On closed currents invariant by holomorphic foliations, I

We consider closed positive currents invariant by a singular holomorphic foliation on an algebraic surface. We show that under some conditions the foliation must leave invariant an algebraic curve

Discrete orbits, recurrence and solvable subgroups of Diff(C^2,0)

We discuss the local dynamics of a subgroup of Diff(C^2,0) possessing locally discrete orbits as well as the structure of the recurrent set for more general groups. It is proved, in particular, that a subgroup of Diff(C^2,0) possessing locally discrete orbits must be virtually solvable. These results are of considerable interest in problems concerning integrable systems.Comment: The first version of this paper and "A note on integrability and finite orbits for subgroups of Diff(C^n,0)" are an expanded version of our paper "Discrete orbits and special subgroups of Diff(C^n,0)". An intermediate version re-submitted to the journal on March 2015 is available at http://www.fep.up.pt/docentes/hreis/publications.htm where there is also a comparison between these 3 version

Dynamics of groups of automorphisms of character varieties and Fatou/Julia decomposition for Painlev\'e 6

We study the dynamics of the group of holomorphic automorphisms of the affine cubic surfaces \begin{align*} S_{A,B,C,D} = \{(x,y,z) \in \mathbb{C}^3 \, : \, x^2 + y^2 + z^2 +xyz = Ax + By+Cz+D\}, \end{align*} where $A,B,C,$ and $D$ are complex parameters. We focus on a finite index subgroup $\Gamma_{A,B,C,D} < {\rm Aut}(S_{A,B,C,D})$ whose action not only describes the dynamics of Painlev\'e 6 differential equations but also arises naturally in the context of character varieties. We define the Julia and Fatou sets of this group action and prove that there is a dense orbit in the Julia set. In order to show that the Julia set is ``large'' we consider a second dichotomy, between locally discrete and locally non-discrete dynamics. For an open set in parameter space, $\mathcal{N} \subset \mathbb{C}^4$, we show that there simultaneously exists an open set in $S_{A,B,C,D}$ on which $\Gamma_{A,B,C,D}$ acts locally discretely and a second open set in $S_{A,B,C,D}$ on which $\Gamma_{A,B,C,D}$ acts locally non-discretely. After removing a countable union of real-algebraic hypersurfaces from $\mathcal{N}$ we show that $\Gamma_{A,B,C,D}$ simultaneously exhibits a non-empty Fatou set and also a Julia set having non-trivial interior. The open set $\mathcal{N}$ contains a natural family of parameters previously studied by Dubrovin-Mazzocco. The interplay between the Fatou/Julia dichotomy and the locally discrete/non-discrete dichotomy plays a major theme in this paper and seems bound to play an important role in further dynamical studies of holomorphic automorphism groups.Comment: We have added further details on the connections between our work and the dynamics of mapping class groups on character varieties, especially to the Bowditch BQ conditions and the related works of several authors. We have also made the writing more concise. Comments welcome

Questions about the dynamics on a natural family of affine cubic surfaces

We present several questions about the dynamics of the group of holomorphic automorphisms of the affine cubic surfaces $$S_{A,B,C,D} = \{(x,y,z) \in \mathbb{C}^3 \, : \, x^2 + y^2 + z^2 +xyz = Ax + By+Cz+D\},$$ where $A,B,C,$ and $D$ are complex parameters. This group action describes the monodromy of the famous Painlev\'e 6 Equation as well as the natural dynamics of the mapping class group on the ${\rm SL}(2,\mathbb{C})$ character varieties associated to the once punctured torus and the four times punctured sphere. The questions presented here arose while preparing our work ``Dynamics of groups of automorphisms of character varieties and Fatou/Julia decomposition for Painlev\'e~6'' \cite{RR} and during informal discussions with many people. Several of the questions were posed at the Simons Symposium on Algebraic, Complex and Arithmetic Dynamics that was held at Schloss Elmau, Germany, in August 2022 as well as the MINT Summer School ``Facets of Complex Dynamics'' that was held in Toulouse, France, in June 2023.Comment: 11 pages, comments welcome