4$ and providing explicit pathways to construct such functions via generic perturbations on $\mathbb{A}^n$ or $X_0=X\setminus H$. The results advance understanding of the model-theoretic structure of autonomous differential equations, demonstrate the abundance of highly irreducible dynamics in high dimensions, and open avenues for specialized specialization and foliation-driven generalizations. The work thereby integrates differential-algebraic Galois theory with geometric-analytic foliation techniques to produce robust, far-reaching classification and construction results with potential applications to Painlevé-type hierarchies and transcendental function theory.
Abstract
Two theorems witnessing the abundance of geometrically trivial strongly minimal autonomous differential equations of arbitrary order are shown. The first one states that a generic algebraic vector field of degree $d\geq 2$ on the affine space of dimension $n \geq 2$ is strongly minimal and geometrically trivial. The second one states that if $X_0$ is the complement of a smooth hyperplane section $H$ of a smooth projective variety $X$ of dimension $n$, then for $d$ large enough, the system of differential equations associated with a generic vector field on $X_0$ with a pole of order at most $d$ along $H$ is strongly minimal and geometrically trivial. This produces the first examples of meromorphic functions that are new in the sense of Painlevé and satisfy autonomous differential equations of order $n \geq 4$.
