Reconstructing orbit closures from their boundaries

Reconstructing a minimal topological dynamical system from a set of return times

We investigate to what extent a minimal topological dynamical system is uniquely determined by a set of return times to some open set. We show that in many situations this is indeed the case as long as the closure of this open set has no non-trivial translational symmetries. For instance, we show that under this assumption two Kronecker systems with the same set of return times must be isomorphic. More generally, we show that if a minimal dynamical system has a set of return times that coincides with a set of return times to some open set in a Kronecker system with translationarily asymmetric …

On geometrically finite degenerations I: boundaries of main hyperbolic components

In this paper, we develop a theory on the degenerations of Blaschke products $\mathcal{B}_d$ to study the boundaries of hyperbolic components. We give a combinatorial classification of geometrically finite polynomials on the boundary of the main hyperbolic component $\mathcal{H}_d$ containing $z^d$. We show the closure $\overline{\mathcal{H}_d}$ is not a topological manifold with boundary for $d\geq 4$ by constructing self-bumps on its boundary.

拟态射空间上的动力学及其在近似格理论中的应用

Dynamics on spaces of quasimorphisms and applications to approximate lattice theory

本文研究可数群在拟态射空间上的动力学，证明上同调非平凡拟态射无不变测度并分类平稳测度，进而应用于均匀近似格包络，扩展了相关结果。

Backward orbits and petals of semigroups of holomorphic self-maps of the unit disc

We study the backward invariant set of one-parameter semigroups of holomorphic self-maps of the unit disc. Such a set is foliated in maximal invariant curves and its open connected components are petals, which are, in fact, images of Poggi-Corradini's type pre-models. Hyperbolic petals are in one-to-one correspondence with repelling fixed points, while only parabolic semigroups can have parabolic petals. Petals have locally connected boundaries and, except a very particular case, they are indeed Jordan domains. The boundary of a petal contains the Denjoy-Wolff point and, except such a fixed po…