The Gauss map of a projective foliation
Claudia R. Alcántara, Dominique Cerveau, Alcides Lins Neto
TL;DR
<p>The paper studies the Gauss map of codimension-one holomorphic foliations on complex projective space, with a focus on the threefold case $\mathbb{P}^3$ and the birationality of the Gauss map. It establishes that the maximal topological degree of the Gauss map for degree-$d$ foliations on $\mathbb{P}^3$ is $d^2$, and when achieved, the foliation admits a rational first integral of the form $F/L^{d+1}$ with $\deg F=d+1$ and $\deg L=1$. It provides birationality criteria in terms of singular data via the quantity $\sum_V \mu(\mathcal F,V)\deg V$ and plane-restriction arguments, and applies these to logarithmic and monomial foliations, including a detailed study of exceptional components such as $\mathcal E(2,3;3)$ and $\mathcal E(3,4;4)$. The work also describes methods to construct and invert Gauss maps and presents several explicit examples illustrating when birationality holds or fails, highlighting the rich structure of the moduli spaces of foliations.>
Abstract
In this paper, we study the Gauss map of a holomorphic codimension one foliation on the projective space $\mathbb{P}^n$, $n\ge 2$, mainly the case $n=3$. Among other things, we will investigate the case where the Gauss map is birational.
