Splitting aspects of holomorphic distributions with locally free tangent sheaf

Abstract

In this work, we mainly deal with a two-dimensional singular holomorphic distribution $\mathcal D$ defined on $M$, where $M$ represents a complex manifold of dimension $n \geq 3$ or a germ of it, whose tangent sheaf $T_{\mathcal D}$ is locally free. As is well known, when $M=\mathbb{P}^n$ or $M=(\mathbb{C}^n,0)$, there is a one-dimensional foliation $\mathcal G$ on $M$ tangent to $\mathcal D$ and we study whether $T_{\mathcal D}$ splits starting from it. In both cases, we provide sufficient conditions on $\mathcal G$ so that there is another one-dimensional foliation $\mathcal H$ on $M$ tangent to $\mathcal D$, such that their respective tangent sheaves satisfy the splitting relation $T_{\mathcal D}=T_{\mathcal G} \oplus T_{\mathcal H}$. We introduce a concept of local division of $\mathcal D$ by $\mathcal G$, exhibiting a characterization of $\mathcal{S}(\mathcal G,\mathcal D)$, the set of points $p \in M$ where $\mathcal G$ does not locally divide $\mathcal D$ at $p$. Furthermore, for $M=\mathbb{P}^n$ we prove that the existence of such $\mathcal H$ is equivalent to $\mathcal{S}(\mathcal G,\mathcal D)=\emptyset$. Additionally, given a codimension one holomorphic foliation $\mathcal{F}$ on $\mathbb{P}^3$ with locally free tangent sheaf, we show that $T_{\mathcal F}$ splits provided there exists a nonzero holomorphic vector field on $\mathbb{P}^3$ tangent to $\mathcal{F}$. We obtain division results involving holomorphic differential forms and vector fields, and some of them could serve as alternatives to classical results coming from the De Rham-Saito Division Lemma, while others can be applied in situations not covered by the latter.